Abstract: An oscillator having a tank circuit, an amplifier circuit and a switching circuit. The switching circuit switches the oscillator between a normal power consumption mode and a lower power consumption mode. The amplifier circuit includes an emitter biased transistor. The switching circuit switches between power consumption modes by switching between two selected voltages at the base of the transistor. When in the lower power consumption mode, the oscillator has sufficient current to sustain oscillation but insufficient current to meet the phase noise requirements for good fidelity and high data rates.

Abstract: A controllable LC oscillator circuit has a resonant circuit including an inductance and a capacitance disposed in parallel. The oscillator is driven by an amplifier and the inductance is produced using coupled coils. The effective inductance of the coupled coils can be set by changing a gain of the amplifier, and a magnitude of the coupling factor of the coupled coils defines a magnitude of an adjustable frequency band of the oscillator.

Abstract: A voltage-controlled oscillator (10), which is comprised of two subcircuits (10a, 10b). Each subcircuit (10a, 10b) has a pair of differentially connected transistors (Q1,Q2 and Q3,Q4). The first subcircuit (10a) is an LC oscillation subcircuit, in which each transistor (Q1, Q2) has a capacitive transformer (C11,C12 and C21,C22) in its feedback loop. The second subcircuit (10b) is a current-controlled variable-capacitance subcircuit, whose feedback loop has a gain that determines the effective capacitance of the subcircuit (10b). When the subcircuits (10a, 10b) are combined, the feedback loops on each side of the differential pairs (Q1,Q2 and Q3,Q4) share the capacitive transformer (C11,C12 and C21,C22). The result is that the effective capacitance determines the oscillation frequency for the oscillator (10).

Abstract: An integrated circuit (shown below dashed line A--A) for a voltage controlled oscillator comprises a first transistor (T.sub.1) having its collector coupled to a first port (Port 1) via a filter comprising a capacitor (C.sub.f) and an inductor (L.sub.f) and its emitter coupled to the emitter of a second transistor (T.sub.2) whose collector is coupled to a second port (Port 2). The collector of the first transistor is also coupled via a capacitive divider (C.sub.1, C.sub.2) to the base of the second transistor. The base of the first transistor is AC decoupled (C.sub.3). The emitters of the first and second transistors are fed by a current source (I.sub.1). A capacitor (C.sub.s) connects the base of the second transistor to the first port. The first and second ports are for connection to an external resonator (L.sub.1, D.sub.1, C.sub.p, L.sub.p) (shown above dashed line A--A) where C.sub.p and L.sub.

Abstract: Briefly, in accordance with one embodiment of the invention, a circuit includes: a voltage tunable inductive-capacitive (LC) oscillator, a charge pump, and a phase detector. The oscillator, detector, and charge pump are coupled together to form a PLL.

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.

Abstract: A method and apparatus for synthesizing high-frequency signals is disclosed that overcomes integration problem associated with prior implementations while meeting demanding phase noise and other impurity requirements. In one embodiment, a phase-locked loop (PLL) frequency synthesizer is disclosed having a voltage controlled oscillator (VCO) with a variable capacitance that includes a discretely variable capacitance in conjunction with a continuously variable capacitance. The discretely variable capacitance may provide coarse tuning adjustment of the variable capacitance, and the continuously variable capacitance may provide a fine tuning adjustment of the variable capacitance. In a more general terms, a frequency synthesizer is disclosed having a first variable and a second capacitance circuits and frequency control circuitry to coarsely tune the output frequency by adjusting the first control signal and to finely tune the output frequency by adjusting the second control signal.

Abstract: A local oscillation circuit in a frequency converter circuit includes a resonant circuit, and a differential amplifier circuit connected to the resonant circuit. The differential amplifier circuit includes two transistors constituting a differential stage. One end of the resonant circuit is connected to the base of one transistor via a capacitive element, and to the collector of the other transistor via a capacitive element. The other end of the resonant circuit is connected to only the base of the other transistor via a capacitive element. Accordingly, an unbalanced oscillate operation is performed in the local oscillation circuit, leading to reduction of the phase noise caused by decrease in an oscillation output due to the trap phenomenon, and an improvement in reception quality.

