Showing papers on "Voltage-controlled oscillator published in 1982"

Self-calibrated clock and timing signal generator for MOS/VLSI circuitry

Abstract: A self-calibrated clock and timing signal generator provides reliable and continuous arbitrary digital waveforms of preselectable edge resolution. The generator comprises a multistage means to produce a time delayed signal of preselectable edge resolution and having a plurality of outputs or taps between a plurality of series connected delay stages comprising the multistage means. The delay per stage is substantially identical so that the selection of any one of the outputs is representative of a predetermined amount of delay provided to an input signal to the multistage means. Calibrating means is integrally included to develop a control signal which is coupled to each of the stages of the multistage means to continuously maintain the predetermined amount of delay per stage. In the embodiment described, the calibrating means takes the form of an automatic frequency control (AFC) loop wherein the frequency of a voltage controlled oscillator (VCO) is regulated to be equal to that of a reference frequency. The VCO comprises a plurality of series connected delay stages. The control voltage is applied to each stage to control the period of frequency of the VCO. The control voltage developed to adjust the VCO frequency is also employed to regulate the delay of the stages comprising the multistage means. The stages of the delay line are identical in construction to the stages of the VCO.

Temperature compensation of an oscillator by fractional cycle synthesis

Abstract: A method for temperature compensating the output of an oscillator circuit and apparatus for performing the method. This method employs fractional cycle synthesis to maintain the output frequency of a voltage-controlled oscillator at a desired value, the reference frequency of the circuit being derived from a crystal oscillator. To calibrate the circuit, the crystal oscillator is cycled in temperature. The frequency output of the crystal oscillator is accurately counted while a digital signal representing temperature is generated by an analog-to-digital converter from a temperature sensor. A signal representing the relationship between crystal frequency and temperature is stored in a memory and is available during actual operation of the oscillator for temperature compensation. During oscillator operation the output of the memory, as it relates to an instantaneous ambient temperature of the crystal, is appropriately treated and then injected into a phase locked loop containing the voltage-controlled oscillator, thereby affecting the input voltage to the oscillator to control the frequency output thereof. The stabilized frequency output of the VCO is offset from the crystal reference frequency and it is this offset that is shifted by very small amounts to provide the desired compensation of the oscillator output.

Optical phase modulation in an injection locked AlGaAs semiconductor laser

Abstract: Optical phase modulation by injecting coherent CW light into a directly frequency modulated semiconductor laser is reported. Phase modulation was obtained at up to 800 MHz modulation frequency without distortion for a 1.6 GHz full locking bandwidth. A static phase shift of π took place with a 0.48 mA bias current change in the injection locked laser. Experimental and theoretical results showed that the product of the normalised phase deviation by the frequency deviation and the cutoff modulation frequency is constant.

Fast lock PLL having out of lock detector control of loop filter and divider

Abstract: A phase-locked loop comprises a reference source that produces a signal at a fixed frequency that is applied to a phase detector. That signal is compared in the phase detector with a divided quotient signal that is proportional to the output of a voltage-controlled oscillator. Comparison of the phase difference between the two signals creates an output voltage that is taken to an adaptive filter. The adaptive filter is controlled by an external logic circuit that selects a narrow bandwidth when phase lock is detected and a wider bandwidth when the absence of phase lock is detected. The divisor of the divider in the loop is also changed in response to a signal based on the phase difference. The output of the adaptive filter is taken to a summer which adds a modulating signal to form a combined controlled voltage for the VCO.

Wideband modulation sensitivity compensated voltage controlled oscillator

Abstract: A control oscillator voltage, the modulation sensitivity compensation broadband compensates automatically and continuously over a wide bandwidth modulation sensitivity changes resulting from changes in the center frequency of the oscillations. The oscillator comprises an array direction (30) coupled to the input of a network oscillator (20) for controlling the central frequency. A modulation network (50) is also coupled to the network input oscillator (20) via a compensation network (40). The compensation network (40) continuously varies the coupling between the modulation network (50) and the network oscillator (20) in response to control signals applied to the input (32) of the steering network (30) so as to compensate the variations in modulation sensitivity.

Frequency synchronization and phase locking of CO2 lasers

Abstract: Employing the principle of a phase‐locked loop (PLL) we have synchronized the frequency and phase of two CO2 lasers. The laser acting as voltage controlled oscillator is tuned both by electro‐optic and piezoelectric means. A cooled photodiode serves as the phase detector. The main loop parameters, natural frequency ωn and damping factor ζ, have been measured. The small phase jitter in the error signal obtained will allow application of such an optical PLL in homodyne receivers at 10 μm.

