Abstract: An oscillation control apparatus is provided with: an oscillating unit for oscillating an oscillating element; an output amplifying circuit having two pieces of same types of transistors series-connected to each other, for outputting a signal from a junction point between the two transistors in response to an oscillation signal outputted from the oscillating unit; a bias unit for generating two DC bias voltages having different levels from each other, which are applied to either respective gates or respective bases of the two transistors; a constant voltage power supply unit for applying a constant voltage to the oscillating unit; and an inverter unit provided between the oscillating unit and any one of either the gates or the bases of the two transistors, for inverting a phase of the oscillation signal outputted from the oscillating unit.

Abstract: A voltage controlled oscillator controls an oscillation frequency based on a control voltage supplied from an external control voltage terminal. The voltage controlled oscillator includes a reference bias voltage circuit and a gain adjustment circuit. The reference bias voltage circuit includes multiple serial resistances between a reference voltage and a ground. The reference bias voltage circuit controls a switch coupled in parallel to at least one of the serial resistances and thus changes a voltage dividing ratio of the serial resistances so as to set a reference bias voltage. The gain adjustment circuit adjusts a gain of the control voltage. The gain adjustment circuit includes multiple resistances and multiple switching elements. The gain adjustment circuit controls the switching elements to form a voltage dividing circuit between the reference bias voltage and the external control voltage terminal so as to generate an automatic frequency control voltage.

Abstract: A modulator including a direct modulation synthesizer circuit, a reference frequency oscillator for providing an input reference signal to the direct modulation synthesizer circuit for locking a carrier frequency to a stable frequency and a pre-emphasis unit for data bits and for producing a modulating signal for direct modulation of the direct modulation synthesizer circuit, the modulating signal having data bit dependent voltage levels.

Abstract: A ring oscillator based voltage controlled oscillator (VCO) is disclosed. The VCO includes a set of delay cells connected to each other in a ring configuration. Each of the delay cells includes a source-coupled input transistor pair, a current-steering transistor pair and a pair of load resistors. The source-coupled input transistor pair receives a pair of differential voltage inputs. The load resistors, which are connected to the source-coupled input transistor pair, provide a pair of differential voltage outputs. The current-steering transistor pair, which is connected to the source-coupled input transistor pair, receives a pair of differential bias voltage inputs. The output frequency of the VCO is directly proportional to the differential bias voltages at the pair of differential bias voltage inputs.

Abstract: A power supply circuit includes a first voltage regulator to generate a first supply voltage for a first circuit of a phase-locked loop and a second voltage regulator to generate a second supply voltage for a second circuit of the phase-locked loop. The first and second supply voltages are independently generated by the first and second voltage regulators based on the same reference signal. The first circuit may be a charge pump and the second circuit may be a voltage-controlled oscillator. Different circuits may be supplied with the independently generated supply voltages in alternative embodiments.

Abstract: A crystal oscillator circuit includes a capacitive load stage coupled to a crystal; an amplifier stage including an amplifying transistor coupled to the crystal and to the capacitive load stage for establishing an oscillation signal at the amplifier stage output and a bias generator stage coupled to the amplifying transistor; an amplitude control stage to control the amplitude of the oscillation signal; a pick-up stage coupled to the amplifier stage and to the crystal to generate an oscillator output signal. The bias generator stage is configured as a degenerated common source amplifier.

Abstract: Constant and accurate signal gain systems based on controlling oscillator loop gain. A constant gain positive feedback network and an amplifier form an oscillator. Only when the oscillator loop gain is at least one does the oscillator produces an AC signal. Negative feedback of the oscillator's AC signal level is used to keep the loop gain close to or at the value of one by controlling the loop gain of the oscillator circuit. By maintaining the loop gain of the oscillator circuit substantially constant the signal gain is also maintained substantially constant.

Abstract: A voltage controlled oscillator that is a differential ring oscillator type voltage controlled oscillator that, by connecting in cascade differential delay elements to which differential clock signals of a mutually reverse phase are input and controlling the current that flows to the differential delay elements by a bias voltage, controls a delay amount of this differential clock signal, having a phase detection portion that outputs a detection signal by comparing an output voltage of the differential output of any differential delay element and a reference voltage that is set to a voltage that detects an abnormal operation, and a cross-coupled circuit that is provided at each of the differential delay elements and, when the detection signal is input, amplifies the potential difference between the pair of differential output terminals.