Abstract: An oscillator includes four identical cells each producing a phase shift of 90 degrees. The output signal from one cell is applied to the input of the next cell, and with the cells looping back to themselves. Each cell includes a current amplifier and a parallel inductance-capacitance resonant circuit configured such that the output current from one cell is a fraction of the capacitive current of the parallel resonant circuit. This causes the 90.degree. phase shift between the input and output currents of each cell.

Abstract: A variable high frequency voltage controlled oscillator (VCO) which is fully integrated. By controlling, with a control voltage, the collector current flowing through one transistor of the integrated oscillator circuit, the diffusion capacitance (also known as base-charging capacitance) of that transistor is varied. Since, in conjunction with an inductance, this capacitance to a large degree determines the frequency of oscillation of the integrated circuit, a fully integrated VCO is made possible.

Abstract: An integrated circuit (IC) comprising an oscillator (OSC) has a first amplifier (AMP.sub.1) and a second amplifier (AMP.sub.2). The first and the second amplifier (AMP.sub.1, AMP.sub.2) each have a non-inverting input, an inverting input, and an output. The output of the first amplifier (AMP.sub.1) is connected to the non-inverting input of the first amplifier (AMP.sub.1) and also to the non-inverting input of the second amplifier (AMP.sub.2). The output of the second amplifier (AMP.sub.2) is connected to the inverting input of the first amplifier (AMP.sub.1) and also to the inverting input of the second amplifier (AMP.sub.2). The first amplifier (AMP.sub.1) is loaded with a capacitor (C) connected between the output of the first amplifier (AMP.sub.1) and an external power supply terminal (1). The second amplifier (AMP.sub.2) is loaded with a further capacitor (C.sub.F) connected between the output of the second amplifier (AMP.sub.2) and the external power supply terminal (1).

Abstract: A voltage controlled oscillation circuit includes a resonance circuit and an oscillation circuit. The oscillation circuit includes a capacitor, a variable capacitance diode, and a resonator composed of a strip line one end of which is grounded. The oscillation circuit includes an oscillation transistor, bias resistors, and, a Colpitts capacitor, a harmonic bypass capacitor, and a chip capacitor, one end of which is connected in series with a resistor and the other end of which is grounded. A node between the bias resistor and the chip capacitor connects the resonator composed of a strip line provided within the resonance circuit via a connection line, whereby the emitter of the oscillation transistor provided within the resonance circuit is grounded via the bias resistor and the resonator. In addition, a parallel resonance circuit is composed of the resonator and the chip capacitor.

Abstract: An oscillator is formed by a resonator (RES) coupled to an amplifier (AMP) via a coupling path (COP). In order to counter unwanted oscillations due to parasitic resonances in the coupling path (COP), the coupling path (COP) includes a series resistance (RS). This allows better performance in terms of noise for countering unwanted oscillations, despite the fact that the series resistance is in itself a source of noise. An even better noise-performance is obtained if the coupling path (COP) also includes a series capacitance. Such a series capacitance will also effectively widen a frequency range over which the oscillator can be tuned.

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.

Abstract: An oscillator comprises an active device with a phase shift of less than 180 degrees. A first delay line has first and second ends. The first end of the first delay line is coupled to an active port of the active device. A ring mode trap filter is coupled to the second end of the first delay line. A second delay line has first and second ends. The first end of the second delay line is coupled to the ring mode trap filter. The second end of the second delay line is coupled to a resonance means. The total delay of the first and second delay lines allows the resonance means to oscillate at its natural frequency in spite of the less-than-180-degree phase shift of the active device.

Abstract: A fully integratable voltage controlled oscillator (VCO) circuit includes a tuned circuit having a spiral inductance connected in parallel with a varactor controlled by a control voltage. Damping of the tuned circuit is counteracted by a cross-coupled NIC (Negative Impedance Converter). The cross-coupling of the NIC, which transforms a negative resistance into the tuned circuit, is provided by AC coupling of two outputs. Bipolar transistors are provided only for current source transistors, while in contrast CMOS transistors are provided in a current switch. The VCO can be used, for example, in DECT units.

