Abstract: A Colpitts oscillator includes a tank circuit, a first transistor, and a first feedback circuit. The first transistor includes a first region, a second region, and a control region. The first region communicates with the tank circuit. The first feedback circuit communicates with the second region and the control region of the first transistor.

Abstract: To set a best oscillation state of a voltage-controlled oscillator (VCO) circuit, it is necessary to evaluate variability of manufactured ICs to specify set values based on the variability. Provided is an oscillator including: a terminal receiving a first signal; a VCO coupled to the terminal, the VCO oscillating to generate a second signal and to change a frequency of the second signal in response to an amplitude of the first signal, and revealing gain-slope characteristics in the frequency of the second signal versus the amplitude of the first signal; and a control circuit coupled to the VCO to alter the gain-slope characteristics in response to the amplitude of the first signal, the VCO having so-called self regulating characteristics in which the VCO is locked up based on the variability of the manufactured ICs without depending on external control.

Abstract: A gain control system comprises a reference stage, a bias replication stage, an operational amplifier, an automatic gain control block, a gain stage, and a crystal oscillator in one embodiment. A negative feedback loop is formed by portions of the operational amplifier, the replica biasing stage, the gain stage, and the automatic gain control stage. The negative feedback loop operatively controls an amplitude of oscillation in the crystal oscillator. The automatic gain control block produces output currents at reference levels in proportion to an input current source. The output current reference levels provide a corresponding yet independent scaling of currents in the bias replication stage and the gain stage. By the scaling capabilities provided a high common mode of voltage is provided between the crystal oscillator and the voltage reference section while stable oscillating characteristics are provided over a broad frequency range.

Abstract: Systems and methods for insuring successful initiation of a resonating micro-electro mechanical systems (MEMS). An example system includes a resonating sensor, a drive device, a charge amplifier, and a voltage gain circuit. At start up, the charge amplifier and voltage gain circuit receives signals from the resonating sensor, compensates this signal for DC offsets, and generates a clock signal for the drive, thus placing the resonating sensor in a steady state operating mode. The circuit includes a plurality of gain switches that are toggled to produce a glitch in the signal associated with the received signal. The glitch overcomes the DC offset. A comparator generates the clock signal for the drive device if a signal associated with the received signal exceeds a reference signal.

Abstract: Energy-efficient timing circuits are described. Such circuits may include a biasing circuit configured to provide a control bias current to a voltage-controlled oscillator (VCO). The biasing circuit may repetitively switch between a normal-power operating mode and a reduced-power operating mode. During the normal-power operating mode, the biasing circuit may generate a control voltage representative of a desired control bias current for the VCO. By then storing the control voltage using a device, such as a capacitor, much of the biasing circuit may be turned off during the reduced-power operating mode.

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 low temperature coefficient oscillator including a current generator, a first and a second voltage generator, an amplifier, a resistor, a switch, a capacitor and an oscillating unit is provided. The current generator generates a first through a fourth current according to a control signal. The first voltage generator generates a first voltage according to the first current. The second voltage generator generates a second voltage according to the second current and a frequency signal. The amplifier generates the control signal according the first and second voltages. The resistor is coupled between a first terminal of the switch and ground, and a first terminal thereof receives the third current. The switch is conducted or not according the frequency signal. The capacitor is coupled between a second terminal of the switch and ground. The oscillating unit generates the frequency signal according to the fourth current and a voltage of the capacitor.

Abstract: An oscillator of the present invention includes a constant current circuit in which a constant current generated in the constant current circuit varies positively with an on threshold voltage of a transistor included in the constant circuit; and an oscillating circuit in which the oscillating frequency of a clock signal generated in the oscillating circuit varies positively with the constant current supplied from the constant current circuit, and the oscillating frequency of the clock signal generated in the oscillating circuit varies negatively with an on threshold voltage of a transistor included in the oscillating circuit.

Abstract: A voltage controlled oscillator and a load cell circuit usable in VCO are provided. The VCO features an internal compensation for process, voltage and temperature using a replica of half of the oscillating stage. The load cell circuit comprises a bias transistor to drain a predetermined current from the oscillating stage, a control transistor to vary resistance offered by it responsive to a control voltage applied and a resistor adapted to provide a clamp resistance.

Abstract: The present invention provides a current-limited oscillator capable of performing stable operation even when it is driven with a low power-supply voltage, and a charge pump circuit using the oscillator. A current-limited oscillator has a delay section that includes a plurality of series-connected inverters to delay an output pulse on the basis of a current limiting level indication signal, and the oscillator further includes at least one first transistor that limits a first current between the inverters and a high potential power supply and at least one second transistor that limits a second current between the inverters and a low potential power supply, wherein at least one of the plurality of inverters is configured as a first inverter that is connected with the first transistor and is not connected with the second transistor, and at least another of the plurality of inverters is configured as a second inverter that is not connected with the first transistor and is connected with the second transistor.