Abstract: A crystal oscillator with variable gain and variable output impedance inverter system includes an inverter, a variable impedance feedback circuit, connected between the output and input of the inverter, a crystal oscillator system, having a crystal with first and second electrodes connected across the input and output of the inverter; a serial variable impedance circuit connected between the inverter output and an electrode of the crystal and a control circuit for temporarily, during start up mode, increasing the impedance of the feedback circuit and decreasing the impedance of the serial circuit relative to the stationary mode impedances and then returning the feedback impedance to the lower impedance level and the serial circuit to the higher impedance level that promotes high frequency stability of the oscillator in the normal, stationary mode, of operation.

Abstract: A voltage controlled oscillator (VCO) with improved frequency characteristics is provided. The VCO includes a converting circuit supplied between a bias voltage and a ground voltage for converting the control voltage into a control current, a replica bias circuit coupled to the converting circuit for providing a swing voltage, and a ring oscillating circuit coupled to the replica bias circuit having at least two delay units coupled in series for successively delaying an input signal as the oscillating signal after a period of delay time.

Abstract: A voltage-controlled oscillator includes: a bias voltage generator operating to generate first and second bias voltages in response to a control signal; a voltage-controlled oscillation circuit connected to a control node and configured to generate oscillation signals in response to an input voltage; a selection signal generator operating to generate a selection signal in response each to the oscillation signals; and a selection circuit operating to select one of the first and second bias voltages in response to the selection signal and outputting the selected bias voltage to the control node.

Abstract: An oscillation driver device includes a gain control amplifier, an automatic gain control circuit, and a mode setting circuit. When the mode setting circuit has switched a mode from a normal operation mode to a low power consumption mode, the automatic gain control circuit is disabled, and the gain in an oscillation loop that drives the vibrator changes from a state in which the gain in the oscillation loop is controlled to be unity by the automatic gain control circuit to a state in which the gain in the oscillation loop is set to be larger than unity. When the mode setting circuit has switched the mode from the low power consumption mode to the normal operation mode, the automatic gain control circuit resumes operation, and the gain in the oscillation loop changes from the state in which the gain in the oscillation loop is set to be larger than unity to the state in which the gain in the oscillation loop is controlled to be unity by the automatic gain control circuit.

Abstract: The present invention relates to an oscillating circuit arrangement having a resonating arrangement with a first resonance frequency (coo) comprising a voltage controlled oscillator arrangement. It further comprises a tunable filter arrangement connected to the source node of said voltage controlled oscillator (VCO) arrangement. Said filter arrangement particularly comprises an equivalent current source resonating at a second resonance frequency c?f, the second resonance frequency being a multiple n, n=1 or 2 of said first resonance frequency (?>o), n being equal to the minimum number of switch transistors required for oscillation of said VCO arrangement. The filter arrangement particularly comprises an inductor connected in parallel with a capacitor, said capacitor being adapted to be tunable such that the phase noise of the resonating arrangement can be minimized through tuning of the filter arrangement.

Abstract: To maintain the amplitude of an oscillating signal within a defined range, the detected peak level of the oscillating signal is compared to a reference voltage. If the detected peak level is determined as being greater than the reference voltage, the common source/drain voltage of a differential amplifier driving the crystal oscillator across its input terminals is reduced so as to lower the amplitude of the oscillation signal. If the detected peak level is determined as being smaller than the reference voltage, the common source/drain voltage of the differential amplifier driving the crystal oscillator is increase so as to raise the amplitude of the oscillation signal.

Abstract: A clock circuit has a crystal. A differential amplifier has a first input coupled to a first node of the crystal and a second input of the differential amplifier coupled to a bias signal and an output of the differential amplifier coupled to a second node of the crystal.

Abstract: A system for providing voltage and current regulator sources based on a oscillator having variable loop gain is described. Only when the oscillator loop gain is at least the value of one does the oscillator oscillate. The oscillator's ability to oscillate is controlled by the one or more variable impedance or gain devices. Negative feedback of the voltage or current output level is used to control the loop gain of the oscillator circuit.

Abstract: Provided is a voltage controlled oscillator to which a switching bias technique is applied so as to lower flicker noise of a bias circuit and enhance phase noise characteristics, thereby reducing the overall chip area to make it possible to achieve integration. A common mode voltage applied to the bias circuit is negatively fed back to an oscillation waveform. Therefore, it is possible to stabilize the magnitude of the oscillation waveform of the voltage controlled oscillator with respect to a change in an external condition.