Abstract: A voltage controlled oscillator for upconverter/downconverter in a digital radio communication system has an improved phase noise characteristic and includes: a resonance unit wherein a variable capacitance component is parallel-connected to a series resonance circuit, the variable capacitance component having a capacitance inversely proportional to the level of a control voltage in a preset range and the series resonance circuit having a series resonance point corresponding to the level of a mode voltage, and an oscillating unit for oscillating at a frequency corresponding to a parallel resonance point determined by the resonance unit.

Abstract: A voltage controlled oscillator (1) comprising a voltage controllable variable resonant circuit (2) having a control input (Vctrl), a positive feedback input (6) and a controllable variable frequency output (7). The voltage controlled oscillator (1) also has an amplifier (3) having an amplifier input coupled to the controllable variable frequency output (7) and an oscillator output (Out). A positive feedback path (4) couples the amplifier (3) to the a positive feedback input (6) and a frequency dependent negative feedback path (5) provides increased negative feedback to the amplifier (3) as the Radio Frequency increases.

Abstract: A voltage control oscillator capable of obtaining the desired output voltage by lowering the higher order harmonic level, is provided. Further, in the voltage control oscillator, a resonance circuit achieves the resonance by switching two different resonance frequencies. Moreover, inductors of a matching circuit are selectively used to change the inductance by turning on/turning off a diode of an impedance regulation circuit according to the respectively switched frequencies. Furthermore, the synthesized impedance with a matching capacitor is changed to achieve the matching with each of two frequencies.

Abstract: A quenchable VCO that is adapted to be used in switched band synthesizer applications. The VCO may be formed from a heterojunction bipolar transistor (HBT) in a common collector configuration. A quenching circuit which includes a p-i-n diode, is electrically coupled in series with the collector of the HBT. The p-i-n diode is adapted to be monolithically integrated with the HBT. Since the p-i-n diode is electrically connected to the collector of the HBT, as opposed to the base and emitter terminals of the HBT, which forms the main oscillator feedback loop, the Q-factor of the p-i-n diode will have relatively less loading on the phase noise of the HBT oscillator. Moreover, since the p-i-n diode is isolated from the base-emitter junction, the configuration will result in reduced frequency pulling and generation of spurious oscillation and transient effects due to the switching of the p-i-n diode quenched circuit.

Abstract: A stabilized oscillator circuit is provided with a differential amplifier type oscillator circuit for generating an oscillation signal, and a differential amplifier type buffer output circuit for amplifying and outputting the oscillation signal. The stabilized oscillator is also provided with a frequency variation stabilizing circuit. This circuit controls the amount of current of the constant current source I2 of the buffer output circuit, in accordance with fluctuations of the power supply voltage applied to the oscillator circuit. Accordingly, the collector-base capacitance of the transistors of the buffer output circuit is controlled, and the oscillation frequency variations are suppressed in spite of fluctuations of the power supply voltage.

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.

Abstract: The invention provides an improved variable capacitance circuit which is substantially linearly controlled using voltage or current control. The circuit comprises two emitter connector transistors and a constant current source or drain forming a current steering circuit. A fixed capacitor is connected to the emitters of the transistors forming a port into the circuit. AC current into the port flows through the fixed capacitor and is fed back through the transistors in a proportion depending on the voltage at their bases. The effective capacitance of the circuit is varied using this variable AC feedback arrangement. Other embodiments use current control to vary the circuit capacitance by varying the effective constant current source level.

Abstract: A Voltage Controlled Oscillator (VCO) mitigates the effects of package parasitics by providing positive feedback connections, to sustain a desired oscillation, external to the IC package, thereby mitigating the effect of the bond wires and internal parasitics to allow the oscillation to be controlled by the desired external components. The VCO includes an electronic circuit with gain that is at least part of an integrated circuit (IC) and a package for the IC. A passive resonant circuit may be provided external to the IC package. The positive feedback of the electronic circuit is provided through at least one additional lead of the package, such that the connection is external to the package.

