Phase Shift Oscillator Patents (Class 331/108B)
  • Patent number: 6137370
    Abstract: An oscillator having a feedback loop circuit formed by two transductors and one amplifier, and two capacitors respectively connected to the outputs of these transconductors. The transconductors and the amplifier are constructed by common-source configuration transistors to which common bias current is supplied. Since they have invert characteristics for the input voltage, the feedback loop is also self-biased by means of negative feedback operation. The oscillation signal is outputted from an arbitrary position on the feedback loop of the oscillator. According to the oscillator as constituted, the oscillation frequency can be controlled in a wide range by varying the bias current to the common-source transistors.
    Type: Grant
    Filed: January 22, 1999
    Date of Patent: October 24, 2000
    Assignee: Kabushiki Kaisha Toshiba
    Inventor: Takeshi Yamamoto
  • Patent number: 6025765
    Abstract: A gyrator includes shunt or feedback nodal capacitors and shunt lossy inductors without shunt load resistors. The effective nodal capacitance is reduced by the introduction of the shunt lossy inductors. The inductors act to discriminate against injected power supply noise, resulting in improved oscillator phase noise. The inductors produces less drop dc voltage than the resistive load, so that larger linear oscillation is obtained with improved oscillator phase noise.
    Type: Grant
    Filed: April 8, 1998
    Date of Patent: February 15, 2000
    Assignee: Nortel Networks Corporation
    Inventor: Anthony Kevin Dale Brown
  • Patent number: 6018219
    Abstract: A small and economically fabricated CMOS voltage controlled crystal oscillator is provided by coupling three inverter amplifiers in series with a regenerative crystal controlled feedback loop. The first and second CMOS inverters have output nodes whose impedances are modified by a CMOS impedance modulating circuit. Also coupled to each of these two output nodes is a CMOS transistor shunt capacitor. The impedance of the output node is modified according to the magnitude of a voltage control signal applied to the CMOS modulating circuits. The self-bias of the modulating circuits is maintained substantially constant by adjusting the gate drive in each of the modulating circuits according to gate drives derived from a dummy modulating circuit.
    Type: Grant
    Filed: June 24, 1999
    Date of Patent: January 25, 2000
    Assignee: Creative Integrated Systems
    Inventors: James A. Komarek, Jack L. Minney, Stephen P. Nordine, Harold F. Lewis, Richard Wada, John F. Stockman
  • Patent number: 5982248
    Abstract: An integrated circuit configuration for producing a clock signal includes an integrated inverter connected between an input terminal and an output terminal. A crystal is externally connected to the oscillator circuit. A feedback path of the inverter contains a phase-shifting element which effects a phase shift through 180.degree., so that conditions for oscillation continue to be provided if the crystal breaks.
    Type: Grant
    Filed: October 29, 1998
    Date of Patent: November 9, 1999
    Assignee: Siemens Aktiengesellschaft
    Inventor: Wolfgang Wagner
  • Patent number: 5912596
    Abstract: A method and system in an integrated circuit for frequency tuning oscillator circuits. An oscillator circuit within an integrated circuit is formed on a substrate such that the oscillator circuit is coupled to an inductor component. The inductor component includes a first inductor positioned parallel to a second inductor such that a total effective inductance is associated with the first and second inductors. The first inductor is formed from a first spiral coil layer which is coupled to a second spiral coil layer on the substrate. The second inductor is formed of a single spiral coil layer on the substrate, wherein the single spiral coil layer provides an inductive feedback signal to the oscillator circuit when electrical current flows through the single spiral coil layer in response to current flowing through the first spiral coil layer and the second spiral coil layer.
    Type: Grant
    Filed: January 26, 1998
    Date of Patent: June 15, 1999
    Assignee: International Business Machines Corporation
    Inventor: Uttam Shymalindu Ghoshal
  • Patent number: 5852385
    Abstract: A voltage controlled oscillator circuit comprises a first lowpass OTA-C filter with differential input and differential output and a second lowpass OTA-C filter with differential input and differential output. A non-inverted output terminal of the first OTA-C filter is connected with a non-inverted input terminal of the second OTA-C filter, an inverted output terminal of the first OTA-C filter is connected with an inverted input terminal of the second OTA-C filter, a non-inverted output terminal of the second OTA-C filter is connected with an inverted input terminal of the first OTA-C filter, and an inverted output terminal of the second OTA-C filter is connected with a non-inverted input terminal of the first OTA-C filter. Gate widths of input terminals of OTAs in each OTA-C filter are set appropriately, and initial values of terminals are set by nMOSFETs 3-6, and oscillation output is outputted from the non-inverted output terminal and the inverted output terminal of the second OTA-C filter.
