Abstract: The invention relates to a biased electronic circuit in which a voltage-controlled component has a characteristic with a non-linear portion and a substantially linear portion. The circuit is biased by a voltage being applied to one terminal of the component thereby shifting the operation of the component to the linear portion.

Abstract: A voltage controlled oscillator provides a fixed amplitude output at an adjustable frequency. The voltage controlled oscillator includes a first transistor including an emitter, a base, and a collector. A first capacitor is connected between the emitter and the base of the first transistor. An inductance simulating device generates a controllable impedance and includes second and third transistors each with a base, an emitter, and a collector. The second and third transistors are connected between the base and the collector of the first transistor. The controllable impedance includes an inductive reactance component related to a quiescent bias current flowing through the third transistor. A current source connected to the third transistor generates the quiescent bias current to vary the inductive reactance component. The inductive reactance component and the first capacitor vary the adjustable frequency of oscillation.

Abstract: A battery-powered, magnetic-pen oscillator includes a circuit having a first transistor arranged in a common emitter configuration. A feedback loop includes a transformer and the transistor that produce a loop phase shift of zero degrees and a loop gain of one to cause oscillation, and additionally creates the magnetic field emitted by the pen. A second transistor provides current mirror biasing for the first transistor and determines the amount of current flowing through the first transistor.

Abstract: A stabilized oscillation circuit includes a bias circuit which controllably biases a bipolar-transistor-driven crystal oscillator circuit. The bipolar-transistor-driven crystal oscillator circuit is a modified version of a conventional transistor-driven oscillator, such as a Hartley, Pierce or Colpitts-type circuit. The bias circuit includes a first current providing a reference current through a Schottky diode and a pair of bipolar transistors. The bipolar-transistor-driven crystal oscillator circuit includes an input and an output, where the input of the bipolar-transistor-driven crystal oscillator circuit is coupled to the bias circuit. The bipolar-transistor-driven crystal oscillator circuit includes a second current through a second bipolar transistor. The second current tracks the reference current so that the output of the bipolar-transistor-driven oscillator circuit is substantially constant over variations in ambient temperature.

Abstract: An embodiment of the present invention is a single-chip GPS receiver front-end comprising a radio frequency amplifier, a voltage-controlled oscillator operating at a first local oscillator frequency, a divide by seven and one-half counter for deriving a second local oscillator frequency from the first and a first and second mixer. The local oscillator frequency is mid-way between two carrier frequencies of interest that may be received by the radio frequency amplifier and the first mixer produces a first intermediate frequency. The second local oscillator frequency is then beat with the first intermediate frequency in the second mixer to produce a second intermediate frequency. A dual-conversion super heterodyne configuration is therefore employed in which the first and second local oscillator frequencies are derived from a single oscillator and the first local oscillator frequency is seven and one-half times the second local oscillator frequency.

Abstract: A variable reluctance transducer system incorporating digital control of parallel resonant circuits including two inductive sensors L1 and L2 on each side of a flat diaphram. The dual variable reluctance elements provide dual frequency signals for digital calculation to obtain a quotient of the frequencies, thereby substantially eliminating the resonant frequencies as a variable in the accuracy of the device. Manipulation of the produced quotient by a micro-controller 10 employing digital calibration tables stored in a programmable read only memory 14 allows calibration reponsive to a temperature sensor 16, thereby substantially eliminating temperature induced errors in the system, further increasing accuracy.

Abstract: The invention relates to a temperature-stable transistorised tuned-circuit oscillator. Provided for the purpose of temperature stabilisation of the tuned-circuit voltage is a transistor T2, which is thermally coupled to the tuned-circuit coil L and controls a current source Q in the circuit of the oscillator L, C1, T1, in such a way that temperature-induced variations of the data of the tuned-circuit coil L are compensated.

Abstract: A voltage controlled oscillator is disclosed in a "ring" configuration using two BJTs. The design uses an active feedback topology which eliminates the need for a tank circuit for oscillation to occur. The design also provides for the mixing function to be performed by one of the BJTs.