Abstract: A Colpitts-type voltage-controlled oscillator includes a transistor having a collector which is connected to a power terminal through a stripline. A capacitor is connected between the collector and the emitter thereof. A diode is connected to the capacitor and an inductor is connected to a point between the capacitor and diode. Another capacitor is connected between the base and the emitter of the transistor. An inductive reactance is formed by a stripline which is connected between the base of the transistor and the ground, two capacitors for DC blocking, and a variable-capacitance diode. Bypass capacitors are connected between the collector of the transistor and the ground. A resistor is connected between the emitter of the transistor and the ground. Two other resistors are provided for dividing a power voltage at the power terminal and for supplying a base voltage to the transistor. Turning the diode on and off allows the oscillating frequency of the voltage-controlled oscillator to vary by a large amount.

Abstract: An oscillator circuit (100) provides improved noise immunity by utilizing a differential common base configuration. The oscillator includes a differential transistor pair (102, 104) having common bases (110) coupled through an AC ground (108) and emitters coupled through a differential common mode point (120). First and second resonant tank circuits are each referenced to the differential common mode point (120) for generating a differential output (OUT, OUTX).

Abstract: An oscillator having two oscillation circuits with widely different frequencies with a common passive switched output circuit. Each oscillator circuit includes a transmission line inductive impedance between the oscillator output and ground. The inductive impedances are selected to be open at the operating frequency of the associated oscillator circuit and a short or a low impedance at the frequency of the other oscillator circuit. Each inductive impedance forms a portion of an impedance matching pad for the other oscillator circuit.

Abstract: An electronic oscillator of the Colpitts type with an amplifying element and a tank circuit. The tank circuit includes a parallel tuned resonant circuit, a series tuned resonant circuit and a switching circuit that selectively connects one of the resonant circuits to the tank circuit. The oscillator operates at a first frequency in the parallel tuned mode and a second frequency that is substantially twice the first frequency in the series tuned mode.

Abstract: A voltage controlled oscillator for wide tuning range of frequency with less phase noise has a bipolar transistor provided with a positive feedback circuit between a base and an emitter of the transistor, an impedance matching circuit coupled with a collector of the transistor and an output terminal, a resistor coupled between the base of the transistor and a control source which provides control voltage for adjusting oscillation frequency of the oscillator. The base of the transistor shows capacitive negative impedance, and an inductive element is coupled with the base of the transistor for oscillation. The emitter of the transistor is grounded for D.C. voltage through an inductor or a transmission line, or coupled with a control voltage.

Abstract: A transformerless power oscillator for driving a high intensity electrodeless light bulb. The driver uses a silicon carbide static induction transistor (SIT) operating as a power oscillator powered by an unregulated power supply potential generated by a full wave rectifier bridge connected to an AC power line. A CW output signal is generated at S-band and is coupled to the excitation coil of an electrodeless lamp by means of a matching network.

Abstract: A circuitry arrangement for a resonant circuit that may be completely monolithically integrated and electrically tuned has a differential amplifier stage with two transistors T.sub.1,T.sub.1 ' fed by a constant current source I.sub.0 that are differentially loaded at their collectors by a voltage-dependent capacity and inductively loaded in relation to the circuit ground by a pair of emitter followers T.sub.2,T.sub.2 ' with electrically adjustable impedance that act upon the base. To implement the electrically adjustable impedances, transistors with associated resistances are provided (for example a pair of emitter followers T.sub.3,T.sub.3 ' with base pre-resistances R.sub.1,R.sub.1 ') which may be adjusted by control currents (for example I.sub.1 I.sub.1 ') . The voltage-dependant capacity is implemented by transistors T.sub.4,T.sub.4 ' whose short-circuited emitters and collectors are connected so that the circuit node thus obtained is applied to the circuit ground through a voltage source U.sub.1.

