Automatic Patents (Class 331/183)
  • Patent number: 6657503
    Abstract: A ring oscillator circuit, such as a VCO, with a relatively high level of noise rejection for noise originating from both the voltage supply and ground. The ring oscillator circuit is composed of a plurality of differential delay circuits, each differential delay circuit generating a differential output signal that is a delayed (and preferably inverted) version of a differential input signal. Each differential delay circuit includes first and second input transistors for receiving the differential input signal. Each differential delay circuit also includes first and second load transistors coupled in parallel with the respective first and second input transistors. Each differential delay circuit further includes a first current source coupled between the first input transistor and a first power supply terminal (e.g.
    Type: Grant
    Filed: April 25, 2002
    Date of Patent: December 2, 2003
    Assignee: Broadcom Corporation
    Inventor: Bin Liu
  • Patent number: 6657507
    Abstract: An oscillator circuit including an integrated circuit amplifier, an integrated circuit active resistance circuit to set the gain of the amplifier, a crystal resonator to set the frequency of the signal generated by the oscillator circuit, and a pair of capacitors respectively situated at the inputs and outputs of the amplifier to assist in the starting of the oscillation signal. The active resistance circuit is responsive to an input signal in order to set the gain of the amplifier slightly above unity gain in order to meet the criterion for oscillation, but not too much above unity gain where the oscillator would unduly consume too much power. Thus, the oscillator has inherent low power characteristics. The active resistance circuit allows the amplifier gain to be set by software or other electronic means.
    Type: Grant
    Filed: January 2, 2002
    Date of Patent: December 2, 2003
    Assignee: Intel Corporation
    Inventors: Robert R. Fulton, Chinnugounder Senthilkumar, Tea Lee
  • Patent number: 6653908
    Abstract: An oscillator with oscillator and voltage control circuitry for generating an oscillation signal having an amplitude that is automatically controlled for a selectively minimized phase noise. Automatic level control is used for controlling the amplitude of the oscillation signal such that the phase noise of the oscillation signal can be maintained at some selected level, e.g., minimized. The minimum signal voltage appearing across the oscillation circuit is monitored for controlling the bias of the circuit to prevent it from entering a saturation state, thereby avoiding adverse loading effects responsible for degraded phase noise performance.
    Type: Grant
    Filed: October 18, 2001
    Date of Patent: November 25, 2003
    Assignee: National Semiconductor Corporation
    Inventor: Mark Alan Jones
  • Patent number: 6650196
    Abstract: A variable frequency output signal is generated in response to a control signal by providing an oscillator (50) that generates the output signal in different frequency ranges depending on the value of an operating parameter, such as DC bias current. A first circuit (60) adjusts the operating parameter values and a second circuit (80) controls the Kvco of the oscillator.
    Type: Grant
    Filed: September 28, 2001
    Date of Patent: November 18, 2003
    Assignee: Broadcom Corporation
    Inventor: Andrew D. Nguyen
  • Patent number: 6642796
    Abstract: A digital phase-quadrature oscillator generates a series of sine values representative of a sine wave, and a series of cosine values representative of a cosine wave. In each iteration of the oscillator, a sum of the squares of past sine and cosine values is used as a negative feedback term in synthesizing next sine and cosine values, in order to stabilize the amplitudes of the sine and cosine values.
    Type: Grant
    Filed: February 15, 2002
    Date of Patent: November 4, 2003
    Assignee: Radiodetection Limited
    Inventor: John M. Royle
  • Publication number: 20030184368
    Abstract: A digital FM demodulator employs a baseband phase lock loop (BBPLL), which is particularly effective for long range reception, for combining and demodulating a pair of signals represented by the mathematical expression A(t)ej&thgr;(t) to result in an approximation of d&thgr;/dt. This approximation is then subjected to an inverse of the linear approximation of the frequency response of the BBPLL that produces a very accurate &thgr;. This is conveniently achieved with a IIR filter whose transfer function happens to be the same as the inverse of the linear approximation of the frequency response of the BBPLL. The derivative is then taken of &thgr; to produce a very accurate d&thgr;/dt, the desired result for the output of an FM demodulator. To aid operation of the BBPLL, the incoming digital intermediate frequency is upsampled by a combination of sample and hold and FIR filtering prior to being processed by the BBPLL.
    Type: Application
    Filed: April 2, 2002
    Publication date: October 2, 2003
    Inventors: Junsong Li, Jon D. Hendrix, Raghu G. Raj
  • Patent number: 6577204
    Abstract: In an electronic circuit supplied from supply terminals, a terminal in the circuit being biased to a voltage between the supply terminal voltages, connections from power supply terminals are made via current generator means. The circuit is preferably an RF, balanced and/or oscillator circuit. The current generator means are preferably controllable current generators, preferably controlled by an AGC, or a common mode or differential voltage control circuit. Preferably, the controllable current generators comprise a FET or are substantially constituted by each one MOS-FET. A balanced, common-base, low-voltage Pierce crystal oscillator with two transistors and four to six current generator means is disclosed.