    Type: Grant
    Filed: September 17, 1997
    Date of Patent: December 22, 1998
    Assignee: NEC Corporation
    Inventor: Masanori Izumikawa
  • Patent number: 5734299
    Abstract: A transconductance amplifier for use in a low noise, microwave voltage controlled oscillator. The transconductance amplifier incorporates a linear amplifier having ratioed transistors to provide linearized gain. A tuning arrangement combines in-phase and out of phase currents in an inverse ratio to provide a constant D.C. current sum. The tuning circuit has been arranged to operate without a cascode stage such that the power supply voltage requirement is reduced from 5.0 volts to 3.3 volts.
    Type: Grant
    Filed: July 25, 1996
    Date of Patent: March 31, 1998
    Inventor: Anthony Kevin Dale Brown
  • Patent number: 5712599
    Abstract: An oscillating signal generator for generating an oscillating signal having a variable oscillation frequency that can be near the unity gain frequency of the gain devices within the oscillating signal generator (Generation of High-Frequency Oscillating Signal Techniques, "GHOST"). Two gain stages, each with a respective effective resistance R.sub.eff, an emitter load capacitance C.sub.E, and a respective gain device having a unity gain frequency .omega..sub.T, are cascaded and configured to provide a respective gain with a phase at substantially 180.degree.. In that case, the oscillation frequency, of the oscillating signal generated by the oscillating signal generator of the present invention, .omega.=?.omega..sub.T /(R.sub.eff C.sub.E)!.sup.1/2. A feedback with a feedback gain is provided between the output to the input of the cascade of the two gain stages. The feedback gain is designed such that a product of the feedback gain and the gain through the cascade of the two gain stages is substantially one.
    Type: Grant
    Filed: June 19, 1996
    Date of Patent: January 27, 1998
    Inventor: Leonard L. Kleinberg
  • Patent number: 5712601
    Abstract: An oscillation circuit is provided which is easily adjusted with a high degree of accuracy. The oscillation circuit including a filter having a time constant and an inverting amplifier which feeds back the output of the filter to the input side of the filter so that an oscillation condition is fulfilled. The filter includes a gm amplifier formed of a differential amplifier, and a capacitor. The constant current source of the differential amplifier is connected to a free running oscillation frequency adjusting circuit. The adjusting circuit includes a microcomputer, a decoder which decodes the output data of the microcomputer and a switching circuit driven by the output of the decoder and varying the current value according to the output of the decoder. A current in accordance with a current value depending on the setting of the switch flows through the constant current source.
    Type: Grant
    Filed: February 22, 1996
    Date of Patent: January 27, 1998
    Assignee: Rohm Co. Ltd.
    Inventors: Yoshikazu Shimada, Isoshi Takeda
  • Patent number: 5652549
    Abstract: A monolithically integrated oscillator is implemented as ring oscillator with a line driver and a double line formed on one and the same chip. A running time of the double line is selected optimally long and a delay time of the line driver is selected optimally short. The double line can be loaded with controllable capacitors.
    Type: Grant
    Filed: March 1, 1996
    Date of Patent: July 29, 1997
    Assignee: Siemens Aktiengesellschaft
    Inventors: Reinhold Unterricker, Bjoern Heppner
  • Patent number: 5635880
    Abstract: A microwave differential amplifier comprises a first and a second matched NMOS device, each connected with the source to a common bias node, the gate to an input port for receiving a differential input signal and with the drains to an output port for providing a differential output signal. The Miller capacitors of each device provide the necessary feedback between the input and output ports for shifting the phase of the differential output signal with respect to the phase of the differential input signal with 45.degree. at a predetermined frequency. The operating point of the NMOS devices is maintained in the linear region of the respective transfer characteristic, using matched loads and a corresponding bias current. The loads may be resistors, in which case AGC is used for maintaining a constant bias current, or active loads. A VCO built with four such differential amplifiers in a gyrator configuration oscillates at the predetermined frequency and has eight output signals.
    Type: Grant
    Filed: March 14, 1996
    Date of Patent: June 3, 1997
    Assignee: Northern Telecom Limited
    Inventor: Anthony K. D. Brown
  • Patent number: 5629652
    Abstract: Both differential and single-ended band-switchable VCOs are described. The single-ended version of the voltage controlled oscillator in its most basic form includes a load, two transistors, two delay elements, and a switchable current source. The first transistor includes a collector, an emitter and a base coupled to the load to form an output terminal for providing an oscillator output signal. The first delay element is connected between the collector and the base of the first transistor. The second transistor includes a collector, an emitter and a base connected to the base of the first transistor. The second delay element is connected between the collector of the first transistor and the collector of the second transistor.
    Type: Grant
    Filed: May 9, 1996
    Date of Patent: May 13, 1997
    Assignee: Analog Devices
    Inventor: Frederick G. Weiss
  • Patent number: 5608360
    Abstract: Multiple resonator stages are connected in series to form a closed loop. Each of these cascaded resonator stages includes at least a high frequency resonator and an amplifier. The amplifier amplifies the output of the high frequency resonator. Each stage also includes a power divider connected to the amplifier output. The power divider has at least two outputs. One of the two power divider outputs serves as an output of the oscillator formed by the cascaded resonator stages. The other output of the power divider is connected to the input of the next high frequency resonator stage. The oscillator further includes a phase shifter connected between two of the high frequency resonator stages to achieve a closed loop phase shift of N(360) degrees at the oscillator operating frequency, where N is an integer. The high frequency resonators may be acoustic resonators such as surface acoustic wave resonators (SAWR).