Abstract: The object of this invention is an oscillation circuit that increases the Q of the parallel resonance circuit and increases the C/N (carrier-to-noise) ratio. The oscillation circuit contains two feedback capacitors connected between the base and emitter and between the emitter and collector of a transistor. Two inductors are also connected in series between the base and the collector of the transistor. One end of a resistor is connected to the emitter of the transistor and the other end is connected between the two inductors. The feedback capacitors and inductors constitute a parallel resonance circuit that may be tuned to create an equipotential across the ends of the resistor so that no current flows through it thus increasing both Q and the C/N ratio.

Abstract: A voltage controlled oscillator (1) comprising a voltage controllable variable resonant circuit (2) having a control input (Vctrl), a positive feedback input (6) and a controllable variable frequency output (7). There is an amplifier (3) having an amplifier input coupled to the controllable variable frequency output (7). A positive feedback path (4) couples the amplifier (3) to the positive feedback input (6) and there is selectable load (5) in parallel with the positive feedback path (4) for selectively reducing the SideBand Noise Ratio.

Abstract: A high-performance voltage controlled oscillator without use of variable capacitance (varicap) diodes which is easy in fabrication in an semiconductor IC form. The voltage controlled oscillator includes:a differential amplifier having a differential pair of transistors (Q.sub.1, Q.sub.2); an LC resonance circuit having a coil (L.sub.0) and a capacitor (C.sub.0); a phase shift circuit for receiving a differential output of the differential amplifier via a buffer of transistors (Q.sub.3, Q.sub.4) and for providing its output for the differential amplifier in a positive feedback mode; and a current control circuit for variably controlling an operating current (Ie) of the phase shift circuit according to a controlled voltage applied from a circuit other than those in the voltage controlled oscillator.

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).

Abstract: An oscillator operable in the gigaHertz range includes a transistor having an emitter coupled to a tank circuit and an additional feedback path coupling the tank circuit back to the base of the transistor. The inductive elements of the tank circuit are in printed foil form as is a transmission line that provides the additional feedback path. This arrangement improves the phase noise characteristics of the oscillator while extending its operating frequency range.

Abstract: An oscillator usable for a TDMA type wireless mobile communication device in which an average current at the communication terminal is decreased. The oscillator has a switching circuit or a timing circuit which controls an operating current of an amplifying element 8 for oscillation and reduces an average current in a TDMA operation without changing a voltage applied to a passive element constituting the oscillator. In particular, before initiating oscillation, elements in a negative impedance circuit are charged with a current of a value which does not cause the oscillation of the oscillator, and at the time of initiating the oscillation, a current capable of oscillating the oscillator is supplied to the negative impedance circuit.

Abstract: A voltage controlled oscillator has a cross-coupled negative resistance cell formed as an integrated circuit connected to off-chip components of a high-Q resonant tank circuit. To counteract spurious oscillations brought about by package parasitics caused by the interconnection of the chip to the external components, the cell is provided with a degeneration impedance. Typically, a pure inductor is used if all the elements of the tank circuit are off-chip. In a case where the tank circuit includes an on-chip fixed capacitor, the degeneration impedance may take the form of a capacitor.

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.

Abstract: A Pierce oscillator has been modified to replace the large capacitor with an amplifier element in order to make it more compact. A first amplifier element has a control terminal and a main current path extending between first and second output terminals. A network feeds back the signal at the first output terminal of the first amplifier to the control terminal of the first amplifier element and includes a series-arranged piezoelectric oscillation element. The oscillator also includes a reactive circuit element such as a resonant LC circuit or inductor (herein called an output dipole) coupled to the first output terminal of the first amplifier element and a DC current defining element coupled to the second output terminal of the first amplifier element.

Abstract: A low-noise oscillator circuit with an amplifier element for negative feedback, specifically a transistor. In addition to a positive feedback of the oscillator transistor, provision is made for a negative-feedback loop with a pass band of 0 (thus DC coupling) to 1/4 to 1/100 of the oscillation frequency of the oscillator, in order to regulate out fluctuations of the current of the amplifier element.