    Type: Grant
    Filed: December 12, 2001
    Date of Patent: June 10, 2003
    Assignee: Nokia Corporation
    Inventor: Jacob Midtgaard
  • Publication number: 20030090334
    Abstract: A circuit and method for assuring rapid initiation of resonant oscillation of an electromechanically oscillatory system driven by phase lock loop circuits. An open loop starting signal commences driving of the object at a starting frequency above the resonant frequency. The starting signal reduces the drive frequency until the resonant frequency of the system is reached and the starting signal is removed.
    Type: Application
    Filed: December 22, 2000
    Publication date: May 15, 2003
    Applicant: Honeywell International Inc.
    Inventor: William A. Harris
  • Patent number: 6504436
    Abstract: A tuning circuit includes an oscillator that receives an oscillating input signal and a control signal, and generates an oscillating output signal. The control signal is obtained from a frequency control circuit that compares the phases of the oscillating output signal and a reference signal. The control signal controls the transconductance of a transconductance element in the oscillator, thereby controlling the oscillator output frequency. The oscillating input signal is obtained from an amplitude control circuit that detects an amplitude limit of the oscillator output. The oscillator output amplitude is responsive to the oscillating input signal. Frequency control and amplitude control in this tuning circuit are mutually independent, so their respective control loops remain stable under all frequency and amplitude combinations.
    Type: Grant
    Filed: May 23, 2001
    Date of Patent: January 7, 2003
    Assignee: Oki Electric Industry Co., Ltd.
    Inventors: Akira Horikawa, Akira Yoshida, Takashi Taya
  • Patent number: 6483391
    Abstract: Systems for controlling the amplitude of the output signal of a controllable oscillator in a frequency synthesizer are provided. One such system provides a circuit having a controllable oscillator and an amplitude control circuit. The controllable oscillator is configured to generate an output signal having a predefined frequency and a predefined amplitude. The controllable oscillator is also configured with a plurality of operational states that are controlled by the amplitude control circuit. Each operational state of the controllable oscillator defines a particular current bias associated with a distinct amplitude of the output signal of the controllable oscillator. The amplitude control circuit receives the output signal of the controllable oscillator and determines the amplitude. When the amplitude of the output signal of the controllable oscillator is less than the predefined amplitude, the amplitude control circuit provides a control signal to the controllable oscillator.
    Type: Grant
    Filed: March 30, 2001
    Date of Patent: November 19, 2002
    Assignee: Conexant Systems, Inc.
    Inventors: Rahul Magoon, Alyosha C. Molnar, Jeff Zachan
  • Patent number: 6469587
    Abstract: A differential voltage-controlled oscillator (VCO) employs a pair of accumulation-mode varactors driven with a differential control voltage to generate a differential oscillating waveform. The differential control voltage is formed from a pair of level-shifted input differential control voltage components. Level shifting of the input control voltages and driving the varactors with a differential control voltage allows for biasing of the varactors over a substantial range of capacitance variation. Such differential VCO may be employed within a phase-locked loop (PLL) circuit, with the pair of input control voltages being provided by the loop filter of the PLL circuit. The differential VCO comprises a differential control voltage to voltage converter (CV2VC) coupled to an LC-tank VCO. To improve common-mode noise rejection of the LC-VCO, the inductors of the LC-tank may be AC-coupled to the supply voltage, and the output differential oscillating waveform may be AC-coupled to the LC-tank through capacitors.
    Type: Grant
    Filed: December 4, 2000
    Date of Patent: October 22, 2002
    Assignee: Agere Systems Guardian Corp.
    Inventor: John E. Scoggins
  • Patent number: 6469586
    Abstract: Recent trends have seen the desire for lower and lower supply voltages in radio frequency (RF) components as this leads to lower power consumption and, therefore, longer battery life. As well, lower voltages and less current means that mobile products can be made to require fewer battery cells leading to lighter, more compact devices. The present invention discloses a novel topology for providing a low-voltage voltage-controlled oscillator (VCO). The novel topology is based on the negative transconductance oscillator. However, the novel topology of the invention eliminates transistor ‘stacking’ in the oscillator circuit, thereby allowing the oscillator circuit to be operated at a supply voltage only slightly higher than the turn-on voltage for a single transistor.
    Type: Grant
    Filed: August 25, 2000
    Date of Patent: October 22, 2002
    Assignee: SiGe Semiconductor Inc.
    Inventors: John William Mitchell Rogers, Calvin Plett
  • Patent number: 6340920
    Abstract: An oscillator is provided with an inverter, a quartz crystal, a voltage source, an upper clamper, a ground node, a lower clamper, and a feedback-controlled switch. The inverter is connected in parallel to the quartz crystal having a crystal input and a crystal output. The upper damper is connected between the inverter and the voltage source. The lower damper is connected between the inverter and the ground node. The feedback-controlled switch has a pair of switch control nodes connected to the crystal input, a switch input connected to the crystal output, and a switch output connected to the upper damper and the lower clamper. The potential at the switch output is determined by voltage levels at the switch control nodes and the switch input in order to control the upper damper and the lower damper while oscillating.