    Type: Grant
    Filed: November 3, 1995
    Date of Patent: March 4, 1997
    Assignee: Northrop Grumman Corporation
    Inventor: Michael M. Driscoll
  • Patent number: 5581215
    Abstract: A voltage controlled oscillator that completely eliminates the need for any externally mounted coil and capacitor includes a first loop and a second loop. The first loop provides band-limiting of an output signal of an amplifier through a bandpass filter to provide oscillation at a frequency of a resonant point of the bandpass filter, and the second loop controls the oscillation amplitude, so that a lowpass filter output with a 90.degree. phase is extracted from the first loop, while a bandpass filter output with a 0.degree. phase is extracted from the second loop. The voltage controlled oscillator may be used in an automatic fine tuning circuit for television.
    Type: Grant
    Filed: June 20, 1995
    Date of Patent: December 3, 1996
    Assignee: Motorola, Inc.
    Inventor: Hiroshi Ogasawara
  • Patent number: 5546056
    Abstract: An injection-locked oscillator having a non-reciprocal four-port network with a pair of input ports (1, 2) and a pair of output ports (3, 4) in which the signal transfer path from a first input port (1) to a first output port (3) is non-reciprocal, the signal transfer path from a second input port (2) to a second output port (4) is non-reciprocal, the signal transfer path from a second input port (2) to a first output port (3) is non-reciprocal, and an amplifier with the input port coupled with said first output port and the output port coupled with said second input port, is locked to an injection signal applied to said first input port and provides oscillation output to said second output port (4). The circuit between the first input port (1) and the second input port (2), and the circuit between the first output port (3) and the second output port (4) are isolated. The present oscillator is implemented in a small IC chip, and has feature to be injection-locked in wide frequency band.
    Type: Grant
    Filed: January 27, 1995
    Date of Patent: August 13, 1996
    Assignee: Nippon Telegraph and Telephone Corporation
    Inventor: Tsuneo Tokumitsu
  • Patent number: 5543742
    Abstract: A phase shifting circuit has an oscillation circuit. The oscillation circuit is provided with a charging and discharging capacitor at which the oscillation signal is generated. The oscillation signal has a constant level period and a saw tooth wave period. A valve of current flowing through the capacitor is changed in the middle of the saw tooth wave period by an input signal. An output of the phase shifting circuit is phase-shifted by 90.degree. with respect to the input signal.
    Type: Grant
    Filed: September 15, 1994
    Date of Patent: August 6, 1996
    Assignee: Rohm Co., Ltd.
    Inventors: Isoshi Takeda, Yoshikazu Shimada
  • Patent number: 5483195
    Abstract: A low noise linear amplifier and a microwave voltage controlled oscillator constructed from such amplifier. Each amplifier within the VCO utilizes a ratioed transistor configuration to generate a linear output over a wide range of inputs. Output current from the amplifier is split into a main output current and components of in-phase and 180.degree. out-of-phase current. A logarithmic tuning control combines the components of in-phase and 180.degree. out-of-phase currents in inverse ratio to provide a constant d.c. feedback current.
    Type: Grant
    Filed: October 20, 1994
    Date of Patent: January 9, 1996
    Assignee: Northern Telecom Limited
    Inventor: Anthony K. D. Brown
  • Patent number: 5459438
    Abstract: This invention relates to oscillators employing a primary feedback network and a high pass filter feedback network. The feedback networks are connected between the input and output of a of a high signal gain amplifier system. The primary feedback network provides positive feedback to cause oscillation to occur and also determines the nominal frequency of oscillation. The high pass filter feedback network provides a negative feedback signal that controls the rise and fall time of the amplifier system's output signal. By varying the output signal's rise and fall time the frequency of oscillation is also changed. The high signal gain amplifier system operates with one or more amplifier stages in the non-linear region to produce a significantly distorted sine wave or pulse output signal.
    Type: Grant
    Filed: December 16, 1992
    Date of Patent: October 17, 1995
    Inventor: Fred Mirow
  • Patent number: 5450039
    Abstract: An integrated circuit has a self-contained voltage control oscillation circuit wherein the oscillating frequency is controlled according to a control voltage; The circuit includes a first oscillation circuit which forms a first oscillation loop including a first amplifier for generating a first output signal with an oscillating frequency which is controlled according to an operating current of the first amplifier and a second oscillation circuit which forms a second oscillation loop including a second amplifer for generating a second output signal with an oscillating frequency which is controlled according to an operating current of the second amplifer; A circuit for generating a control voltage controls the operating currents of the first and second amplifers and a current regulating circuit for generating an operating current regulating signal regulates the operating currents of the first and second amplifers.
