Showing papers on "Relaxation oscillator published in 1984"

Ring oscillator substrate bias generator with precharge voltage feedback control

Abstract: A generator circuit for producing a negative bias voltage on a substrate for a semiconductor device employs a multistage on-chip oscillator driving individul charge pump circuits for each stage. The oscillator may produce a frequency related to the value of the negative bias, using a feedback circuit. Each of the charge pump circuits includes a capacitor and an MOS diode coupled to the substrate and another diode coupled to the ground terminal of the supply.

Electronic proximity sensor

Abstract: An electronic sensor of the contactless type has a free-running oscillator with internal positive feedback supplemented by an external negative feedback including a capacitive path whose impedance is normally high but is lowered in the presence of an object to be detected, thereby reducing the output signal of the oscillator from a normal amplitude above a predetermined level to a diminished amplitude below that level. The negative feedback is provided through an IGFET, e.g. of n-channel depletion type, with the aid of a capacitor bridging its source and gate electrodes to form with the external capacitance a voltage divider for the output signal of the oscillator.

Theoretical and experimental study of the operation of ovonic switches in the relaxation oscillation mode. I. The charging characteristic during the off state

Abstract: A simple theory of the charging cycle is presented for ovonic switches operating in the relaxation oscillation mode. The theory takes into account the variation of the OFF‐state resistance with bias voltage. An analytical expression for the period of oscillation as a function of circuit components and device parameters is obtained showing that a nonlinear increase of the period of oscillation exists with increasing series resistance. The presented theory is in good agreement with experimental results.

Voltage-controlled variable-frequency pulse oscillator

Abstract: The voltage-controlled variable-frequency pulse oscillator in accordance with the present invention comprises an integrating capacitor (50), a variable current source (52) for generating charging current for said integrating capacitor in response to the controlling voltage, a fixed current source (54) for discharging said capacitor, a switching circuit (56) for controlling the discharge of said capacitor, a comparator (58) for outputting a discrimination signal by comparing the voltage of the capacitor and a reference voltage, a dn a multivibrator (60) for receiving the discrimination signal from the comparator and for outputting a pulse signal with a frequency corresponding to the controlling voltage from the variable current source. The multivibrator comprises an R-S flip-flop (64,66) for receiving the discrimination signal output by the comparator at its set side OR-NOR gates, and receiving and for inverting the output of the set side gate which is delayed by a prescribed time to the reset side OR-NOR gate. The R-S flip-flop is constructed to permit the oscillation output with a prescribed frequency to betaken out from the reset side OR-NOR gates, and the oscillation output of the R-S flip-flop controls the drive of the switching circuit. Therefore, the multivibrator starts oscillation on its own within a prescribed width when the capacitor voltage grows very large at the time of turning the power supply on or at the time of generation of an excessively large current where the output of the comparator continues, to stay at a constant value. Furthermore, the current value of the fixed current source is set at more than twice the maximum current value of the variable current source. Because of this, the large voltage of the capacitor decreases gradually with ups and downs, and the comparator inverts after a certain time, the multivibrator discontinues the self oscillation, and the ordinary operation of the device takes place.

Narrow deviation voltage controlled crystal oscillator

Abstract: A narrow band, voltage controlled crystal oscillator having a linear frequency versus tuning voltage response The oscillator uses a composite resonator in a novel circuit configuration with a resulting improvement in oscillator output signal frequency stability

Metal oxide semiconductor logarithmic voltage controlled oscillator

Abstract: Voltage controlled oscillator (50) provides an exponential transfer function. The frequency of the output signal of the voltage controlled oscillator varies exponentially with the input voltages (VIN1, VIN2) to the oscillator. The exponential transfer characteristic is provided by means of a MOS field effect transistor (19) biased in its subthreshold range.

Oscillator with odd- symmetrical characteristics eliminates low-frequency noise sidebands

Abstract: Low-frequency noise in an oscillator normally produces two LF noise sidebands around the center frequency f_{0} of the oscillator. It was shown experimentally that these noise sidebands can be eliminated by using an oscillator circuit with an odd-symmetrical characteristic. A simple theory based on the van der Pol approach to oscillators can explain the observed effects.