Abstract: This invention includes a bias origination section configured to originate an original bias voltage; a comparison section configured to compare the original bias voltage and a comparison voltage, and output a comparison result; a resistive divider section composed by a resistance circuit including a variable resistor section having a resistor and a switch, and configured to generate the comparison voltage; a bias decision control section configured to determine bias decision data for controlling a resistance value of the variable resistor section so as to bring the comparison voltage close to the original bias voltage, based on a comparison result of the comparison section; and a storage section configured to hold the bias decision data and also output the comparison voltage as a bias voltage by controlling a resistance value of the variable resistor section based on the held bias decision data, thereby generating a low-noise bias with a small area.

Abstract: A voltage controlled oscillator (VCO) is provided that includes an output buffer having a first buffer stage including a first transistor and a second buffer stage including a second transistor. The first and second transistors are connected in a cascaded emitter follower buffer arrangement.

Abstract: A circuit includes a voltage-controlled oscillator (VCO), which includes a voltage input node having an input voltage; and a start-up circuit. The start-up circuit includes a first current path and a second current path. The first current path has a first current and is configured so that the first current increases in response to a decrease in the input voltage and decreases in response to an increase in the input voltage. The second current path has a second current and is configured so that the second current decreases in response to the decrease in the input voltage and decreases in response to the increase in the input voltage. The VCO further includes a third current path combining a first proportion of the first current and a second proportion of the second current into a combined current; and a current-controlled oscillator (CCO) including an input receiving the combined current and outputting an AC signal.

Abstract: An interleaved voltage-controlled oscillator (VCO) is disclosed. The VCO includes a ring circuit comprising a series connection of main logic inverter gates, a plurality of delay elements connected in parallel with a selected sequence of the main logic inverter gates, at least one temperature compensation circuit comprising a logic inverter gate in series connection with one or more field effect transistors, the field effect transistor responsive to a compensating voltage input that is proportional to temperature, and an electronic circuit in signal communication with the at least one temperature compensation circuit and configured to provide a voltage signal responsive to temperature. Each delay element includes a feedforward section, comprising controls for regulating signal transmission through feedforward elements responsive to one or more control voltages, and a proportional section, comprising controls for regulating signal transmission through at least one logic inverter gate.

Abstract: An interleaved voltage-controlled oscillator (VCO) is disclosed. The VCO includes a ring circuit comprising a series connection of main logic inverter gates, a plurality of delay elements connected in parallel with a selected sequence of the main logic inverter gates, at least one temperature compensation circuit comprising a logic inverter gate in series connection with one or more field effect transistors, the field effect transistor responsive to a compensating voltage input that is proportional to temperature, and an electronic circuit in signal communication with the at least one temperature compensation circuit and configured to provide a voltage signal responsive to temperature. Each delay element includes a feedforward section, comprising controls for regulating signal transmission through feedforward elements responsive to one or more control voltages, and a proportional section, comprising controls for regulating signal transmission through at least one logic inverter gate.

Abstract: A power source circuit for an oscillator is provided comprising a multiplexer, a plurality of transmission gates, a plurality of resistors, a current source circuit, and an output circuit. The multiplexer inputs a digital signal and outputs one or more control signals. The transmission gates is individually coupled to the multiplexer and receives the one or more control signals, wherein each of the plurality of transmission gates are turned on or off according to the one or more control signals. The plurality of resistors is coupled in series and individually coupled to the plurality of transmission gates. The current source circuit is coupled to the plurality of resistors and provides a current source. The output circuit is coupled to the current source and provides output power for the oscillator according to the current source and the operation of the transmission gates.

Abstract: A differential crystal oscillator circuit uses a bias transistor to generate a bias voltage from a bias current. The bias voltage is supplied to the control terminals of a differential pair of transistors. The differential transistors operate to produce a differential output between corresponding end terminals thereof, which is provided to a reference crystal oscillator to establish an oscillation frequency at the differential output.

Abstract: A method and a voltage-controlled oscillator provide an output signal with a frequency within one of a plurality of frequency bands, while reducing or eliminating temperature-induced band-switching or other drifts in operating frequency. The band-switching is reduced or eliminated by providing a circuit that adjusts a tuning sensitivity according to a calibration performed under test conditions. For example, such a voltage-controlled oscillator may include (a) a digitally controlled variable current source for providing a first control current to select one of the frequency bands for the voltage-controlled oscillator; (b) a variable transconductance circuit providing a second control current to compensate a variation in operating frequency; and (c) a control circuit for varying the frequency of the output signal in accordance with the first and second control signals.

Abstract: A method, system, and circuit device for interfacing single-ended charge pump output to differential voltage controlled oscillator (VCO) inputs to yield low duty cycle distortion from a VCO. A single-ended charge pump output is utilized to create a compliment differential voltage leg, while optimally centering the common-mode voltage level to interface to a current starved ring VCO. A replica of the VCO's current starved delay cell is implemented along with negative feedback to generate the compliment differential voltage leg. The single-ended charge pump output is coupled to a first transistor, while a second transistor is coupled to the output of an error amplifier. The error amplifier utilizes negative feedback to bias the second transistor, forcing the output of the replica circuit to equal a reference voltage.