Abstract: A voltage controlled oscillator (VCO) circuit (10) for operating at low supply voltages has been provided. The VCO circuit includes an oscillation stage which utilizes a negative resistance technique for oscillation and includes a first inductor (38) for allowing the oscillation stage to operate at low supply voltages. The VCO circuit also includes an output stage which includes a second inductor (52) and a first capacitor (51) for allowing the output resistance of the VCO circuit to be adjusted for maximum output drive capability.

Abstract: A crystal oscillator circuit has a sleep mode of operation that reduces power consumption while maintaining oscillation to provide for a fast transition to a normal mode of operation.

Abstract: A voltage controlled oscillator (VCO) circuit having a cascoded output stage has been provided. The VCO circuit includes an oscillation stage which utilizes a negative resistance technique for oscillation, and an output stage that is coupled in cascode with the oscillation stage thereby minimizing the power dissipation and allowing the output resistance of the VCO circuit to be adjusted for maximum drive capability.

Abstract: A differential amplifier of the cascode type comprises a differential stage which includes a first (T.sub.1) and a second (T.sub.2) transistor whose collectors are connected to an active load constituted by the respective collector-emitter paths of a third (T.sub.3) and a fourth (T.sub.4) transistor in series with a first and a second resistor, respectively. One end of each resistor is connected to a supply voltage terminal. The third and the fourth transistor have their bases connected to a reference voltage terminal. A first capacitor (C.sub.1) is coupled between the collector-emitter paths of the third and of the first transistor, and a second capacitor (C.sub.2) is arranged between the collector-emitter paths of the fourth and of the second transistor. A third (R'.sub.1) and a fourth (R'.sub.2) resistor are connected between the supply voltage terminal (V.sub.cc) and the collector-emitter path of the first transistor and of the second transistor, respectively.

Abstract: The present invention resides in a push-push voltage controlled oscillator (VCO) utilizing parallel LC resonant tank circuits for improved phase noise characteristics. The push-push VCO of the present invention includes two voltage controlled oscillators connected in parallel and in phase opposition, with each oscillator including a transistor connected in series with the parallel LC resonant tank circuit. The oscillators operate at the same resonant frequency f.sub.0, but are 180 degrees out of phase. Therefore, the fundamental and odd harmonics of the resonant frequency f.sub.0 cancel each other out and the even harmonics add together to produce an output signal at twice the resonant frequency f.sub.0.

Abstract: A frequency modulation oscillator circuit includes an oscillator stage having two emitter-coupled transistor pairs, each being fed from at least one controllable current source, and at least one trigger stage for triggering the controllable current sources for the two transistor pairs.

Abstract: An embodiment of the present invention is a voltage controlled oscillator (VCO) comprised of a differential pair of transistors that have respective positive feedback paths with phase-lead networks cross-coupled. Each positive feedback path on each side has two different phase-lead branches. The two phase-lead branches have the same phase differences on each side of the differential pair, in order to maintain a symmetry that improves common-mode noise rejection on a voltage control differential input. Current-steering is used to control the mixture of currents that arrive at the bases of the differential transistor pair from the respective two different phase-lead branches, and thereby changing the frequency of the VCO.

Abstract: A voltage controlled oscillator comprises a resonant circuit having at least a coil and a first variable capacitance diode, and resonating within predetermined variable frequency ranges; and an active circuit having an input, an output, and an active element connected between the input and the output, the input being connected to the resonant circuit in order to receive a resonant output therefrom. A variable capacitance ratio circuit, having a second variable capacitance diode and at least one capacitor, is connected in a positive feedback manner, between the input and the output of said active circuit means in order to oscillate the active element of the active circuit at a resonant frequency of the resonant circuit, between the input and the output of the active circuit.

Abstract: An improved crystal oscillator and output circuit is disclosed. The oscillator has a normal operating mode and a low-power mode. In the low-power mode, a reduced current which is sufficient to maintain oscillation is supplied to the oscillator and the output circuit is disabled. The oscillator can subsequently be returned to normal mode and the output circuit enabled. Since the oscillator is never shut completely off, the time required to resume normal mode oscillations is reduced.