System for linearizing sweep of voltage controlled oscillator

Abstract: Non-linearities in the sweep output of a voltage controlled oscillator are automatically linearized by a scheme that compensates for changes in slope of the variation in frequency with time during a high accuracy calibration mode, prior to placing the VCO into real time operation. During the calibration mode the sweep rate of the VCO is slowed down as the operational frequency range of interest is divided into a prescribed number of subfrequency segments or windows. During each window, an input control code, obtained from a random access memory (RAM) and representative of the intended slope of the VCO frequency sweep (for that window of interest), is applied to a digital-to-analog converter (DAC) whose output is integrated and applied to the voltage control input of the VCO. Since the output of the DAC is integrated, the frequency variation control signal to be applied to the VCO is a slope change control signal, which is incrementally adjusted, as required, during successive sweeps of the VCO, so as to produce a precompensated control voltage that will cause the rate of change of the VCO frequency output to track an intended ramp (linear with time) or other chosen frequency variation output.

Data tracking clock recovery system using digitally controlled oscillator

Abstract: A clock recovery system including a VCO responsive to a voltage signal for generating a clock signal. A phase detector includes a register and a PROM, the register counting the clock signal to derive the output clock signal. The PROM is responsive to input data and the count in the register to detect and store information concerning relative phase relationships. A counter contains a count from which the control voltage for the VCO is derived. The PROM is operable to alter the count in the counter, thereby performing frequency adjustments, and to alter the count in the register to perform phase adjustments. Also, a converter, operable by the phase detector, may also derive a voltage signal for damping purposes.

Voltage controlled oscillator

Abstract: A wide range voltage controlled oscillator arrangement has a VCO in which an n-stage switchable capacitor network provides a set of n overlapping frequency ranges and a variable capacitance responsive to a control signal (e.g. from a feedback loop filter) adjusts the VCO frequency within each range. A window detector detects when the control signal exceeds upper or lower limits and increments/decrements an up/down counter in association with a clock. The counter contents are applied to a decoder to provide 1-out-of-n range selection signals to effect switching of the VCO capacitor network. Clock is inhibited when the control signal is within the prescribed limits.

Apparatus for generating a common output signal as a function of any of a plurality of diverse input signals

Abstract: A circuit for generating a common signal as a function of either of two reference signals comprises a pair of phase-locked loops which share an oscillator. Each phase-locked loop generates a control signal as a function of one of the reference signals. One or the other of the control signals is coupled to the oscillator which generates the common signal. A comparator compares the two control signals and generates a signal indicative of their difference. While the control signal generated by the first phase-locked loop is coupled to the oscillator, the difference signal is applied to the second phase-locked loop where it controls the generation of the second control signal to minimize the difference between the two control signals. While the control signal generated by the second phase-locked loop is coupled to the oscillator, the second phase-locked loop is nonresponsive to the difference signal. Thus when a switch of reference signals occurs even if they are of different phase and even if that phase is slowly time-varying, the circuit can lock to the new reference signal at a phase dictated by the phase difference between the two references at the instant of the switch without causing the oscillator output to undergo significant frequency or phase changes.

Horizontal scanning frequency multiplying circuit

Abstract: A horizontal scanning frequency multiplying circuit comprises a flip-flop supplied with a horizontal synchronizing signal having a horizontal scanning frequency f H , which is set by this horizontal synchronizing signal, a phase-locked-loop, and a counter. The phase-locked-loop comprises a voltage controlled oscillator for producing a signal having a frequency Nf H (N is an integer over 1) which is N times the horizontal scanning frequency f H , a frequency divider for frequency-dividing an output signal frequency of the voltage controlled oscillator, and a phase comparator supplied with one output signal of the flip-flop and an output signal of the frequency divider, for comparing phases of these signals and applying an output error signal to the voltage controlled oscillator to control the oscillation frequency of the voltage controlled oscillator. The counter is supplied with the other output signal of said flip-flop which is reset by this output signal, and supplied with the output signal of the voltage controlled oscillator within the phase-locked-loop as a clock signal, and produces a counted output every time the clock signal is counted for a predetermined counting time T, to supply this counted output to the flip-flop in order to reset the flip-flop. The voltage controlled oscillator within the phase-locked-loop produces a signal having a frequency Nf H .