    Type: Grant
    Filed: April 12, 2000
    Date of Patent: January 22, 2002
    Assignee: Industrial Technology Research
    Inventor: Yuh-Kuang Tseng
  • Patent number: 6329884
    Abstract: There is disclosed an oscillator circuit in which the first capacitor is connected between the input side of a CMOS inverter in a quartz oscillator circuit and a higher potential side, the second load capacitor is connected between the input side of the inverter and a lower potential side, the third load capacitor is connected between the output side of the inverter and the higher potential side, and the fourth load capacitor is connected between the output side of the inveter and the lower potential side, so that variation in amplitudes of the voltage sources synchronized with the oscillation can be reduced with the realization of lower current consumption.
    Type: Grant
    Filed: October 8, 1998
    Date of Patent: December 11, 2001
    Assignee: Nippon Precision Circuits, Inc.
    Inventors: Kunihiko Tsukagoshi, Satoru Miyabe, Kazuhisa Oyama
  • Patent number: 6323738
    Abstract: A voltage-controlled oscillator comprises a level converting circuit, an amplitude controller, a voltage-controlled oscillation section having differential delay cells connected in a ring form, and an output level converting circuit. The level converting circuit has limiters which respectively limit a maximum value and a minimum value of a control current. Those limiters permit only a region where the voltage-controlled oscillation section properly performs its oscillating operation to be used.
    Type: Grant
    Filed: June 28, 2000
    Date of Patent: November 27, 2001
    Assignee: Kabushiki Kaisha Toshiba
    Inventors: Akihiko Yoshizawa, Shuichi Takada
  • Patent number: 6278337
    Abstract: An integrated oscillator and associated methods are provided for providing clock signals. The integrated oscillator preferably includes a micro-mechanical oscillating circuit for providing an oscillating clock signal. The micro-mechanical oscillating circuit preferably includes a support layer, a fixed layer positioned on a support layer, remaining portions of a sacrificial layer positioned only on portions of the fixed layer, and an oscillating layer positioned on the remaining portions of the sacrificial layer, overlying the fixed layer in spaced relation therefrom, and extending lengthwise generally transverse to a predetermined direction for defining a released beam for oscillating at a predetermined frequency. The spaced relation is preferably formed by removal of unwanted portions of the sacrificial layer.
    Type: Grant
    Filed: October 5, 1999
    Date of Patent: August 21, 2001
    Assignee: STMicroelectronics, Inc.
    Inventors: Tsiu Chiu Chan, Melvin Joseph DeSilva, Syama Sundar Sunkara
  • Patent number: 6278338
    Abstract: A crystal oscillator apparatus is described that has a wide dynamic frequency range and that is capable of supporting a broad range of crystal types. The present invention reduces the unwanted side effects that are associated with the prior art crystal oscillator designs, such as the clipping of signals, the introduction of signal distortion and unwanted signal harmonics. The present invention reduces the total wasted loop gain of the oscillator while also reducing the amount of integrated circuit real estate required to implement the crystal oscillator. The crystal oscillator apparatus of the present invention preferably comprises a crystal resonator circuit, an inverting amplifier, a bias circuit, a reference circuit, and a peak detector circuit. The present invention takes advantage of Automatic Gain Control (AGC) design techniques. The gain of the present crystal oscillator is automatically regulated using a closed loop circuit design.
    Type: Grant
    Filed: May 1, 2000
    Date of Patent: August 21, 2001
    Assignee: Silicon Wave Inc.
    Inventor: Lars Gustaf Jansson
  • Patent number: 6271734
    Abstract: A piezoelectric oscillator which is excellent in noise characteristic and aging characteristic is implemented by a piezoelectric oscillator comprising: a Colpitts oscillator including a piezoelectric resonator and an oscillation transistor; amplification means for amplifying an output of the Colpitts oscillator; and rectification means for rectifying an output of the amplification means, an output of the rectification means being fed back to base of the oscillation transistor to keep an oscillation output level constant, in which a base bias is set so as to provide the oscillation transistor with an operation point located in the vicinity of a saturation region, and in which a feedback current from the rectification means is supplied to the base of the oscillation resistor so as to make the operation point approach to the saturation region when the saturation output level has become high and so as to make the operation point go away from the saturation region when the oscillation output level has become low.
    Type: Grant
    Filed: February 17, 2000
    Date of Patent: August 7, 2001
    Assignee: Toyo Communication Equipment Co., Ltd.
    Inventor: Tomio Satoh
  • Patent number: 6271737
    Abstract: A communications device, such as a one-way pager, comprises a receiver having a frequency down-conversion means for frequency converting an input signal using a local oscillator signal generated by a signal generating means, which may comprise a frequency synthesizer. The signal generating means (20) comprises a voltage controlled oscillator (VCO) (50) including an oscillator transistor (68) coupled to dc voltage source (54), frequency determining reactive elements coupled to the oscillator transistor (68) for determining the frequency to be generated, at least one of the reactive elements (80) being adjustable in response to an applied voltage and means (82,84) for phase modulating the oscillator transistor (68) in an opposite sense to that caused by voltage perturbations due to noise in the dc voltage supplied by the dc voltage source (54).