Abstract: An oscillation circuit has a differential amplifier including a constant current source formed by a resistor and a transistor whose emitter is grounded through the resistor, and a feedback circuit through which an output of the differential amplifier is positively fed back to an input of the same differential amplifier. The oscillation circuit further includes a band-gap regulator for producing a band-gap voltage proportional to a thermal voltage of transistors forming the band-gap regulator whose emitter areas are different with each other, and an operational amplifier for DC-amplifying the band-gap voltage and applying the amplified band-gap voltage to the base of the transistor forming the constant current source. The oscillation circuit is capable of performing a stable oscillation against a wide range of temperature changes.

Abstract: An oscillator includes at least one oscillator transistor having collector, emitter and base leads, a controllable current source connected between the emitter lead of the at least one oscillator transistor and a supply potential, and a frequency-determining element, such as an oscillating circuit, connected at least to the base or collector lead of the at least one oscillator transistor. A method for controlling the amplitude of the output signal of the oscillator includes supplying a direct voltage variation at the emitter lead of the at least one oscillator transistor resulting from a change in amplitude of a signal applied to the base lead of the at least one oscillator transistor as a controlled variable for the current of the controllable current source. The oscillator may also include a control amplifier. The emitter lead of the at least one oscillator transistor is connected to one input of the control amplifier and the other input of the control amplifier is connected to a reference potential.

Abstract: A voltage control oscillator (400) includes a tank circuit (402) wihch includes a control input (118). The VCO (400) further includes a feedback section (106) which includes a transistor (108). The feedback circuit (106) further includes a feedback compensation circuit 420 which compensates the feedback ratio of the feedback circuit (106) over changes in frequency of operation in order to provide for a substantially constant open loop gain. The improved VCO (400) provides for fairly constant current drain over changes in frequency as well as lower power output variations and flatter Side Band Noise Ratio response over frequency.

Abstract: A voltage controlled oscillator circuit including an oscillator circuit having first and second terminals to which an external inductance is connected. A frequency control voltage (V.sub.F) is applied through a bias circuit to the second terminal for varying the center frequency. The oscillator circuit may have an AGC circuit or a modulation circuit connected to it. An output amplifier is connected with the first terminal and has an adjustable output impedance for matching the input impedance of a load circuit.

Abstract: An inductive proximity switch with adjustable switching hysteresis includes a presence indicator having an oscillator with an oscillating circuit and oscillator amplifier, a switch amplifier connected downstream of the presence indicator, an electronic switch controllable by the presence indicator through the switch amplifer, and a demodulator assigned to the oscillator. The presence indicator has an electronic circuit with a temperature dependency compensating for a temperature dependency of the switching point of the inductive proximity switch. The temperature dependency of the switching point of the inductive proximity switch is dictated by the temperature dependency of the quality of the oscillating circuit.

Abstract: An integrable variable-frequency oscillator circuit with a feedback amplifier configuration includes first and second input terminals. A frequency-determining feedback element is connected between the input terminals. First and second amplifier stages have inputs connected to the first input terminal and outputs supplying output signals generated by the amplifier stages. The second amplifier stage has a variable gain. A first phase-shifting component is connected to the output of the second amplifier stage for receiving the output signal of the second amplifier stage. A third amplifier stage is connected downstream of the first phase-shifting component for generating an output signal. The output of the first amplifier stage is connected downstream of the phase-shifting component for adding the output signal of the first amplifier stage to the output signal of the second amplifier stage.

Abstract: A voltage controlled oscillator circuit has been provided that allows for varying the center frequency of oscillation through an applied voltage signal (V.sub.F). Further, the center frequency of oscillation can be fine tuned around the center frequency via a modulation signal (S.sub.M). The voltage controlled oscillator circuit utilizes a negative resistance technique for oscillation and includes an output amplifier whose output resistance can be adjusted to match the input impedance of another circuit for maximum drive capability.

Abstract: A voltage-controlled oscillator (VCO) mounted on a laminated printed circuit board which has a surface layer, a plurality of intermediate layers, and a back layer. Various component parts of the VCO are arranged on the surface layer. One of the intermediate layers which underlies the surface layer constitutes a ground potential layer and is removed at locations thereof corresponding to the area where the parts of the VCO are positioned.