PLL for regenerating a synchronizing signal from magnetic storage

Abstract: A phase-locked loop circuit, which obtains a signal synchronized with a phase of an input signal, including a synchronizing portion, and a data portion having a voltage controlled oscillator, a frequency phase comparator, a phase comparator, and a control circuit. The frequency phase comparator detects the phase difference and the frequency difference between the input signal and the output of the voltage controlled oscillator and the phase comparator detects the phase difference between the input signal and the output of the voltage controlled oscillator. The control circuit controls the voltage controlled oscillator, at least during a portion of the synchronizing signal portion, in accordance with the output of the frequency phase comparator, and, during the data signal portion, in accordance with the output of the phase comparator.

Monolithic Voltage Controlled Oscillator for X and Ku-Bands

Abstract: A GaAs Voltage Controlled Oscillator Circuit that tunes from 1115 to 1439 GHz and 160 to 1874 GHz has been designed and fabricated The 11 mm x 12 mm chip includes two varactors, a 300 µm FET, bypass capacitors, tuning inductors and isolation resistors Wideband circuit design techniques will be described Varactor and circuit effects causing the non-continuous bandwidth will be discussed showing the capability of continuous 11 to 18 GHz tuning using a single GaAs chip

Baseband demodulator for FM signals

Abstract: A demodulator of the type employed in a "zero-IF" system uses a local oscillator for providing guadrature output signals at the center frequency of an FM signal to be demodulated. The demodulator has first and second mixers for separately mixing the FM signal with the quadrature signals to provide a first and second output signal each in quadrature at the outputs of said mixers. These signals are low pass filtered. The demodulator includes third and fourth mixers with each mixer receiving at an input one of the low pass signals. At another input the mixers receive third and fourth signals. The third and fourth signals are derived from mixing a variable controlled oscillator (VCO) signal with the local oscillator guadrature signals. The outputs of the third and fourth mixers are applied to the inputs of a difference amplifiers, the output of which controls the frequency of the VCO in an automatic frequency control mode (AFC) to cause the output of the difference amplifier to provide demodulated signal. A switching means operates to alternate the third and fourth signals as applied to the input of the third and fourth means as well as the output as applied to the difference amplifier to cause an additional amplifier coupled to the outputs of the mixers to provide a DC control signal used for automatic gain control.

Variable frequency U. H. F. local oscillator for a television receiver

Abstract: A tunable oscillator develops a signal having a frequency variable over a range of frequencies in response to a control signal. A frequency determining resonant circuit includes two voltage-variable capacitance diodes in an arrangement for adjusting at least one endpoint of the frequency range. As a result, the relationship between the magnitude of the control signal and the frequency of the oscillator signal can be adjusted while avoiding mechanically adjustable reactive elements. The disclosed arrangement is suitably employed with resonant circuits other than those in oscillators.

Switching power supply

Abstract: A switching power supply has a power switching transistor furnishing a series of shaped pulses to output means for providing an output voltage, has control means including a voltage controlled oscillator responsive to the output voltage for providing control pulses whose frequency is representative of the output voltage level, and has saturable transformer means coupling the control pulses to the switching transistor for driving the transistor to regulate the output voltage within a selected range. First winding means on the saturable transformer drive the transformer to saturation with each control pulse and other winding means forward bias the switching transistor to conduct while the transformer is being driven to saturation and thereafter reverse bias the transistor to rapidly turn it off as the transformer recovers from saturation. The power supply includes means for varying transistor switching frequency and pulse width for regulating output voltage.

Voltage-controlled oscillator

Abstract: PURPOSE:To decrease the change in the sensitivity of modulation due to band switching and the band switching width, by constituting selectively a capacitive element and an inductance element to a tuning circuit of an oscillator in response to the band switching CONSTITUTION:A microstrip line resonator 1 is coupled between a transistor negative resistance generating circuit 3 and a varactor diode circuit 2, and a band switching circuit 4A to change over the frequency is constituted at the side of the varactor diode of this resonator 1 A PIN diode 22 is conductive by a DC bias voltage from a DC bias terminal 33 when a selecting switch 24 is turned on at first in performing the band changeover, a capacitor 21 is given to the tuning circuit of the oscillator to change over the frequency Further, a PIN diode 28 is conductive by the DC bias voltage, a band changeover inductor 35 is given to the tuning circuit through a high frequency conducting capacitor 34, allowing to change over the other frequency