    Type: Grant
    Filed: March 31, 1999
    Date of Patent: August 7, 2001
    Assignee: U.S. Philips Corporation
    Inventor: Stephen W. Watkinson
  • Patent number: 6268777
    Abstract: The voltage controlled oscillator (VCO) of the present invention generally includes a energy storage circuit portion, an oscillator operably connected to the energy storage circuit portion, a varactor connected to the oscillator and energy storage circuit portion, and an amplitude controller that is operably connected to the energy storage circuit portion, oscillator, and varactor. The energy storage circuit portion includes an inductance and a capacitance. The oscillator provides an oscillating output signal having a frequency and an amplitude. The varactor has a capacitance and receives an input signal having a varying level. The capacitance of the varactor varies according to the level of the input signal. The amplitude controller sets the amplitude of the oscillating output signal. Meanwhile, the inductance of the energy storage circuit portion, the capacitance of the energy storage circuit portion, and the varying capacitance of the varactor are used to set the frequency of the oscillating output signal.
    Type: Grant
    Filed: November 20, 1998
    Date of Patent: July 31, 2001
    Assignee: Applied Micro Circuits Corporation
    Inventor: James R. Welch
  • Patent number: 6194973
    Abstract: An oscillator having an adjustable gain circuit provides abundant gain when the oscillator is first powered up but reduces the gain substantially below its start-up value once oscillations build up, thereby substantially reducing the power consumed. The oscillator comprises an inverting amplifier coupled to a resonator, an oscillation detector coupled to the inverting amplifier amplifier, and a common-gate amplifier coupled to the oscillation detector. The inverting amplifier amplifies oscillations of the resonator according to a gain. The oscillation detector outputs a detection signal in response to oscillations of the resonator. The level of the detection signal is proportional to the amplitude of the oscillations. The common-gate amplifier receives the detection signal and, in response, limits the current to the inverting amplifier to control the gain based on the level of the detection signal.
    Type: Grant
    Filed: May 29, 1998
    Date of Patent: February 27, 2001
    Assignee: Intel Corporation
    Inventor: Thomas A. Williamson
  • Patent number: 6172575
    Abstract: An oscillation circuit includes an oscillation terminal, and an inverter which is coupled to the oscillation terminal and which outputs an oscillation signal according to a resonant frequency of a resonator to be connected to the oscillation terminal. The oscillation circuit also includes resistors having different resistance values, and a select circuit which sequentially operatively connects the resistors between the inverter and a voltage source in response to the oscillation signal.
    Type: Grant
    Filed: April 1, 1999
    Date of Patent: January 9, 2001
    Assignee: Oki Electric Industry Co., Ltd.
    Inventor: Nobuaki Shinmori
  • Patent number: 6166609
    Abstract: A crystal oscillation circuit that is capable of operating stably with a low power consumption includes a signal inversion amplifier and a power control circuit that controls the power voltage of this signal inversion amplifier in accordance with an oscillation output. The power control circuit includes a power voltage generation circuit that outputs a plurality of power voltages of different values; a determination control portion that determines the optimal value of the power voltage to be applied to the signal inversion amplifier, based on the oscillation output; and a multiplexer that controls the switching of the power voltage applied to the signal inversion amplifier from the power voltage generation circuit, based on the result of that determination.
    Type: Grant
    Filed: April 8, 1998
    Date of Patent: December 26, 2000
    Assignee: Seiko Epson Corporation
    Inventors: Shinji Nakamiya, Tadao Kadowaki, Yoshiki Makiuchi
  • Patent number: 6137375
    Abstract: A circuit for controlling the loss of a VCO in a master-slave tuning system includes an envelope detector, an amplitude regulator, a current-mode circuit, and a low-pass filter. The envelope detector receives the VCO output voltage and provides VCO output envelope voltage, V.sub.ENV. The amplitude regulator receives V.sub.ENV and a reference voltage, V.sub.REF, and provides a sourcing current if V.sub.ENV is less than V.sub.REF, and draws a sinking current if V.sub.ENV is greater than V.sub.REF. The current-mode circuit receives V.sub.ENV and provides a control current, I.sub.Q. The low-pass filter has high DC gain for integrating the control current and the sourcing or sinking current to provide the VCO control voltage, V.sub.CON, to the VCO. The control current, I.sub.Q, is proportional to the inverse of V.sub.ENV multiplied by the time derivative of V.sub.ENV.
    Type: Grant
    Filed: May 28, 1999
    Date of Patent: October 24, 2000
    Assignee: The Trustees of Columbia University in the City of New York
    Inventor: Dandan Li
  • Patent number: 6133801
    Abstract: A crystal oscillation circuit includes a main oscillation circuit, an auxiliary oscillation circuit, and a control circuit. The main oscillation circuit has a crystal resonator. The auxiliary oscillation circuit increases an exciting current of the crystal resonator to assist the start of oscillation of the main oscillation circuit. The control circuit connects the auxiliary oscillation circuit parallel to the main oscillation circuit at the start of oscillation to increase an exciting current of the crystal resonator.
    Type: Grant
    Filed: April 23, 1997
    Date of Patent: October 17, 2000
    Assignee: NEC Corporation
    Inventor: Shoichi Tanaka
  • Patent number: 6124765
    Abstract: An integrated oscillator and associated methods are provided for providing clock signals. The integrated oscillator preferably includes a micro-mechanical oscillating circuit for providing an oscillating clock signal. The micro-mechanical oscillating circuit preferably includes a support layer, a fixed layer positioned on a support layer, remaining portions of a sacrificial layer positioned only on portions of the fixed layer, and an oscillating layer positioned on the remaining portions of the sacrificial layer, overlying the fixed layer in spaced relation therefrom, and extending lengthwise generally transverse to a predetermined direction for defining a released beam for oscillating at a predetermined frequency. The spaced relation is preferably formed by removal of unwanted portions of the sacrificial layer.