    Type: Grant
    Filed: September 23, 1993
    Date of Patent: September 12, 1995
    Assignee: Rohm Co., Ltd.
    Inventors: Isoshi Takeda, Shigeyoshi Hayashi
  • Patent number: 5446418
    Abstract: A ring oscillator according to the invention includes a plurality of inverters cascade-connected between an input node and an output node. Each inverter includes four transistors connected in series between a power supply node and a ground node. A first pair of transistors each have a channel sized to have an input capacitance for delaying the signal of a preceding stage inverter for a prescribed time period. A second pair of transistors are coupled to a current mirror circuit and limits current flowing through the first pair of transistors. Thus, power consumption for obtaining a signal in a prescribed cycle is reduced.
    Type: Grant
    Filed: November 5, 1993
    Date of Patent: August 29, 1995
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventors: Motoko Hara, Takeshi Kajimoto
  • Patent number: 5414392
    Abstract: An electrical circuit comprising means for receiving an input signal for encoding or modulating and amplification. Multiple amplification stages including at least one transconductance amplifier are provided. There are means for having the input signal modulate the oscillator constituted by the multiple amplification stages to provide a 360.degree. phase-shifted signal at a predetermined frequency. Gain control means are also provided for developing level for permitting oscillation under conditions including at least the conditions of turn on of the circuit and other operating conditions. The gain control means includes a transistor and resistor network for adjusting the gain to sustain the oscillation. The transistor and resistor also regulate amplification of an intermediate stage of the amplifier. The preamplifier directly converts an EKG and/or other signals to linearized control currents which modulate the oscillator.
    Type: Grant
    Filed: August 26, 1993
    Date of Patent: May 9, 1995
    Assignee: MedCom Electronics
    Inventor: Leonard Schupak
  • Patent number: 5359298
    Abstract: The voltage controlled oscillator in a phase-locked loop comprises a voltage-current converter (62) and a current frequency converter (34). The voltage-current converter (62) comprises a voltage differential-current converter (64), a current-current converter (66) and a current adder-subtracter (68). In the voltage differential-current converter (64), only the voltage fluctuation or difference .DELTA.V.sub.CN with respect to one half a power supply voltage V.sub.DD /2, and not the absolute value of a control voltage V.sub.CN, undergoes current conversion as a control current I.sub.CN. Therefore, the center frequency of the oscillation frequency is not a factor of control voltage V.sub.CN and is controlled only by an offset voltage V.sub.B2. Accordingly, the center frequency can be independently set by changing offset voltage VB.sub.2. This is particularly significant in zone bit recording, which requires a wide frequency band.
    Type: Grant
    Filed: December 29, 1993
    Date of Patent: October 25, 1994
    Assignee: Seiko Epson Corporation
    Inventor: Akira Abe
  • Patent number: 5352993
    Abstract: A voltage controlled surface acoustic wave oscillator includes an integrated circuit and a two port resonator connected as a feedback element around the integrated circuit. The integrated circuit includes a phase shifting network and an amplifier directly connected to the phase shifting network.
    Type: Grant
    Filed: September 30, 1992
    Date of Patent: October 4, 1994
    Assignee: Telefonaktiebolaget L M Ericsson
    Inventor: Heinz B. Mader
  • Patent number: 5317287
    Abstract: A multirange low-gain voltage controlled ring oscillator generates a substantially temperature-independent oscillator signal. Each frequency range is formed by utilizing a selected value of a voltage variable resistance in each stage of the ring oscillator. The oscillator signal is made to be substantially temperature-independent by utilizing a substantially temperature-independent constant current source to source a fixed current through the variable resistance and a temperature varying current which sinks and sources additional current to the oscillating circuit as temperature rises and falls, respectively.
    Type: Grant
    Filed: July 16, 1992
    Date of Patent: May 31, 1994
    Assignee: National Semiconductor Corporation
    Inventor: Michael A. Brown
  • Patent number: 5302920
    Abstract: An electrically controlled oscillator circuit having multi-phase outputs with programmable frequency. The circuit includes a ring oscillator having a plurality of inverting stages. Each stage has an output which is connected to a switch that can be programmed to select one of a plurality of capacitors with different values to change the frequency range of the oscillator. Controlled current is fed to the stages to vary the frequency of the oscillator within a selected frequency range. Using capacitors to change the frequency range of the oscillator reduces variations of the oscillator output frequency.