Abstract: In one embodiment, a signal control system has a signal output and includes: 1) a phase-locked loop (PLL) having a voltage-controlled oscillator (VCO), a phase error detector, an oscillating output coupled to the signal output of the signal control system, and a programmable frequency divider coupled in a feedback path between the oscillating output and the phase error detector; 2) at least one automatic level controller (ALC), coupled to the oscillating output; and 3) a plurality of switchable integrators, including first and second switchable integrators that are respectively coupled between the phase error detector and the VCO, and in the at least one ALC. Each of the switchable integrators is switchable between a narrow bandwidth mode that provides for stable operation of the signal control system, and a wide bandwidth mode that enables fast signal transitions at the signal output.

Abstract: An amplitude regulating circuit for an oscillator with an input for a supply signal having an electrical quantity depending on an amplitude of an oscillation of the oscillator has a supply circuit with a control input for a first control signal and a supply output for the supply signal based on the first control signal, a reference circuit with an input for a reference supply signal having a reference quantity, a reference supply circuit with a reference control input for a second control signal and a reference supply output for the reference supply signal based on the second control signal and a comparator circuit with a first control signal output for the first control signal based on the electrical quantity and the electrical reference quantity and a second control signal output for the second control signal based on the electrical quantity and the electrical reference quantity.

Abstract: An oscillator circuit may be used with controller circuits that are designed to operate with crystals, with no modifications to the pinout or firmware of the controller circuit. In some embodiments, the oscillator circuit includes an enable input that is responsive to low-amplitude transitions, which may be coupled to and driven by the crystal output signal of the controller circuit. When transitions are present on the crystal output signal, the oscillator circuit enables its clock output signal. When the controller circuit disables its crystal output signal, the oscillator circuit no longer detects transitions on the crystal output signal coupled to the oscillator circuit enable input, and disables the clock output signal.

Abstract: An oscillator circuit may be used with controller circuits that are designed to operate with crystals, with no modifications to the pinout or firmware of the controller circuit. In some embodiments, the oscillator circuit includes an enable input that is responsive to low-amplitude transitions, which may be coupled to and driven by the crystal output signal of the controller circuit. When transitions are present on the crystal output signal, the oscillator circuit enables its clock output signal. When the controller circuit disables its crystal output signal, the oscillator circuit no longer detects transitions on the crystal output signal coupled to the oscillator circuit enable input, and disables the clock output signal.

Abstract: The disclosure relates to an automatic level control technique for RF amplifiers in a communication system, such as a wireless communication system. The invention provides an automatic level control technique to compensate for variations in the gain of an RF amplifier, which may be a transmitter amplifier or a receiver amplifier. In accordance with the invention, the gain of the RF amplifier can be controlled as a function of the output of a voltage controlled oscillator (VCO) circuit provided in the communication system. A VCO typically includes a buffer amplifier with a structure similar to that of the RF amplifier used in the transmit or receive side of the RF front-end. By tracking changes in the output of the VCO buffer amplifier, an automatic level control (ALC) input to the RF amplifier can be adjusted to compensate for process- and temperature-based variations in amplifier gain.

Abstract: Embodiments of the present invention provide a system for controlling a startup time of an oscillator circuit. The system includes a variable current source coupled to the oscillator circuit, wherein a startup time of the oscillator circuit is proportional to a bias current input into the oscillator circuit from the variable current source. The system also includes a control mechanism coupled to the variable current source and to the output of the oscillator circuit. Upon startup, the control mechanism is configured to adjust the variable current source to input a large startup bias current into the oscillator circuit. After the oscillator circuit outputs a predetermined number of oscillations during startup, the control mechanism is configured to adjust the variable current source to decrease its current to a smaller steady-state bias current into the oscillator circuit.

Abstract: An apparatus comprising a first circuit and a second circuit. The first circuit may be configured to generate an output signal oscillating at a frequency in response to a first control signal and a second control signal. The second circuit may be configured to generate the second control signal in response to (i) an input voltage and (ii) the output signal. The second circuit (i) generates the second control signal by comparing a peak voltage of the output signal to the input voltage and (ii) adjusts an amplitude of the control signal in response to the comparison.

Abstract: Embodiments of the invention may provide for an LC quadrature oscillator that includes two LC oscillators that are cross-coupled with each other to generate I/Q clock signals and a phase and amplitude mismatch compensator. The phase and amplitude mismatch detector may include an amplitude mismatch detector, a transconductor, and a capacitor for compensating for both phase and amplitude mismatches between I/Q clock signals generated in the LC quadrature oscillator.