    Type: Grant
    Filed: October 24, 1997
    Date of Patent: September 26, 2000
    Assignee: STMicroelectronics, Inc.
    Inventors: Tsiu Chiu Chan, Melvin Joseph DeSilva, Syama Sundar Sunkara
  • Patent number: 6094105
    Abstract: An oscillator having an adjustable output frequency comprises a resonator, an inverting amplifier coupled to the resonator, a variable capacitance coupled to the resonator and to the amplifier, and a shift register coupled to the variable capacitance. The variable capacitance comprises a first bank of switchable capacitors coupled to an input of the oscillator and a second bank of switchable capacitors coupled to an output of the oscillator. The shift register includes a plurality of bits and is configured such that the logic state of each bit determines the switching state of a corresponding capacitor from each bank of switchable capacitors. By shifting the bits in the shift register, the variable capacitance is varied, causing an adjustment in the output frequency of the oscillator.
    Type: Grant
    Filed: May 29, 1998
    Date of Patent: July 25, 2000
    Assignee: Intel Corporation
    Inventor: Thomas A. Williamson
  • Patent number: 6091307
    Abstract: A crystal tank circuit is connected between the ac cross-coupled outputs of two transistors that are selectively biased to an appropriate common mode voltage to cause rapid build-up of oscillation when the circuit is turned on and in which oscillation is sustained in the desired mode regardless of battery voltage fluctuation without wasting power. The differentially driven frequency-controlling crystal tank circuit receives balanced driving voltage excursions from the circuit.
    Type: Grant
    Filed: July 29, 1998
    Date of Patent: July 18, 2000
    Assignee: Lucent Techmologies Inc.
    Inventor: Dale Harvey Nelson
  • Patent number: 6064277
    Abstract: A drive circuit for an oscillator having an LC tank reduces phase noise by maximizing the oscillation amplitude and minimizing the drive to the tank. The drive circuit utilizes a capacitive attenuator network for level shifting the oscillation signal before feeding it back to the drive transistors in the drive circuit, thereby allowing a large peak voltage swing across the tank without saturating the transistors. An adaptive control circuit controls the biasing of the drive transistors and reduces the drive to the tank when the maximum oscillation amplitude is reached so that the drive circuit replenishes just the minimum amount of energy lost in the tank during each cycle, thereby minimizing the coupling of active circuit noise into the tank.
    Type: Grant
    Filed: February 27, 1998
    Date of Patent: May 16, 2000
    Assignee: Analog Devices, Inc.
    Inventor: Barrie Gilbert
  • Patent number: 6052036
    Abstract: A highly stable single chip crystal controlled oscillator with automatic gain control. An amplitude detector monitors the output of a crystal controlled oscillator amplifier and produces a feedback signal proportional to the output signal of the amplifier to ensure oscillation is induced at startup and that the amplitude of oscillation is limited to a preselected value during operation to conserve power consumption by the amplifier. The capacitor tank circuit connected to the input of the amplifier includes a voltage variable capacitor the voltage across which is initially established at manufacture to tune the oscillation frequency to a preselected value. The voltage across the voltage variable capacitor is also adjusted to compensate for temperature variations in the circuit.
    Type: Grant
    Filed: October 31, 1997
    Date of Patent: April 18, 2000
    Assignee: Telefonaktiebolaget L M Ericsson
    Inventors: H.ang.kan Enstrom, Erik Bengtsson, Torbjorn Gardenfors
  • Patent number: 6025757
    Abstract: There is disclosed an oscillator circuit comprising the first load capacitor with one electrode there of being connected with an input side of a CMOS inverter within a quartz oscillator circuit, and the second load capacitor with one electrode there of being connected with the output side of the inverter, wherein the inverter is coupled to a lower potential side via a current-limiting device, and the other electrodes of the first and second load capacitors are coupled to a lower potential side via the above-described current-limiting device. Thus, variations in the power-supply voltages synchronized with oscillation are reduced with realization of lower current consumption.
    Type: Grant
    Filed: November 13, 1998
    Date of Patent: February 15, 2000
    Assignee: Nippon Precision Circuits Inc.
    Inventors: Kunihiko Tsukagoshi, Satoru Miyabe, Kazuhisa Oyama
  • Patent number: 5999062
    Abstract: A crystal oscillator drive circuit controls the maximum amplitude of the drive signal to a crystal by limiting the bias current of a gm cell which senses the oscillation amplitude of the crystal. The bias current is commutated by the gm cell responsive to the crystal oscillation. The commuted current is converted to a single-ended current by a current mirror. An output stage converts the current to an output voltage having a voltage swing that is determined by the resistance of a load resistor. The output voltage is then fed back to drive the crystal through a positive feedback path. The output voltage swing and the drive signal to the crystal are limited by the bias current of the gm cell. A fully complementary implementation of the drive circuit includes two complementary gm cells, two current mirrors, and an output stage having two load resistors.