    Type: Grant
    Filed: October 13, 1992
    Date of Patent: April 12, 1994
    Assignee: NCR Corporation
    Inventor: Ricky F. Bitting
  • Patent number: 5302919
    Abstract: The voltage-controlled oscillator in a phase-locked loop comprises a voltage-current converter (62) and a current frequency converter (34). The voltage-current converter (62) comprises a voltage differential-current converter (64), a current-current converter (66) and a current adder-subtracter (68). In the voltage differential-current converter (64), only the voltage fluctuation or difference .DELTA.V.sub.CN with respect to one-half a power supply voltage V.sub.DD /2, and not the absolute value of a control voltage V.sub.CN, undergoes current conversion as a control current I.sub.CN. Therefore, the center frequency of the oscillation frequency is not a factor of control voltage V.sub.CN and is controlled only by an offset voltage V.sub.B2. Accordingly, the center frequency can be independently set by changing offset voltage V.sub.B2. This is particularly significant in zone bit recording, which requires a wide frequency band.
    Type: Grant
    Filed: August 20, 1992
    Date of Patent: April 12, 1994
    Assignee: Seiko Epson Corporation
    Inventor: Akira Abe
  • Patent number: 5300898
    Abstract: A differential inverter such as may be used in an oscillator circuit. The differential inverter is connected between first and second current sources. The differential inverter includes first and second single signal CMOS inverters connected in parallel between the first and second controlled current sources. Each of the current sources is a MOS transistor. A bias circuit is connected to the control gates of the MOS transistors and provides bias signals thereto, the bias circuit includes a variable current source with bias signals being generated in response to the current flow in the variable current source.
    Type: Grant
    Filed: July 29, 1992
    Date of Patent: April 5, 1994
    Assignee: NCR Corporation
    Inventors: Dao-Long Chen, Robert D. Waldron
  • Patent number: 5298870
    Abstract: A voltage controlled oscillator comprises a plurality of differential amplification stages each arranged to introduce a phase shift between its differential input signal and its differential output signal. The frequency at which the desired phase shift occurs can be controlled by adjusting the control signal Vc. The stages are arranged such that the output of one amplifier becomes the input to the next amplifier, making the phase shift additive. Further, a phase shift of 180.degree. may be introduced by inverting the output from one stage before inputting it to the next stage. The total phase shift introduced by the stages is 360.degree.. In this way, an oscillating signal of varying phase shift is produced at the output of each stage. Each stage comprises a standard differential amplifier, well known in the art, having a matched pair of p-channel transistors and a matched pair of n-channel transistors.
    Type: Grant
    Filed: July 6, 1992
    Date of Patent: March 29, 1994
    Assignee: Inmos Limited
    Inventors: Christopher Cytera, Andrew M. Hall
  • Patent number: 5285173
    Abstract: A ring-type oscillator with a plurality of delay cells including differential pairs of MOS transistors. Current sources supply current to each pair, and the magnitude of the current supplied is variable by a control voltage to alter the delay of the MOS devices, thereby to alter the frequency of oscillation. Each delay cell MOS device is connected in series with another MOS device biased into its linear region to act as a load resistance. This load is variable by the control voltage so as to tend to maintain the gain of the delay cells constant with changes in frequency of oscillation.
    Type: Grant
    Filed: July 13, 1992
    Date of Patent: February 8, 1994
    Assignee: Analog Devices, Inc.
    Inventor: David C. Reynolds
  • Patent number: 5272453
    Abstract: A method and apparatus for switching between gain curves of a switched gain voltage controlled oscillator (VCO) 52, 52' or 52". In one form, the present invention uses a switched gain voltage controlled oscillator (VCO) 52, 52' or 52" which utilizes a ring oscillator. A Gain Control signal is used to select between using a high gain curve and using a low gain curve. The low gain curve is produced by selecting a high resistance path to either power or ground. The high gain curve is produced by selecting a low resistance path to either power or ground.
    Type: Grant
    Filed: August 3, 1992
    Date of Patent: December 21, 1993
    Assignee: Motorola Inc.
    Inventors: Kevin M. Traynor, Hengwei Hsu, Kenneth R. Burch
  • Patent number: 5262735
    Abstract: A ring oscillator comprises a plurality of amplifiers connected in a multi-stage connection and each including a pair of output terminals from which first output signals are issued respectively; a pair of input terminals to which another pair of output terminals of a last stage amplifier are connected, respectively, and an amplifying circuit arranged between the output terminals and the input terminals. An oscillating signal can be generated by taking out the respectively corresponding second output signals from the amplifiers and combining these second output signals. The ring oscillator is constructed such that the second output signals are taken out from any middle output terminals in the amplifying circuit, other than the output terminals and the input terminals.
    Type: Grant
    Filed: July 20, 1992
    Date of Patent: November 16, 1993
    Assignee: Fujitsu Limited
    Inventors: Yasuhiro Hashimoto, Katsuya Ishikawa, Chikara Tsuchiya
  • Patent number: 5241286
    Abstract: A FET oscillator with increased frequency stability. This is accomplished by using a controlled voltage supply to power the amplifier stage of the oscillator. This voltage changes as the FET amplifier temperature increases in order to reduce the variation in frequency, caused by the amplifier's gain and phase shift changes. By using this compensated amplifier as the active section of an oscillator, the oscillator frequency stability is increased.