Abstract: An RF oscillator is disclosed that can be tuned to operate over a wide range of frequencies while maintaining advantageous bias conditions. The oscillator includes circuitry that adjusts an oscillator bias signal in response to changes in oscillator frequency and/or ambient temperature, and does so without resort to using the same signal for both bias and frequency control. By so doing to control parameters such as phase noise, output power and compression angle, both the frequency range and temperature range of an oscillator can be extended, while simultaneously improving the oscillator's performance.

Abstract: An oscillator circuit is tunable by a tuning circuit which includes a spiral inductor disposed on a ferrite substrate. The oscillator circuit is tuned or modulated by varying a current through the spiral inductor.

Abstract: An improved frequency modulation apparatus (100) is provided comprising a generator (102), a biasing voltage line (116), and an interface circuit (110). The generator (102) is utilized to generate a carrier signal. A control line input (104) on the generator (102) adjusts the frequency of the carrier signal. The biasing voltage line (116) provides DC power in order to DC bias the generator (102). The interface circuit (110) couples an information signal (114) to the biasing voltage line (116) for altering the biasing of the generator (102) in response to the information signal (114). The alteration of the biasing of the generator (102) results in the carrier signal being frequency modulated by the information signal (114).

Abstract: An oscillator includes first and second transistors and a parallel resonant circuit. The resonant circuit has first and second ends. The first end of the resonant circuit is connected to a base of the first transistor and a collector of the second transistor. The second end of the resonant circuit is connected to a base of the second transistor and a collector of the first transistor. A voltage dropping device is connected between the first end of the resonant circuit and a power supply for providing a voltage drop to expose the first and second transistors to driving voltages lower than a voltage of the power supply.

Abstract: A clock recovery circuit includes a tuned-tank circuit for receiving RZ data signals, a comparator for converting an analog clock signal produced by the tuned-tank circuit to a digital clock signal, and a positive feedback of the digital clock signal to the tuned-tank circuit for self-regenerating the clock signal.

Abstract: A PLL synthesizer includes a voltage-controlled oscillator generating an output signal having a frequency based on a first signal supplied thereto, a PLL control circuit which generates a second signal based on the output signal and a set frequency, a lowpass filter having an input terminal and an output terminal, for filtering the second signal supplied through the input terminal to thereby generate the first signal supplied to the voltage-controlled oscillator through the output terminal, and a switch circuit which is coupled between the input and output terminals of the lowpass filter and which supplies the second signal directly to the voltage-controlled oscillator during a predetermined time when the set frequency is changed.

Abstract: The invention relates to a temperature-stable inductive proximity switch having a transistorized resonant circuit oscillator. The feeding into the emitter-to-collector circuit of the resonant circuit transistor T1 of a balancing current, which depends on the individually determined temperature of the resonant circuit transistor T1 and the individually determined temperature of the resonant circuit coil, ensures that the proximity switch is temperature-stable with respect to its switching distance for every adjusted basic current.

Abstract: A diode tuned resonant circuit (42) with an inductor (L1) a first variable reactance diode (VAR1) connected in parallel with the inductor (L1), and a second variable reactance diode (VAR2) connected in series with the parallel combination of the inductor (L1) and first diode (VAR1) is used in an oscillator circuit. The resonant frequency of the circuit may be adjusted over a relatively broad frequency range while maintaining a relatively constant Q-factor by applying a biasing voltage to the first and second diodes (VAR1, VAR2).

Abstract: A voltage-controlled variable oscillator, in particular for phase-lock loops, comprising a differential stage formed by a pair of transistors and collectors whereof define the output terminals between which an external resonating circuit is connected, a voltage generator which is connected between the two output terminals and is suitable for generating a voltage which is proportional to the terminal voltage which exists across the resonating circuit, and a pair of capacitors connected between a respective output terminal and the voltage source.

Abstract: A sensor according to this invention comprises an oscillation circuit including an LC resonant circuit, wherein a detection signal is prohibited upon arrival of an external radio wave.

Abstract: A stable sampling clock signal is supplied from a VCO circuit which is able to operate in a synchronous manner with an external sync signal that does not posses good phase stability while also providing an enlarged range of variable frequency output. The VCO circuit of this invention comprises an oscillation output circuit, such as NAND or NOR circuit, having one input connected to receive an external sync signal and having its output for providing the desired oscillation or sampling clock frequency. A control voltage circuit is connected to the other input of the oscillation output circuit and to the output of the oscillation output circuit.