    Type: Grant
    Filed: February 27, 1998
    Date of Patent: December 7, 1999
    Assignee: Analog Devices, Inc.
    Inventor: Barrie Gilbert
  • Patent number: 5994969
    Abstract: A ring oscillator with differential delay stages employs an automatic gain control circuit producing a gain adjust signal that is responsive to a frequency control voltage applied to the ring oscillator. The effect of the frequency control voltage on the output voltage of the ring oscillator is counterbalanced by the gain adjust signal which prevents the output voltages of the delay stages from varying excessively over frequency. Further, the output stage of the ring oscillator includes shut off circuitry that allows the ring oscillator to be shut off in a non-oscillating mode in which it draws little current.
    Type: Grant
    Filed: December 22, 1997
    Date of Patent: November 30, 1999
    Assignee: Advanced Micro Devices, Inc.
    Inventor: Norman Bujanos
  • Patent number: 5966053
    Abstract: An improvement to a phase controlled mechanical oscillator consists of a balancing network which generates a feedback signal from two different input signals with adjustable weights. One of these input signals is directly derived from the oscillator signal, the other is derived from a phase tracking loop. Using the balancing network, adjustments can be made to adapt the feedback to the mechanical properties, in particular to the Q factor, of the oscillator. In a preferred embodiment, all major components are working at an intermediate frequency level, generated by mixing the oscillator frequency with a reference frequency. As a major advantage of this (heterodyne) mixing, the bandwidth of any applied frequency detector can be narrowed, thus increasing the achievable signal-to-noise ratio.
    Type: Grant
    Filed: January 20, 1998
    Date of Patent: October 12, 1999
    Assignee: International Business Machines Corporation
    Inventors: Urs Durig, Alain Stalder, Hansruedi Steinauer
  • Patent number: 5945883
    Abstract: A circuit for suppressing period jitter of the clock output of a ring oscillator caused by supply voltage fluctuations. The ring oscillator includes n identical current controlled delay circuits 26.1-n connected in a ring, and a replica circuit 36 identical to the current controlled delay circuit. The replica circuit 36 receives a constant input voltage so that its output is always at a high level. A differential amplifier 35 receiving a reference potential Vref is connected in a negative feedback circuit with replica circuit 36, so that the output of the replica circuit 36 is held equal to the reference potential Vref. An output of the negative feedback circuit is also applied to each of the current controlled delay circuits 26.1-n, so that their high level outputs are held equal to the reference potential Vref.
    Type: Grant
    Filed: December 5, 1997
    Date of Patent: August 31, 1999
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Hideaki Nagasawa, Atsuhiko Ishibashi
  • Patent number: 5936476
    Abstract: A CMOS super high speed voltage controlled oscillator (VCO) circuit that operates at frequencies of at least 3 GHz. The VCO circuit of the present invention includes a replica circuit, a first VCO cell coupled to the replica circuit, and a second VCO cell coupled to the first VCO cell and the replica circuit. A VCO output for transmitting a VCO output signal is also included. A first current source is coupled to the first VCO cell to transmit a first current from the power supply to the first VCO cell. A second current source is coupled to the second VCO cell to transmit a second current from the power supply to the second VCO cell. The first VCO cell and the second VCO cell each have respective first and second source follower load transistors coupled to the replica circuit. In addition, the first and second VCO cells, the first and second current sources, and the replica circuit are all fabricated using n-channel MOS transistors.
    Type: Grant
    Filed: November 18, 1997
    Date of Patent: August 10, 1999
    Assignee: VLSI Technology, Inc.
    Inventor: Kamran Iravani
  • Patent number: 5926071
    Abstract: A method is presented for minimizing the current consumption and the operating voltage of a voltage controlled oscillator. According to the invention the oscillator's (Q2) output signal (RFout) is detected as a DC voltage signal (Vgs) in a clamp/voltage multiplier circuit (U1, U2), preferably after a isolating amplifier (Q1). This detected signal is supplied in a feedback loop to a field effect transistor (FET1) controlling the oscillator's (Q2) current, whereby the field effect transistor controls the current (Ib) in the main current path to a predetermined minimum value. In this superimposed arrangement of the oscillator and the isolating amplifier the supply voltage (B) can be minimized by arranging, regarding the DC current, the isolating amplifier (Q1) in parallel with the field effect transistor (FET1) in the emitter branch of the oscillator (Q2).
    Type: Grant
    Filed: January 7, 1998
    Date of Patent: July 20, 1999
    Assignee: Nokia Mobile Phones
    Inventor: Osmo Kukkonen
  • Patent number: 5859573
    Abstract: The invention concerns oscillator circuits, more particularly coupling arrangements between an oscillator and an amplifier stage following the oscillator. The solution according to the invention optimizes the intensity of the coupling between the oscillator and the following amplifier stage so that the desired output level of the oscillator circuit is gained but the oscillator is loaded as little as possible. In the system according to the invention, the impedance value of the circuit element between the oscillator and the amplifier stage has been arranged to be automatically adjustable so that it is always adjusted to its smallest value, on which the desired output level of the oscillator coupling can still be gained. The coupling can, for example, be formed by means of a capacitance diode, the bias voltage of which is adjusted according to the direct voltage detected at the output level of the amplifier stage.