    Type: Grant
    Filed: September 28, 1992
    Date of Patent: August 31, 1993
    Inventor: Fred Mirow
  • Patent number: 5239274
    Abstract: Differential buffers are used in a voltage-controlled oscillator to provide pairs of complementary phase signals. The preferred arrangement includes a ring of the differential buffers. Each differential buffer has a current control input, and the current control inputs of the buffers are all connected to a control voltage input to simultaneously adjust the propagation delay of each of the buffers. In contrast to a conventional ring oscillator, which has an odd number of stages, a ring oscillator made of differential buffers can have an even number of buffers to provide a number of phases that is a multiple of four. The differential buffer preferably includes a pair of CMOS inverters sharing a common PMOS current sourcing transistor and a common NMOS current sinking transistor.
    Type: Grant
    Filed: May 26, 1992
    Date of Patent: August 24, 1993
    Assignee: Digital Equipment Corporation
    Inventor: Kuang K. Chi
  • Patent number: 5191301
    Abstract: A highly stable, high frequency voltage controlled oscillator (VCO) for phase locked loops is adapted to be fully integrated on a single silicon chip and is operable over a wide frequency range without using off-chip capacitors. The VCO is a fully differential ring oscillator with fully differential voltage control. The VCO is constructed from basic blocks made of differential emitter coupled transistor pairs. Voltage control is provided by differential d.c. amplifiers which vary the capacitive load seen by the logic blocks.
    Type: Grant
    Filed: May 12, 1992
    Date of Patent: March 2, 1993
    Assignee: International Business Machines Corporation
    Inventor: Allan L. Mullgrav, Jr.
  • Patent number: 5185581
    Abstract: A differential amplifier includes a bias current source and a current dividing circuit for controllably dividing a bias current between first and second current paths. A first pair of matched transistors is connected as a differential pair between matched load impedances and the first current path. A second pair of matched transistors is connected as a differential pair between the matched load impedances and the second current path. Differential inputs of the second differential pair are connected to corresponding differential inputs of the second differential pair. The transistors of the first and second pairs have different emitter areas. Matched capacitors may be connected between respective differential inputs and differential outputs of the differential amplifier. The load impedances may be tapped to provide outputs having a lower differential gain. The differential amplifier is useful for building resonant circuits, for example voltage controlled oscillators having high Q factors.
    Type: Grant
    Filed: March 26, 1992
    Date of Patent: February 9, 1993
    Assignee: Northern Telecom Limited
    Inventor: Anthony K. D. Brown
  • Patent number: 5172076
    Abstract: A resonant circuit comprises first and second amplifiers. An input of the second amplifier is coupled to an output of the first amplifier, and an output of the second amplifier is cross-coupled to an input of the first amplifier. The first amplifier has a first gain and a 90 degree phase shift between its input and its output at a resonant frequency of the resonant circuit. The second amplifier has a second gain and a 90 degree phase shift between its input and its output at the resonant frequency of the resonant circuit. The second gain is different from the first gain. The resonant circuit can have a first port and second ports coupled to an input and an output respectively of one of the first and second amplifiers. Because the gains of the first and second amplifiers differ, the gain from the first port to the second port of the resonant circuit will differ from the gain from the second port to the first port.
    Type: Grant
    Filed: March 26, 1992
    Date of Patent: December 15, 1992
    Assignee: Northern Telecom Limited
    Inventor: Anthony K. D. Brown
  • Patent number: 5093634
    Abstract: A clamped linear transconductance amplifier path, consisting essentially of a current clamp merged in a linear transconductance amplifier path, is used in a triple-input, triple-output transconductor (200). In a balanced transconductor in CMOS technology, this clamped linear transconductance amplifier path is formed by a p-channel MOS transistor (M23) separately connected in series with each of a matched pair of p-channel MOS transistors (M21,M22). The clamped linear transconductance amplifier path, together with two other transconductance paths (M15-M20; M9-M14), can be interconnected to form the input side of the triple-input, triple-output transconductor (200). By summing and integrating the outputs of the input side of the triple-input transconductor (200), the output (V.sub.OUT,P and V.sub.OUT,N) of the output side of the transconductor can be formed. By feeding back this output to the input side of the transconductor (200), an oscillator can be obtained.
    Type: Grant
    Filed: October 31, 1990
    Date of Patent: March 3, 1992
    Assignee: AT&T Bell Laboratories
    Inventor: John M. Khoury
  • Patent number: 5093635
    Abstract: Controllable oscillator circuit comprising a regenerative loop which incorporates a cascade circuit of first and second sections each having a controllable gain and a phase shift which is 90.degree. at the oscillation frequency, and an amplitude detection arrangement which is coupled between an output and a control input of at least one of the two sections.