Abstract: Embodiments provide systems and methods for supporting reliable operation of crystals with widely varying fundamental modes of oscillation. In accordance with exemplary embodiments, an architecture is disclosed for an oscillator circuit which allows reliable operation for crystals varying over a wide frequency range, such as 12:1. Some embodiments use selectable current sources to provide variable range control for extending the range of frequencies over which the embodiments may operate properly. Other embodiments include symmetric topologies, cascode topologies, coupling elements, and/or other techniques to improve noise immunity and/or operation in low-source-voltage environments.

Abstract: Disclosed are circuits and methods to control the amplitude of a signal generated by a VCO.

Abstract: A self-biasing negative transconductance LC oscillator that uses self-biasing circuitry to regulate a current source that feeds negative transconductance circuitry and direct current (DC) bias circuitry to apply a DC bias between control inputs and outputs of the negative transconductance circuitry is disclosed. A current source setpoint is based on the voltage swing of the oscillator, which can then be controlled by the DC power supply that powers the oscillator. In one embodiment of the present invention, the negative transconductance circuitry includes a pair of p-type metal oxide semiconductor (PMOS) cross-coupled field effect transistors (FETs), which have a limit applied to their gate to source voltages. Limiting the gate to source voltages of the FETs limits the percentage of the oscillation cycle that the FETs spend in the triode region and thus reduces the noise contribution of the FETs and allows for less power consumption for a given noise requirement.

Abstract: An apparatus comprising a first circuit and a second circuit. The first circuit may be configured to generate an output signal oscillating at a frequency in response to a first control signal and a second control signal. The second circuit may be configured to generate the second control signal in response to (i) an input voltage and (ii) the output signal. The second circuit (i) generates the second control signal by comparing a peak voltage of the output signal to the input voltage and (ii) adjusts an amplitude of the control signal in response to the comparison.

Abstract: An oscillation circuits includes an oscillation unit 30 for generating an internal clock signal having an amplitude of vibration corresponding to an internal power supply voltage thereof, switches 28, 29, a NMOS 13 of a tolerant input circuit, a first-stage driver 15, and a coupling capacitance 27. The switches 28, 29 are turned off when the external clock signal is inputted to a clock terminals 1, 2, and are turned on when the oscillation unit 30 oscillates. The NMOS 13 changes the amplitude of the input clock signal by the on-resistance and the outputs the above input clock signal from the drain electrode. The first-stage driver 15 drives the output of the drain electrode of the NMOS 13 and outputs the output thereof as a clock signal. The coupling capacitance 27 changes the gate voltage of the NMOS 13 when the input clock signal rises so as to keep the above on-resistance constant.

Abstract: A method for assisting the oscillating starting process of an electromechanical oscillator (10) has the following steps: detection of oscillator oscillations (1b, 1c) which occur in the output signal (1a) from the electromechanical oscillator (10); generation of an excitation pulse (3b) on the basis of a detected oscillator oscillation (1c); and feeding (3a) of the excitation pulse (3b) to the electromechanical oscillator (10).

Abstract: Provided is an LC resonance voltage-controlled oscillator (VCO) used for a multi-band multi-mode wireless transceiver. In order to generate a multi-band frequency, a capacitor bank and a switchable inductor are included in the LC resonance voltage-controlled oscillator. The LC resonance voltage-controlled oscillator employs an adjustable emitter-degeneration negative resistance cell in place of tail current sources in order to compensate for non-uniform oscillation amplitude caused by the capacitor bank and prevent the degradation of a phase noise due to the tail current sources.

Abstract: Systems and methods are provided. In this regard, a representative system incorporates a crystal oscillator circuit and a digital automatic level control circuit. The digital automatic level control circuit is operative to: convert an oscillation amplitude of the crystal oscillator circuit to a proportional DC voltage; convert the DC voltage to a corresponding digital code representation; and adjust bias current and oscillator loop gain such that a desired oscillation amplitude is set.

Abstract: Exemplary embodiments of the invention provide a reference signal generator, system and method. An exemplary apparatus to generate a harmonic reference signal includes a reference resonator, such as an LC-tank, and a common mode controller. The reference resonator generates a first reference signal having a resonant frequency, and the common mode controller maintains substantially constant a common mode voltage level of the reference resonator. An amplitude controller may also be included to maintain substantially constant a magnitude of a peak amplitude of the first reference signal. A temperature-dependent control voltage also may be generated and utilized to maintain the resonant frequency substantially constant or within a predetermined variance of a calibrated or selected frequency.