    Type: Grant
    Filed: July 23, 1997
    Date of Patent: January 12, 1999
    Assignee: Nokia Mobile Phones, Ltd.
    Inventor: Osmo Kukkonen
  • Patent number: 5834983
    Abstract: A bipolar negative resistance UHF oscillator having a voltage tunable resonator in its emitter circuit is operated at a fixed collector bias current and an RF detector is used as a convenient way to determine the RF current at which the oscillator is operating, by sensing the amplitude of the oscillator's output RF voltage across a constant load. An integrating error amplifier referenced to a desired detector output level responds to the actual detector output level to control the collector bias voltage for the oscillator and maintain the output of the oscillator at a fixed amplitude. Since the collector bias current is fixed, this keeps the operating point at fixed relation with respect to emitter cutoff. That relationship is chosen to be "just below" by initial selection of the constant collector bias current and the reference voltage used by the integrating error amplifier.
    Type: Grant
    Filed: September 30, 1997
    Date of Patent: November 10, 1998
    Assignee: Hewlett-Packard Company
    Inventor: Thomas M. Higgins, Jr.
  • Patent number: 5834982
    Abstract: Supplied with a power source, an output level of an oscillating circuit gradually increases until the oscillator circuit reaches its steady oscillation. A level monitor monitors the output level, and produces a control signal if the output level is less than a predetermined level. A current producing circuit receives the control signal and produces a boost current to increase a collector current at an oscillating transistor. The output level of the oscillating circuit suddenly increases as the collector current increases. After the output level of the oscillator reaches the predetermined level, the level monitor stops production of the control signal. Therefore, the boost current stops. As a result, the collector current of the oscillating transistor has a predetermined value dependent on the circuit structure of the oscillating circuit.
    Type: Grant
    Filed: August 29, 1997
    Date of Patent: November 10, 1998
    Assignee: Mitsumi Electric Co., Ltd.
    Inventors: Shigemitsu Watanabe, Hiromi Katoh
  • Patent number: 5825255
    Abstract: An oscillator in which the transconductance of an amplification transistor (T0) is limited through a measurement of the potential at the input electrode (G0) of the amplification transistor (T0) by means of a differential pair (T1, T2) for safeguarding the starting of the oscillator.
    Type: Grant
    Filed: July 29, 1997
    Date of Patent: October 20, 1998
    Assignee: U.S. Philips Corporation
    Inventor: Eise C. Dijkmans
  • Patent number: 5818306
    Abstract: A voltage control oscillation circuit for a CMOS which is capable of reducing phase noise and power consumption by adapting a voltage amplitude control loop and a common mode feedback circuit to a conventional LC-tank circuit. The circuit includes an LC-tank oscillation unit for outputting an oscillation voltage, an output common mode feedback unit for receiving an output from the LC-tank oscillation unit and eliminating a common mode noise of the output, and a voltage amplitude control unit for controlling a bias current of the LC-tank oscillation unit in accordance with a voltage difference at both ends of an LC-tank oscillation terminal which voltage is applied thereto through the output common mode feedback unit, for thus controlling the amount of an oscillation voltage.
    Type: Grant
    Filed: July 15, 1997
    Date of Patent: October 6, 1998
    Assignee: Electronics and Telecommunications Research Institute
    Inventors: Jong-Ryul Lee, Ook Kim, Jong-Kee Kwon, Chang-Jun Oh, Won-Chul Song, Kyung-Soo Kim
  • Patent number: 5801592
    Abstract: An oscillator circuit is provided for stabilizing the amplitude of a HF oscillation of an audio signal. In such an oscillator circuit, an audio signal having a frequency in the range of 20 Hz . . . 20 kHz is coupled into the oscillator circuit, is modulated with a high frequency and is emitted in the form of an RF audio signal having a frequency of more than 2 MHz. Such an oscillator circuit is used for instance in an infrared transmitting unit, wherein a low frequency audio signal is transformed into a higher frequency infrared signal. The higher frequency audio signals are transmitted via infrared channel to an appropriate receiving unit--for instance to infrared head phones--which comprises a receiving unit having an appropriate demodulator and preferably also a stereo-decoder in order to reproduce the low frequency audio signals.
    Type: Grant
    Filed: May 21, 1997
    Date of Patent: September 1, 1998
    Assignee: Sennheiser electronic GmbH & Co. KG
    Inventors: Wolfgang Mann, Horst Schaefer
  • Patent number: 5796313
    Abstract: A novel ring oscillator integrated circuit whose frequency of oscillation is independent of supply voltage, temperature and process technology is described. In addition, the ring oscillator circuit consumes low power and its frequency of oscillation is programmable. The ring oscillator comprises one or more inverter sections cascaded together in series. The output of the final inverter stage is coupled to the input of the first inverter stage. Inserted in the feedback loop is feedback control circuitry which functions to control the start/stop operation of the oscillator. Each inverter section includes a p-channel transistor coupled to a parallel combination of impedance and capacitance, which gives the inverter section asymmetric operating characteristics. This asymmetry helps to achieve a frequency of oscillation independent of supply voltage. A plurality of transistors having predetermined impedance's are coupled in series with the p-channel transistor to form the current limiting impedance.