    Type: Grant
    Filed: April 9, 1991
    Date of Patent: March 3, 1992
    Assignee: U.S. Philips Corporation
    Inventors: Wolfdietrich G. Kasperkovitz, Hendricus C. De Ruijter
  • Patent number: 5081428
    Abstract: A voltage controlled oscillator (VCO) generates a 50% duty cycle clock. The 50% duty cycle clock is derived directly from the operating frequency of the VCO thereby abating the need for the VCO to operate at twice the desired clock frequency. This allows the VCO to be utilized in high frequency phase-locked loop systems.
    Type: Grant
    Filed: March 29, 1991
    Date of Patent: January 14, 1992
    Assignee: Codex Corp.
    Inventors: Ahmad H. Atriss, Benjamin C. Peterson, Lanny L. Parker
  • Patent number: 5081429
    Abstract: A voltage controlled oscillator (VCO) includes a voltage controlled load. The voltage controlled load supplies additional capacitive loading to the VCO, via a transmission gate, at low frequencies to decrease the frequency-gain factor of the VCO. Moreover, at high frequencies, the effect of the voltage controlled load is minimized by turning off the transmission gate thereby allowing the VCO to operate at maximum frequency for worst case speed conditions.
    Type: Grant
    Filed: March 29, 1991
    Date of Patent: January 14, 1992
    Assignee: Codex Corp.
    Inventors: Ahmad H. Atriss, Benjamin C. Peterson, Lanny L. Parker
  • Patent number: 5061907
    Abstract: The present invention provides a high frequency CMOS voltage controlled oscillator circuit with gain constant and duty cycle compensation. The voltage controlled oscillator circuit includes a multi-stage ring oscillator that includes a plurality of series-connected inverter stages comprising N-channel and P-channel transistors. The ring oscillator responds to a control current signal for controlling the frequency of oscillation of the ring oscillator. A voltage-to-current converter converts a tuning voltage input signal to a corresponding output current signal that is independent of the channel strength of the N-channel and P-channel transistors. Process compensation circuitry responds to the tuning voltage input signal to provide a current dump output signal corresponding to the channel strength of the P-channel and N-channel transistors. Trip-point compensation circuit provides a net ring current signal as the current control signal to the ring oscillator.
    Type: Grant
    Filed: January 17, 1991
    Date of Patent: October 29, 1991
    Assignee: National Semiconductor Corporation
    Inventor: Richard R. Rasmussen
  • Patent number: 5038118
    Abstract: A circuit configuration of an integratable and controllable ring oscillator for generating a clock signal includes first and second stages being connected between supply terminals and having input and output terminals. The output terminal of the first stage is connected to the input terminal of the second stage. An inverter is connected between the output terminal of the second stage and the input terminal of the first stage. The input terminal of the second stage supplies a clock signal. Each of the stages includes first and second transistors having load paths connected between the supply terminals in a series circuit with a connecting point between the transistors. The second transistor has a gate terminal connected to the input terminal. The first transistor determines the frequency of the clock signal, is controllable in accordance with a control variable and acts as a current source. A capacitor has one terminal connected to the connecting point and another terminal connected to a fixed potential.
    Type: Grant
    Filed: September 5, 1990
    Date of Patent: August 6, 1991
    Assignee: Siemens Aktiengesellschaft
    Inventor: Ulrich Langenkamp
  • Patent number: 5021751
    Abstract: A quadrature oscillator network for simultaneously producing a sine wave and a cosine wave. The oscillator includes an integrating circuit and a time delay circuit, each of which is preferably constructed, in part, with an operational amplifier. In one example, a first output is developed from the integrating circuit and transmitted to the time delay circuit. The time delay circuit receives the first output from the integrating circuit and generates a second output. The integrating circuit and the time delay circuit are interconnected with a feedback branch which is employed to transmit the second output of the time delay circuit to an input of the integrating circuit. In the preferred form of operation, the first output is sinusoidal in form and the second output is cosinusoidal in form.
    Type: Grant
    Filed: February 27, 1990
    Date of Patent: June 4, 1991
    Inventor: Mitchell Rose
  • Patent number: 4973920
    Abstract: A controllable quadrature oscillator, having a pair of oscillator outputs for supplying a pair of phase quadrature oscillator signals, is a cascade circuit of two quadrature sections incorporated in a regenerative loop each contributing a 90.degree. phase shift in the regenerative state of the loop. In order to increase the frequency control range of such a controllable quadrature oscillator and to enable realization by integrated circuit technology, each quadrature section is formed of two stages in cascade arranged in a signal path between an input terminal and an output terminal for the quadrature section. One of the stages includes a first amplifier having a low-pass characteristic and the other of the stages includes a second amplifier having a low-pass characteristic and having a feedback path. The gain of at least one of the two amplifiers is controllable for controlling the frequency of the pair of phase quadrature oscillator signals.