Circuit for limiting jitter transients during switching of phase control signals to an oscillator

Abstract: A phase comparator is included with each incoming channel to compare the clock phase of the incoming signal and a local oscillator. The phase comparator of an on-line active unit generates a signal to control the oscillator to maintain its output in phase with the incoming signal. The generated control signal is also connected to capacitor storage in associated channel phase comparators to provide them with an initial starting control voltage when they are switched in to be the receiving channels. Thus eliminating the uncontrolled operation of the oscillator during switching interval.

Relaxation oscillator synchronizer for pulsed laser operation

Abstract: Pulse stability is provided to a pulsed gas filled electrical discharge device by an electrical circuit including first and second electrical energy storage means, with the energy stored in the first storage means being substantially greater than the energy stored in the second storage means. A first voltage corresponding to the energy stored on the first storage means is applied to the input of the gas filled device. A second voltage corresponding to the energy stored on the second storage means is periodically switched to combine with the first voltage and be input to the gas filled device. The period for switching is precisely controlled, preferably with a piezoelectric crystal, and is selected to combine the first and second voltages just before the first voltage reaches the natural breakdown voltage of the gas within the gas filled device.

Oscillator synchronizing system for eliminating static phase errors

Abstract: Non-inverting amplifier, with bandpass filter in regenerative feedback path, forms color reference oscillator in a color TV receiver. Phase shift circuit, responsive to an oscillator output, supplies signals to a first phase shifted signal amplifier, which shares a load with the non-inverting amplifier, and is subject to control by complementary outputs of a phase comparator functioning to compare the phase of an oscillator output with the phase of incoming color synchronizing bursts. A voltage comparator, responsive to the respective phase comparator outputs, is periodically enabled by field rate keying pulses. The voltage comparator output controls the charging or discharging of a capacitor during the keying intervals. A second phase shifted signal amplifier, responsive to the output of the phase shift circuit, and delivering its output to the oscillator's feedback path, is subject to control in dependence upon a comparison of a control voltage derived from the voltage held by the capacitor with a reference DC voltage.

Voltage-controlled oscillator of emitter-coupled astable multivibrator type

Abstract: A resistor, together with a charging capacitor, is connected in series between the emitters of transistors to constitute an emitter-coupled astable multivibrator to be used with a voltage-controlled oscillator. The resistance of the resistor is given by: R.sub.a =(τ.sub.d1 +τ.sub.d2)/2C.sub.a where C a is capacitance of the capacitor and (τ d1 +τ d2 ) is a delay time during one period of oscillation, as determined by the circuit elements.

Oscillator phase lock system

Abstract: A phase-lock system including an oscillator providing a switching output that continuously switches between first and second states, a trigger circuit for inducing switching of the oscillator, a sensing circuit monitoring the switching output and providing an anticipating indication of an imminent switching thereof from the first to the second state, and a primary voltage source providing a variable voltage that periodically varies from and returns to a given voltage level. Also included is a detector circuit monitoring the variable voltage and detecting the presence of the given voltage level and a synchronizing circuit responsive to the sensing and detector circuits and providing an input to the trigger circuit, the synchronizing circuit being operative to cause switching of the oscillator in response to the simultaneous provision of the anticipating indication by the sensing circuit and detection of the given level by the detector circuit.

Recovery system for a control loop

Abstract: Non-inverting amplifier, with bandpass filter in regenerative feedback path, forms color reference oscillator in a color TV receiver. Phase shift circuit, responsive to an oscillator output, supplies signals to a first phase shifted signal amplifier, which shares a load with the non-inverting amplifier, and is subject to control by complementary outputs of a phase comparator functioning to compare the phase of an oscillator output with the phase of incoming color synchronizing bursts. A voltage comparator, responsive to the respective phase comparator outputs, is periodically enabled by field rate keying pulses. The voltage comparator output controls the charging or discharging of a capacitor during the keying intervals. A second phase shifted signal amplifier, responsive to the output of the phase shift circuit, and delivering its output to the oscillator's feedback path, is subject to control in dependence upon a comparison of a control voltage derived from the voltage held by the capacitor with a reference DC voltage. A latching circuit, subject to disabling only when receiver's color killer circuit operates in a color unkilling mode, is switched into a first latched mode of operation if voltage held by capacitor reaches a first extreme of its variation range, said first latched mode of operation forcing an unbalance of a first sense upon the voltage comparator inputs. Latching circuit is switched into a second latched mode of operation, forcing an opposite sense unbalance upon the voltage comparator inputs, if voltage held by capacitor reaches opposite extreme of its variation range.