Abstract: A transmitter VCO (204) includes nodes for receiving a band selector voltage for altering the base-emitter capactance of a transistor to enable the VCO to act as an oscillator in the appropriate band, and for altering the resonator capacitance to change the resonant frequency of the oscillator. The method and apparatus enables oscillation in different frequency bands for dual mode communication devices.

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.

Abstract: A voltage controlled oscillator (10) operable on two widely separated frequency bands of 800 MHz and 1.9 GHz, for example. The two operable frequency modes are controlled by changing base bias voltages on at least two transistors with commonly connected emitters. A base circuit of each transistor is connected to an independent resonator and tuning element and shares a common feedback reactance. By increasing a base bias voltage of first transistor relative the a second transistor, an associated first base circuit is turned on and allowed to oscillate at a first frequency while a second base circuit is turned off preventing oscillation at a second frequency. Correspondingly, by decreasing the base bias voltage the first base circuit is turned off and the second base circuit is turned on. The transistors share a common collector connection and output providing either one of the two frequencies.

Abstract: An oscillation circuit comprises a surface acoustic wave resonance device of the single port type, an active circuit portion with which the surface acoustic wave resonance device is connected so that a signal feedback from the active circuit portion to the surface acoustic wave resonance device is carried out, an inductive element connected substantially in parallel with the surface acoustic wave resonance device, and a damping portion connected with one or both of the inductive element and the surface acoustic wave resonance device for suppressing parasitic oscillations caused by coaction between the inductive element and stray capacitance accompanying the surface acoustic wave resonance device.

Abstract: An active circuit includes an amplifying transistor (102), a voltage reference (208), and an active bias circuit. The active bias circuit controls the operating point of the amplifying transistor, and includes a bias transistor (224) which is controlled by the voltage reference and the collector current of the amplifying transistor. As the temperature of the amplifying transistor changes, the tendency of the collector current to change is counter-acted by the bias transistor and the voltage reference.

Abstract: An integrated circuit voltage-controlled oscillator includes an amplifier, a low Q LC resonator coupled to the amplifier, and a voltage-controlled variable delay element connected to delay feedback between an output and an input of the amplifier.

Abstract: A variable-path-length voltage-controlled oscillator circuit is provided. The oscillator circuit has a ring oscillator formed from a series of voltage-controlled inverter stages. The path length (i.e., the number of inverter stages) in the ring is selected based on path length configuration data stored in memory. The selected path length determines the nominal or center frequency of operation of the ring oscillator. The output frequency of the oscillator circuit is voltage-tuned about this center frequency by varying the delay of each inverter stage in the ring oscillator path. Various types of voltage-controlled inverter stages may be used, including current-starved inverter stages, variable-capacitive-load inverter stages, and differential-delay inverter stages. The voltage-controlled oscillator circuit may be used in a phase-locked loop on a programmable logic device for frequency synthesis or to eliminate clock skew.

Abstract: An integrated oscillation circuit used for frequency conversion circuit in which UHF frequency conversion and VHF frequency conversion are selectively energized to use a common IF amplifier. The integrated oscillation circuit is used for a local oscillation circuit. The integrated oscillation circuit including a connection terminal connected to an external resonance circuit and an input line of a mode switching signal which is set at a different level in response to an operation mode, an oscillation element, a bias terminal of which is connected to the connection terminal, a detection circuit detecting the level of the mode switching signal applied to the bias terminal of the oscillation element, and a switching circuit turning on and off a power source for driving the oscillation element in response to the level detected at the detection circuit.

Abstract: A voltage controlled oscillator has an active circuit, a resonant circuit coupled to the input node of the active circuit and an adjustable impedance circuit coupled to an output node of the active circuit. The impedance of the adjustable impedance circuit may be altered to tune the oscillation frequency of the oscillator. In one embodiment, the adjustable impedance circuit includes a varactor diode in series with a capacitor and means for varying the voltage across the varactor diode. An isolation circuit is coupled to an output node of the active circuit. In one embodiment, the isolation circuit is connected to a different output node than the adjustable impedance circuit is connected to.