Abstract: A balanced oscillator circuit having first and second outputs includes a transistor circuit, having internal parasitic capacitors, for providing first and second output signals at the first and second outputs of the balanced oscillator circuit. An inductor circuit is coupled between the first and second outputs such that the inductor circuit and the internal parasitic capacitors determine the frequency of oscillation of the first and second output signals. The capacitance of the internal parasitic capacitors can be varied by an external voltage applied to the transistor circuit.

Abstract: In an oscillator (1) comprising a parallel resonant circuit (4), which for fine-tuning the oscillator includes a variable capacitance which is variable in dependence upon a fine-tuning control signal and is constituted by the capacitance occurring in the collector circuit of a transistor. This transistor is a separate transistor (12) whose collector is capacitively coupled to the parallel resonant circuit and which is arranged in common base configuration for alternating current, while its operating point is chosen to be in its saturation range, the fine-tuning control signal being applied to the base-emitter path of this transistor and the transistor base-collector junction, which is in its pass region, being driven further into conduction by this signal within its control range on the one hand, and being driven from its pass region into its cut-off region on the other hand.

Abstract: A varactor diode tuned voltage controlled oscillator which simultaneously optimizes several techniques to minimize AM to FM conversion in the LC resonant circuit to provide an RF signal having minimum phase noise is described. A high gain current limiting RF amplifier is coupled to a high Q, high capacitance, low impedance LC resonant circuit by an impedance transformation network to provide a high tank circulating power having minimum RF voltage fluctuations. The RF voltage across the varactor tuning diodes is further reduced by connecting two varactor diodes in series, back-to-back, or by connecting a fixed capacitance in series with the parallel connected varactor diodes.

Abstract: A single pin oscillator which consists of first and second transistors (17, 18) whose collectors are connected, via respective collector resistances (19, 20), to the positive pole of a DC source U.sub.V and whose emitters are connected to the negative pole thereof via respective emitter resistances (21, 22). The collector of each transistor is connected to the base of the other transistor. A quartz crystal (12) or a series resonant circuit is connected to the emitter of one transistor (17) and parallel to the corresponding emitter resistance (21). A driver circuit (23) is provided for an oscillator voltage which can be coupled out to an external low-ohmic, highly capacitive load connected to the emitter of the other transistor (18) and parallel to the corresponding emitter resistance (22).

Abstract: The electronically tuned power oscillator (ETPO) of the present invention provides a method and apparatus that drives a narrow-band (high Q) transducer over a relatively broad band of frequencies. A pseudo-random sequence generator dynamically switches a bank of capacitors varying the resonant frequency of the power oscillator. A node on the power oscillator provides the clock for the pseudo-random sequence generator thereby providing a synchronized frequency change on every time varying cycle.

Abstract: An oscillation circuit of a proximity switch includes a parallel LC resonance circuit (L, C), an oscillation transistor (Tr6) controlled by an output voltage from the resonance circuit for switching a constant current and a feedback circuit (Tr2, Tr3) for feeding back a current flowing through the oscillation transistor to the resonance circuit. In the circuit, there is further disposed a feedback current increase circuit including a second transistor (Tr7) controlled by an output voltage from the resonance circuit and a resistor (R) connected in series to the second transistor. The resonance circuit is supplied via the feedback circuit with a feedback current obtained by adding a current flowing through the feedback current increase circuit and a current passing through the oscillation transistor, thereby developing a large change in the amplitude of the oscillation.

Abstract: An oscillator including a first frequency control network having a series coupled inductance and sensor capacitor, a pair of cascaded capacitors, and an emitter follower amplifier coupled thereto. The emitter follower amplifier drives a current limiter and a feedback path, whereby the current through the emitter follower amplifier is divided between the current limiter and the feedback path in a manner establishing an oscillatory potential in the oscillator, while keeping the transistor of the emitter follower amplifier substantially out of its saturation state.