Abstract: An oscillator arrangement having a resonator and a drive circuit which is connected to a connecting terminal of the oscillator is disclosed. In one embodiment, the oscillator includes a current source circuit is connected between a terminal for a first supply potential and the connecting terminal of the resonator and supplies the connecting terminal with a current source current which varies periodically at an oscillator frequency. A current sink circuit is connected between the connecting terminal of the resonator and a second supply potential, where the current sink circuit draws a current sink current from the connecting terminal, said current sink current varying periodically at the oscillator frequency and being negatively fed back to the current source current.

Abstract: An oscillator circuit having a closed loop connection, including: an oscillator for generating an output signal oscillating at a frequency corresponding to a control signal; a frequency/voltage converter for generating a detection signal having a voltage corresponding to a frequency of the output signal; a difference detector for generating a difference signal indicating a difference between the detection signal and a reference signal; and an integrator for generating the control signal by integrating the difference signal.

Abstract: An oscillator device comprises an oscillator core, a capacitive loading unit having a controllable capacitance value and being connected to the oscillator core, and a memory device including a first and a second memory unit and being connected to the capacitive loading unit. The first memory unit is adapted to store a first value to be supplied to the capacitive loading unit for controlling the capacitance value during a start-up time period. The second memory unit is adapted to store a second value to be supplied to the capacitive loading unit for controlling the capacitance value during an operational time period. According to a method for start up of the oscillator device, the amplitude of an oscillator signal is measured. Further, the starting-time instant for the operational time period is chosen as the time instant when the oscillator signal exceeds a predetermined threshold value.

Abstract: A voltage controlled oscillator includes a first NMOS transistor having a base terminal configured to receive an input signal INP and a drain terminal connected to an output node OUTN, a second NMOS transistor having a base terminal configured to receive an input signal INN and a drain terminal connected to an output node OUTP, a third NMOS transistor having a source terminal connected to a low voltage supply VSS and a drain terminal connected to source terminals of the first NMOS transistor and the second NMOS transistor. A first PMOS transistor includes a base terminal connected to the output node OUTP and a drain terminal connected to the output node OUTN. A second PMOS transistor includes a base terminal connected to the output node OUTN and a drain terminal connected to the output node OUTP.

Abstract: An oscillator circuit may be used with controller circuits that are designed to operate with crystals, with no modifications to the pinout or firmware of the controller circuit. In some embodiments, the oscillator circuit includes an enable input that is responsive to low-amplitude transitions, which may be coupled to and driven by the crystal output signal of the controller circuit. When transitions are present on the crystal output signal, the oscillator circuit enables its clock output signal. When the controller circuit disables its crystal output signal, the oscillator circuit no longer detects transitions on the crystal output signal coupled to the oscillator circuit enable input, and disables the clock output signal.

Abstract: It is therefore the object of the present invention to disclose a device for power calibration of an oscillator in the high-frequency range, which has a reduced number of components and/or has less-expensive components. A method for power calibration of an oscillator is also to be disclosed, which eliminates the disadvantages of the known methods, that is, determining the output power of the oscillator via an additional, expensive component. To that end, the input (31) of the control module (40) is embodied as electrically connectable to the HF switch (comprising (22) and (24)) and the output (34) of the control module (40) is embodied as electrically connectable to the HF switch and/or to the amplifier.

Abstract: Disclosed are circuits and methods to control the amplitude of a signal generated by a VCO.

Abstract: Circuits and methods for generating an oscillator output. The circuit generally includes a ring oscillator, with a series of inverters connected in series and an LC resonator tank (or a variable resistance) coupled to the input and output of the inverter series. The method generally includes the steps of applying an operating voltage to such a circuit and generating an oscillator signal. The circuits and methods may be employed as a VCO component of a phase-locked loop. The upper limit of the oscillator signal frequency may be configured by altering or controlling the variable resistance and/or one or more parameters of the LC resonator tank. The circuit design demonstrates a high tolerance to variations in circuit or circuit component values.

Abstract: Circuits, methods, and apparatus that provide low-noise, high-stability crystal oscillators having controlled-amplitude differential output signals and DC level control. A crystal oscillator circuit has two feedback loops, one for setting the DC level of its signals, the other for adjusting the amplitude of those signals. The DC level feedback loop can set the DC component of the oscillator signals to a voltage midway between two supply voltages. The amplitude control loop sets the amplitude of the output of the crystal oscillator signal to be within a range. The amplitude can be set to provide a maximum swing without clipping the supply voltages in order to provide high-stability and minimal jitter. The amplitude control circuit can also be digital for improved noise performance. The time constants of these two loops can be separated such that instabilities are avoided.