MOS Phase lock loop synchronization circuit

Abstract: A metal oxide semiconductor (MOS) phase lock loop data synchronization circuit, for use in conjuction with an integrated circuit disk controller device, comprising a temperature, process, and voltage compensated MOS voltage controlled oscillator (VCO), a three-bit counter, and a phase detector circuit. The phase detector circuit compares a decoded clock signal output from the VCO with incoming data from a disk device to detect phase differences between the frequency of the VCO and the actual frequency of the incoming data. The phase detector produces voltage signals in response to any such phase differences, which are coupled to the VCO and alter the frequency output of the VCO to match the frequency of the incoming data. The counter provides a system read-clock, which is fully synchronized with the incoming data, to an integrated circuit disk controller device which further processes the data.

Phase difference measurement system

Abstract: A system and technique is disclosed which enables the production of in-phase and quadrature phase signals useful for deriving phase difference measurements. In an in-phase and quadrature phase difference measurement system, the phase shifter employed must receive an input signal and produce an output signal which is 90° out of phase and equal in amplitude to the input signal over the full frequency range of the input signal. This is accomplished by using a phase locked loop which locks onto the input signal and uses the output of a voltage controlled oscillator located in the loop to derive the sine and cosine of the input signal. The resulting sine and cosine outputs are then 90° out of phase and form in-phase and quadrature phase signals which have equal amplitudes. These two signals maintain lock over the frequency range of the input signal and may be used as inputs in the phase difference measurement system.

Wideband phase locked loop tracking oscillator for radio altimeter

Abstract: A wideband phase locked loop oscillator (PLLO) for tracking the frequency of an altitude signal in an FM/CW type radio altimeter. The phase locked loop oscillator conventionally includes a voltage controlled oscillator (VCO), a phase comparator for comparing the phase of the altitude signal to be tracked with the phase of the VCO output and an error signal amplifier for applying the output of the phase comparator as control voltage to the VCO. The frequency range of the PLLO is extended by changing the natural frequency of the VCO in steps spanning the useful frequency range of the altitude signal. Selection of the proper value of VCO natural frequency is effected through microprocessor directed digital control.

Monolithic Voltage Controlled Oscillator for X- and Ku-Bands

Abstract: A GaAs voltage controlled oscillator circuit that tones from 11.15 to 14.39 GHz and 16 to 18.74 GHz has been designed and fabricated. The 1.1 mm x 1.2-mm chip includes two varactors, a 300-µm FET, bypass capacitors, tuning inductors, and isolation resistors. Wide-band circuit design techniques will be described. Varactor and circuit effects causing the noncontinuous bandwidth will be discussed showing the capability of continuous 11 to 18 GHz tuning using a single GaAs chip.

FM Transceiver frequency synthesizer

Abstract: A frequency synthesizer used for a frequency modulation (FM) transceiver which uses negative feedback to make the modulation characteristics linear and stable over a wide frequency range. The negative feedback is comprised of a frequency mixer, which mixes the outputs of a local oscillator and a voltage controlled oscillator, and a frequency divider and demodulator, which act on the output of the frequency mixer and supply the demodulated output signal to an adder, where it is added in reverse phase to the modulating signal.

A simple three-phase variable-fraquency oscillator

Abstract: The paper describes a hybrid, three-phase oscillator with variable frequency and voltage, and reversible phase sequence. The oscillator digitally generates three 120° phase shifted square waves, and mixes them in balanced modulators with a fixed frequency sine wave. The signals from the modulators are token through active filters resulting in constant amplitude, low distortion three-phase sine wave outputs. The magnitude of the output, voltage is controlled by varying the amplitude of the fixed frequency sine wave source. It has good frequency and phase stability.

Voltage-controlled oscillator having three or more varactor diodes

Abstract: In a voltage-controlled oscillator having an LC resonant circuit including a varactor circuit so that resonant frequency is controlled by a D.C. bias or control voltage applied to the varactor circuit, three or more varactors are connected in series in one embodiment so that a high-frequency voltage applied to the varactor circuit is divided into a plurality. The varactors may be connected in the same direction or opposite direction. In another embodiment, a plurality of series circuits of varactors are connected in parallel to provide the varactor circuit, where each series circuit comprises two or more varactors. A series-parallel connection of a plurality of varactors may be arranged in a matrix. In order to reduce undesirable stray capacitance, some or all varactors are attached to a printed circuit board so that they are normal to the plane of the printed circuit board. In one embodiment an auxiliary printed circuit board is employed so that some varactors are spaced from a main circuit board. The voltage-controlled oscillator of the invention shows high carrier-to-noise ratio throughout a wide frequency range.