Abstract: An improved control circuit for maintaining constant amplitude of the sinusoidal output signal of an oscillator circuit by synchronously demodulating the signal using a push-pull transistor pair operating in saturation to generate a control signal for comparison with a reference voltage in a direct coupled negative feedback loop to the oscillator. The configuration of the feedback loop provides effectively instantaneous control response to eliminate low frequency modulation propagated internally in the oscillator due to noise generation in circuit components.

Abstract: A resonant switching converter including a first series resonant circuit including a first inductor and a first capacitor connected in series with a voltage source, a second series resonant circuit including a second inductor and the first capacitor, a switch connected in series with said second inductor and responsive to the current in the first inductor for enabling a discharge path through the load for the charge stored by the first capacitor. A first control circuit responsive to the voltage on the first capacitor may also be provided for operating the switch at a controlled voltage to facilitate line and load regulation. A second control circuit responsive to the output voltage may be included to provide line and load regulation. The switch is only closed after the resonant capacitor has charged to its peak value or beyond.

Abstract: A varactor diode tuned voltage controlled oscillator which simultaneously optimizes several techniques to minimize AM to FM conversion in the LC resonant circuit to provide an RF signal having minimum phase noise is described. A high gain current limiting RF amplifier is coupled to a high Q, high capacitance, low impedance LC resonant circuit by an impedance transformation network to provide a high tank circulating power having minimum RF voltage fluctuations. The RF voltage across the varactor tuning diodes is further reduced by connecting two varactor diodes in series, back-to-back, or by connecting a fixed capacitance in series with the parallel connected varactor diodes.

Abstract: A high-frequency power oscillator is built around a power amplifier utilizing semiconductors in a complementary or quasi-complementary stage which operate in a switching mode of operation. The output of the amplifier supplies high-frequency oscillations to a load impedance through an output filter composed of a series-resonant circuit and a parallel-resonant circuit. A feedback driving voltage is obtained from the output filter in a manner providing a first portion of the driving voltage from a voltage present in the parallel-resonant circuit for voltage feedback and a second portion of the driving voltage obtained by current inverse feedback from the current in the series-resonant circuit. These two components of the driving voltage are combined in an addition circuit and supplied to an input of the power amplifier through a pulse modification stage.

Abstract: A push-pull high voltage oscillator power supply circuit includes a parallel resonant LC circuit made up of a capacitor in parallel with the primary of an output transformer. The output power level of the oscillator is controlled or adjusted by gating a drive circuit of the oscillator in accordance with an appropriate timing scheme so as to control the power delivered to the load over a long time period. The drive circuit is switched on and off so as to control the transformer primary voltage by omitting a number of drive pulses, determined by the desired output pulse level, so that the oscillator self-oscillates and rings out with a decreasing amplitude of the self-oscillats and rings out with a decreasing amplitude of the self-oscillations, but never reaches a complete cut-off of the oscillations before the drive circuit is gated on to refresh the supply of energy to the oscillator.

Abstract: A timing recovery apparatus for a burst mode communication receiver. The apparatus provides for optimum sampling and digitizing of received data at a plurality of data rates. In particular, a VCO is phase-locked to a local frequency reference prior to data being received. A reference timing preamble transmitted prior to the data is filtered and fed to the VCO causing it to injection lock such that the VCO becomes phase aligned with the preamble. The VCO is then permitted to "free run" during data transmission and continues to operate at substantially the same frequency. A synchronous divider and multiplexer, responsive to the VCO, allows selection of sampling clocks for the plurality of data rates. The divider is forced to a known state during VCO injection locking, to assure that the sampling clocks have maintained the proper phase for optimal sampling at the corresponding data rate. Further, means is provided to monitor the frequency of the VCO.

Abstract: A self contained circuit to enable a tank type (coil/capacitor) voltage controlled oscillator to start up and free run from a known state. The circuit allows the oscillator to be stopped to within two periods by invoking its only input logic signal and also restarted with no adverse effects on its free running operation. It includes three current mirrors, one which sets the current for the other two mirrors and of the final two, one actively sets a bias on a coil (stops oscillation) while the other makes up for the lack of coil bias by providing an equivalent amount current influx to the oscillator in the free running condition.