    Type: Grant
    Filed: November 16, 1989
    Date of Patent: November 27, 1990
    Assignee: U.S. Philips Corporation
    Inventor: Wolfdietrich G. Kasperkovitz
  • Patent number: 4947141
    Abstract: A sinewave oscillator and a quadrature phase shift network fabricated as an integrated circuit for a Barber radio receiver comprising, in order that the network and oscillator be simply adjustable to provide an accurate 90.degree. shift and a sinewave of accurate frequency and high spectral purity, a first capacitance means (C1, C2; C4, C5) coupled to the input of a gyrator (G1; G2) comprising first and second amplifiers (10, 12; 22, 24) connected in feedback configuration with a capacitance (C3; C6) connected to the output of the first amplifier. The oscillator network may be adjusted by current control of transconductance of the amplifiers, and the amplifiers include input signal limiting means to limit the input signal to a linear operating region. An output load resistance (R) may be simulated using a further amplifier connected in feedback configuration.
    Type: Grant
    Filed: May 17, 1989
    Date of Patent: August 7, 1990
    Assignee: Flessey Overseas Limited
    Inventors: Simon Atkinson, Francis Carr
  • Patent number: 4914401
    Abstract: The invention can be related to the technical field of implementation and control of electricity controllable active fibers.In accordance with the invention filters are controlled and implemented with the aid of a differential gain stage. Said stage includes pairs of like amplification components (Q.sub.I11 and Q.sub.I21, Q.sub.I12 and Q.sub.I22, Q.sub.I13 and Q.sub.I23), and groups of series-connected diode components as well as at least one current generator (Q1, Q2, Q3). The forward voltage drop of the diode components has the same current responsiveness as the base-emitter voltage of the amplification components. A filter of the first order includes a differential gain stage with a capacitive component (C) connected across the output of said stage or to its amplification components. A filter of the second order can include two differential gain stages, each with its capacitive component (C1, C2) in circuit.
    Type: Grant
    Filed: May 17, 1988
    Date of Patent: April 3, 1990
    Assignee: Telefonaktiebolaget L M Ericsson
    Inventor: Heinz B. Mader
  • Patent number: 4901037
    Abstract: An amplitude stabilized oscillator which includes an amplifier having an input, an output, and a control terminal. The amplifier has a frequency determining feedback circuit connected between its output and input terminals, and has a control voltage produced by two opposite current sources applied to its control terminal. An amplitude detector detects the oscillator output amplitude during at most one half of each oscillation period and produces an amplitude stabilizing signal which is applied to one of the two current sources.
    Type: Grant
    Filed: September 1, 1988
    Date of Patent: February 13, 1990
    Assignee: U.S. Philips Corporation
    Inventor: Ernst Feller
  • Patent number: 4893095
    Abstract: An oscillator, for example, a ring oscillator, comprises an oscillator stage which includes a current source in series with a parallel connection of a switching element (a transistor) and a capacitance. A delay circuit is connected between the junction point of the current source and the parallel connection and the input of the switching element. The oscillation frequency is determined to a suitable approximation by the capacitance and by the ratio of the magnitude of the switching threshold of the switching element and the current to be supplied by the current source. A frequency stabilization means for the oscillator adjusts the current to be delivered by the current source by means of a resistor so that the ratio of this current and the switching threshold is proportional to the value of the resistor. The constant resistance value of the resistor is then a factor which determines the oscillation frequency.
    Type: Grant
    Filed: July 28, 1988
    Date of Patent: January 9, 1990
    Assignee: U.S. Philips Corporation
    Inventor: Werner F. Thommen
  • Patent number: 4891609
    Abstract: A ring oscillator circuit comprises a plurality of inverter states (301, 302, 303) connected in a series loop. Each stage has a voltage input (315, 315', 315") with an associated input capacitance and input threshold voltage, and a current output (316, 316', 316"). An active output circuit regulates the output currents so as to regulate the frequency of oscillation. A single reference circuit (307) can be used by more than one stage. The output circuit can vary the output currents to compensate for variable supply voltages. The oscillator can be used as part of a bias generator in an integrated circuit.
    Type: Grant
    Filed: December 2, 1988
    Date of Patent: January 2, 1990
    Assignee: U.S. Philips Corporation
    Inventor: Edward S. Eilley
  • Patent number: 4879530
    Abstract: A phase shifter VCO has at least first and last fundamental circuits each including an amplifier adding circuit, a control input connected to all of the other control inputs for a tuning potential varying an amplification operative ratio between the first input and the output to the second input and the output of the adding circuit, a reference input for a reference potential, symmetrical first and second non-inverting and inverting circuit input pairs, a symmetrical non-inverting and inverting circuit output pair, and a symmetrical timing element having an input connected to the first circuit input and having an output forming the first input of the adding circuit. The first non-inverting input of the first fundamental circuit is connected to the non-inverting output of the last fundamental circuit, and the first inverting input of the first fundamental circuit is connected to the inverting output of the last fundamental circuit.
    Type: Grant
    Filed: November 14, 1988
    Date of Patent: November 7, 1989
    Assignee: Siemens Aktiengesellschaft
    Inventors: Wilhelm Wilhelm, Winfried Birth