Sound signal and impulse noise detector for television receivers

Abstract: In a television signal processing apparatus, a phase-locked loop (PLL) is provided for detecting the audio information from the television signal and for providing a defect control signal which, when applied to compensation circuitry, reduces impulse noise effects in the video information. The PLL includes a phase detector, a lowpass filter (LPF) and a voltage controlled oscillator (VCO). The phase detector has a first input coupled to be responsive to the frequency modulated sound signal produced by the tuner, a second input coupled to be responsive to the output of the VCO and an output coupled to the LPF. The LPF provides a phase control signal to the VCO and provides the detected audio information. A signal mixer serving as a synchronous detector has first and second inputs coupled to the first and second inputs, respectively, of the phase detector and has an output for providing the defect control signal indicative of the amplitude variations of the frequency modulated sound carrier.

Linear sweep frequency modulator for FM/CW radio altimeter

Abstract: A linear sweep frequency modulator for a varactor tuned transistor microwave oscillator used in an FM/CW radio altimeter where the oscillator-frequency v. varactor bias characteristic is non-linear. A linear triangular wave is converted by means of a function generator to the non-linear wave required for varactor bias to cause linear frequency modulation of the oscillator. Linearity of modulation is tested by measuring variations in the period of a calibration signal derived from a delay line. Variations in the period of the calibration signal are measured by determining the difference between the average and the instantaneous calibration period and sampling the difference during each cycle of the triangular wave, once during the upswing thereof when the oscillator is at low frequency and once during the down swing thereof when the oscillator is at high frequency and separately integrating the up swing and down swing samples. By applying both results of integration to the function generator it thereby has its biases controlling the low frequency and the high frequency operation of the oscillator separately adjusted.

Phase locked loop with improved lock-in

Abstract: The circuit determines whether an incoming frequency is within the normal "lock-in" range of a phase locked loop VCO or not, and whether it is higher or lower than the VCO frequency. If not within normal range, the beats are rectified and gated to provide a DC control voltage of the proper value and polarity for locking the oscillator on the incoming frequency. Rectification may be half or full wave as needed, and the circuit may include filter bandwidth control as well. This circuit is suitable for signals of any waveform, quadrature signals, and AM stereophonic signals.

Simplified frequency scheme for coherent transponders

Abstract: A coherent transponder having a transmitter and a receiver operating at different frequencies with each including a numerically controlled oscillator for controlling the frequency thereof through a single-sideband modulator and various outputs from a phase-locked loop the frequencies of the numerically controlled oscillators and the phase-locked loop being referenced to a single crystal controlled oscillator.

Saw oscillator with digital compensation for temperature related frequency changes

Abstract: The inherent temperature instability of surface acoustic wave (SAW) clock oscillators is improved by the use of a thermometer oscillator circuit that senses temperature changes in the SAW substrate. The thermometer oscillator is used in combination with a calibrated programmable read only memory and a logic circuit and provides frequency corrections to the clock oscillator. The basic device is an oscillator clock circuit using a SAW substrate having a delay path orientation with good temperature stability. A second oscillator, the thermometer oscillator circuit, and the electronic compensation scheme are added in order to produce minimum temperature coefficient of delay over all temperatures in the range of interest. The thermometer oscillator delay path utilizes a high temperature coefficient of delay orientation of the same SAW substrate and at an appropriate angle to the clock oscillator delay path orientation. Its frequency of oscillation is used as a highly accurate thermometer in order to control a correction signal applied to a variable phase shifter in the clock oscillator loop.

Electronic phase detector having an output which is proportional to the phase difference between two data signals

Abstract: A phase detecting circuit for use in a phase-locked loop is provided with a pair of bistable circuits such as type D flip-flops. One of the circuits is clocked by a controlled output signal from a voltage controlled oscillator, and reset by an input reference signal. The other of the bistable circuits is clocked by an inverted input reference signal and reset by an inverted output signal from the voltage controlled oscillator. The Q and NOT Q outputs of these bistable circuits are fed to a voltage divider and shifted in magnitude by a fixed amount such that the phase error detection signal is a constant zero when the input reference signal and output signals are in phase.