    Type: Grant
    Filed: April 25, 1996
    Date of Patent: August 18, 1998
    Assignee: Waferscale Integration Inc.
    Inventor: Boaz Eitan
  • Patent number: 5770980
    Abstract: A low power, fast starting oscillator (10) of the Colpitts type includes an amplifier (12) that provides voltage gain and feeds a source follower circuit (14) that provides a desirable output impedance. A crystal (16) is coupled from an output of the source follower circuit (14) back to the amplifier's input (32). The voltage gain of the amplifier (12) and the output impedance of the source follower circuit (14) are independently selectable to provide an optimum transconductance for the oscillator (10) to start quickly. When oscillations reach a threshold value, the transconductance may be reduced to save power.
    Type: Grant
    Filed: December 23, 1996
    Date of Patent: June 23, 1998
    Assignee: Motorola, Inc.
    Inventors: Raymond Louis Barrett, Jr., John Wayne Simmons, Barry Herold, Grazyna A. Pajunen
  • Patent number: 5764110
    Abstract: A circuit for suppressing period jitter of the clock output of a ring oscillator caused by supply voltage fluctuations. The ring oscillator includes n identical current controlled delay circuits 26.1-n connected in a ring, and a replica circuit 36 identical to the current controlled delay circuit. The replica circuit 36 receives a constant input voltage so that its output is always at a high level. A differential amplifier 35 receiving a reference potential Vref is connected in a negative feedback circuit with replica circuit 36, so that the output of the replica circuit 36 is held equal to the reference potential Vref. An output of the negative feedback circuit is also applied to each of the current controlled delay circuits 26.1-n, so that their high level outputs are held equal to the reference potential Vref.
    Type: Grant
    Filed: December 20, 1996
    Date of Patent: June 9, 1998
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Atsuhiko Ishibashi
  • Patent number: 5714911
    Abstract: A quadrature oscillator includes an amplitude control circuit that is based upon the trigonometric identity sin.sup.2 .omega.t+cos.sup.2 .omega.t=1. The amplitude control circuit, referred to as a Pythagorator, includes two squaring circuits. Each squaring circuit receives a respective quadrature oscillator signal and squares it. The outputs of the two squaring circuits are joined together so as to sum the outputs of the two squaring circuits to produce a sum of squares signal. This signal, a current in the preferred embodiment, is provided to damping diodes coupled to the outputs of the quadrature oscillator. The damping diodes produce a shunt positive resistance at the outputs of the quadrature oscillator in response to this current that has the effect of cancelling the shunt negative resistance of the regenerative elements of the oscillator thereby establishing the amplitude of the quadrature oscillator signals at a desired amplitude.
    Type: Grant
    Filed: February 6, 1996
    Date of Patent: February 3, 1998
    Assignee: Analog Devices
    Inventor: Barrie Gilbert
  • Patent number: 5708394
    Abstract: An apparatus and method are disclosed for improving the stability of the frequency of vibration of an oscillator signal produced by an oscillator circuit. In a preferred embodiment of the present invention, a quartz crystal resonator is one arm of a bridge which generates a bridge signal which varies in accordance with the vibrating frequency of the resonator. A synchronous demodulator responds to the bridge signal for producing an error signal which is converted into a control signal. A control circuit receives the control signal and changes its reactance when the resonator is no longer vibrating at its unperturbed resonance frequency so that the vibration frequency of the resonator connected to the control circuit is returned to its resonant frequency. An automatic level control circuit is also included for controlling the drive level of the signal exciting the resonator.
    Type: Grant
    Filed: July 1, 1996
    Date of Patent: January 13, 1998
    Assignee: Hewlett-Packard Company
    Inventor: Richard K. Karlquist
  • Patent number: 5663690
    Abstract: A method is described for maintaining a constant Q in a voltage controlled oscillator (VCO) which is tuned over a broad frequency band. A tank circuit (111) sets a center frequency of an oscillator circuit (112). A variable reactance circuit (113) provides a variable effective reactance across the tank circuit (111) corresponding to an applied tuning voltage (117) for tuning the VCO. Resistive currents from the variable reactance circuit are rectified by a rectification circuit (120). A comparator produces a Q control voltage corresponding to the rectified resistive currents and a reference current Iref at a terminal (126) which is coupled to a variable resistance circuit (122) for supplying differential resistive currents to the tank circuit (111) which offset the resistive currents from the variable reactance circuit, thereby maintaining a constant Q in the VCO.
    Type: Grant
    Filed: March 6, 1996
    Date of Patent: September 2, 1997
    Assignee: Motorola, Inc.
    Inventor: Michael McGinn
  • Patent number: 5606294
    Abstract: An automatic gain control circuit and method ensure feedback for oscillator circuitry fabricated on a single semiconductor chip to adapt to the Q value established by a resonator circuit connected to the oscillator circuitry, and to ensure that gain is maximized and linearity of operation preserved within the voltage rails of the power supply.
    Type: Grant
    Filed: January 29, 1996
    Date of Patent: February 25, 1997
    Assignee: IC Works, Inc.
    Inventor: Roy Richards