Nonsymmetric multivibrators with an auxiliary RC-circuit

Abstract: The paper describes the design of nonsymmetric multivibrators. These multivibrators include a large capacitor which is charged by a current source and discharged periodically by the comparator controlled switch. The distinctive feature of these multivibrators is an auxiliary RC-circuit of a small time constant which is connected between the large capacitor and the comparator. The voltage at the output of this auxiliary circuit follows the voltage at the large capacitor during the first quasistable state (space). The recharge of the small capacitor in the auxiliary circuit is used to determine the duration of the second quasistable state (mark). Three modifications are considered. If the space/mark ratio is small (10) the additional buffer amplifier is inserted between the large capacitor-and the auxiliary RC-circuit. For medium ( 100) space/mark ratio multivibrators the buffer amplifier is omitted and the capacitor in the auxiliary RC-circuit absorbs the functions of the large capacitor (which can be omitted also). For large (1000) space/mark ratio the auxiliary RC-circuit is connected to the large capacitor directly. The calculation of both quasistable state durations is given and useful design relationships are established. An example of the multivibrator for different (9, 99 and 999) space/mark ratios is given.

Quantum polarization and dielectric losses at low temperatures

Abstract: We propose a mechanism for the quantum polarization of solid dielectrics, and use it to create and study the kinetic equation taking into account the tunneling of relaxation oscillators. The frequency dependences of both ɛ and tan δ are determined theoretically and compared with experiment. The density of thermally stimulated currents in the dielectrics are calculated. We find that one must take into account tunneling transitions of relaxation oscillators in order to explain the low-temperature features in the dielectric spectra.

An optically controllable negative resistance circuit constructed with optocouplers

Abstract: An optocoupler with a Darlington configuration at the output side can be used as a one port active device with a current-controlled negative resistance by simply connecting the input and output sides in cascade. The author proposes an optically controllable negative-resistance circuit constructed with optocouplers. The breakover voltage and the holding current of the negative-resistance characteristics can be controlled widely with two external light inputs. Hence, the circuit may be applied to optronic functional switching operations. It is demonstrated that an optically controlled relaxation oscillator can be easily constructed using the circuit, and that applications of the relaxation oscillator to a light modulator and an optical Schmitt trigger can be realized by simple circuit configurations.

A simple bridge RC multivibrator

Abstract: A free-running multivibrator for generation of very non-symmetrical waveforms is described. The multivibrator includes a differential pair which functions as a simple comparator, two single-transistor switches and two capacitors. The charge of a large capacitor determines the duration of the first quasi-stable state (space), the recharge of a small capacitor determines the duration of the second quasi-stable state (mark). The calculations of the quasi-stable state durations are given. The circuit can provide a space/mark ratio of the order of 1000-5000 at the frequency of 1 kHz and this ratio becomes larger for smaller oscillation frequencies. The circuit can be retimed for a different oscillation frequency without transient response. The modification with one capacitor for smaller space/mark ratios is considered also.

New constant-current controlled astable multivibrator for generating sawtooth and square waves

Abstract: This article presents a now constant-current controlled astable multivibrator in which only one resistor and one capacitor is used, the other elements being transistors. The circuit consists of a constant-current source and the multivibrator itself. The multivibrator is specifically designed to have a simple three-stage direct-coupled transistor amplifier, with the output of the third stage fed back to the first stage and a capacitor connected across any two collectors. The switching action takes place by means of that capacitor. Linear sawtooth and square waves are generated simultaneously at the transistor collectors. Since only one resistor and one capacitor are required, this circuit is practical with IC fabrication.