Abstract: The present invention pertains to an oscillator arrangement for carrying out a frequency modulation process, wherein an oscillator (1) with automatic amplitude control (5, 6, 7) is provided. The shift keying is not realized with reconnectable capacitances in the oscillator (1) that determine its oscillator frequency, but rather by suitably influencing (6) the feed current of the oscillator in dependence on the modulation signal (FSK), namely with the aid of the amplitude control (5, 6, 7). Undesirable charge injections do not occur in the proposed oscillator arrangement because reconnectable capacitances are no longer required for achieving the desired frequency deviation.

Abstract: A method for operating a torsion oscillator at its resonant frequency. The method performs an open-loop frequency sweep starting with nominal operation parameters saved from the factory or from a previous operation of the torsion oscillator. The sweep determines an open-loop resonant frequency and an open-loop drive level. A closed-loop resonant frequency sweep is performed and a closed-loop steady-state resonant frequency is determined. This frequency is used to calculate a closed-loop overshoot and a closed-loop steady-state drive level. The torsion oscillator is then operated in a closed-loop mode at the closed-loop steady-state resonant frequency and starting at the closed-loop steady-state drive level. Finally, the nominal operation parameters are updated and stored in non-volatile memory. The method minimizes the effects of ambient environmental conditions including air density on the steady-state operation of the torsion oscillator.

Abstract: One embodiment of the present invention includes a frequency generation circuit including a control module, an oscillator circuit coupled to the control module, the oscillator circuit having a start-up time defined by the time required to reach a desired frequency. The oscillator circuit includes an amplifier having an input and an output and being programmably-alterable by the control module, a first capacitor coupled to the input of the amplifier and being programmably-alterable, in capacitance, by the control module, a second capacitor coupled to the output of the amplifier, a crystal resonator coupled to the first and second capacitors for generating an output signal having a desired frequency, wherein fast start-up time is achieved.

Abstract: A frequency source having a fast start-up time and low noise in steady state is presented. The frequency source includes an oscillator and a hybrid automatic gain control (AGC) loop that switches between an analog AGC loop at oscillator start up and a digital AGC loop at steady state operation. The analog AGC loop includes a peak detector connected to the oscillator and an error integrator integrating the difference between the peak detector output and a reference voltage. The digital AGC loop includes a comparator comparing the peak detector output and high/low reference voltages, an oscillator counter providing a timer signal, a digital-to-analog converter (DAC) supplied with a digital word, and a low pass filter between the DAC and the oscillator. The timer signal causes a multiplexer to select either the analog AGC loop or the digital AGC loop.

Abstract: A digitally controlled oscillator circuit is provided that comprises a ring oscillator including multiple inverters; multiple digitally controlled capacitors (DCCs), each coupled to apply a digitally controllable amount of capacitance to an output of a different one of the inverters; and control circuitry operable to change an amount of capacitance applied to each inverter during operation of the ring oscillator and to cause the multiple DCCs to apply substantially the same amounts of capacitance to each of the inverter throughout operation of the ring oscillator.

Abstract: An inverting circuit comprises a first inverter in a main path having a first input and a common ouput. A second inverter receives the first input and is coupled with a first voltage controlled pass gate to the common output. A third inverter couples a second input to the common output using a second voltage controlled pass gate. A fourth inverter couples the second input to the common output using the first voltage controlled pass gate. A ring oscillator is formed using a number N of the inverting circuits with each common output coupled to the first inputs forming a main ring of a ring oscillator. The second inputs are coupled to feed-forward signals from selected outputs. The resulting signals at the common outputs are an interpolation of the first and second input signals modulated by a control voltage coupled to the first and second pass gates.

Abstract: A semiconductor integrated circuit includes a reference-voltage circuit configured to produce a predetermined reference voltage at an output node thereof, a comparator, coupled to a node to which an oscillating signal is supplied and to the output node of the reference-voltage circuit, to produce a result of comparison at an output node thereof, the result of comparison being made by comparing a voltage of the oscillating signal with the predetermined reference voltage, and a detection circuit coupled to the output node of the comparator to produce, in response to the result of comparison, a stable-state-detection signal indicating that the oscillating signal has an amplitude larger than the reference voltage.