Abstract: A controllable oscillating system for generating a differential oscillating signal is disclosed. The controllable oscillating system includes an oscillating circuit and a current adjusting device. The oscillating circuit includes a controllable resonator, a cross-coupling driving device, and a current source. The cross-coupling driving device is coupled to the controllable resonator and utilized for driving the controllable resonator to generate the differential oscillating signal. The current source is coupled to the cross-coupling driving device and utilized for providing a first current. The current adjusting device is coupled to the cross-coupling driving device and utilized for adjusting currents passing through the cross-coupling driving device.

Abstract: Control circuitry is disclosed including an oscillator operable to generate an oscillator signal. A frequency of the oscillator signal increases as an amplitude of a first voltage increases up to a threshold, and the frequency of the oscillator signal decreases as an amplitude of the first voltage exceeds the threshold. The oscillator is operable to generate a foldover signal indicating when the frequency of the oscillator signal is decreasing due to the first voltage exceeding the threshold.

Abstract: An oscillation circuit includes a cross-coupled circuit having a first active element and a second active element which are differentially connected to each other. The oscillation circuit oscillates in a resonance frequency of a resonator connected between the first active element and the second active element.

Abstract: An oscillation circuit and the method for operating the same.

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: Methods and apparatus are provided for calibrating a voltage controlled oscillator, such as an N-stage voltage controlled ring oscillator. The voltage controlled oscillator comprises a power supply input and at least one gate delay element and has a frequency that is a function of a delay of the gate delay element and a voltage applied to the power supply input. A voltage controlled oscillator is calibrated by varying an output voltage of a programmable voltage source through a range of values; applying the output voltage to the power supply input of the voltage controlled oscillator; comparing an output clock frequency of the voltage controlled oscillator to a reference frequency clock for each of the output voltage values; and selecting a value of the output voltage that provides an approximate minimum frequency difference between the output clock frequency and the reference frequency clock.

Abstract: A processing device includes a Phase Locked Loop (PLL) system with an adjustable power supply designed to track the power supply provided to one or more of the cores in the processor device. The PLL no longer operates at a fixed voltage level that is held constant and independent from the requested core frequency or the core digital voltage, but rather the power supply to the phase locked loop is adjusted along with the main power supply to the processor core.

Abstract: The integrated circuit package includes a processing core for operating on a set of instructions to carry out predefined processes. A real time clock circuit provides a system clock for the processing core. The real time clock further comprises an internal oscillator that generates the system clock for the integrated circuit package. The internal oscillator has a factory calibrated bias current. An internal oscillator control register controls the operation of the internal oscillator responsive to control bits of the programmable load capacitor array controlled by the processing core.

Abstract: A voltage-controlled oscillator has a resonance tank core providing a voltage-dependent resonance frequency, switching units connected with the resonance tank core for changing output voltage levels of the oscillator with a frequency corresponding to the resonance frequency of the resonance tank core. At least two of the switching units have pairs of Darlington transistors which are connected via a Darlington node. Output terminals are used for outputting the output voltage levels.

Abstract: A voltage controlled oscillator which performs an oscillating operation at a frequency corresponding to a control voltage, includes a voltage-current converter circuit which converts the control voltage to a control current corresponding to a voltage value thereof, and a ring oscillator through which an operating current corresponding to the control current generated by the voltage-current converter circuit is caused to flow, and which oscillates at a frequency corresponding to a current value thereof. The voltage-current converter circuit has a voltage-voltage converting circuit which inputs the control voltage therein and converts the same to a control current corresponding to the voltage value thereof, and an offset current generating circuit which adds a constant current to the control current.

Abstract: A technique for expanding an input signal includes receiving the input signal at a first node of a voltage expander and generating a plurality of expanded signals on different outputs of the voltage expander responsive to the input signal. In certain embodiments, each of the expanded signals has a different magnitude at a respective fixed offset from the input signal.

Abstract: An electrical oscillator circuit comprising: a resonator comprised in the first subcircuit; and an active device comprised in the second subcircuit connected to energize the resonator to provide an oscillating electrical signal transmitted as a differential signal via electrical conductors to the second subcircuit. The oscillator is characterized in that the second subcircuit comprises means for receiving the differential signal transmitted via the electrical conductors and converting the differential signal to a single-ended signal with reference to the signal ground reference of the second subcircuit. Thereby a noise robust oscillator signal is provided with the use of very few components. Particularly suitable for oscillators embodied in an integrated circuit with the resonator mounted on a printed circuit board, PCB. And an integrated circuit.

Abstract: The present invention concerns a differential oscillator device, comprising resonant electronic means, capable to provide on at least two terminals at least one oscillating signal VOUT, which comprises a generator electronic means capable to supply at least one power supply pulsed signal to said resonant electronic means in phase relation with said at least one oscillating signal VOUT. The present invention further concerns a process of supplying pulsed power to such a differential oscillator device.

Abstract: Methods, algorithms, architectures, circuits, and/or systems for increasing voltage controlled oscillator (VCO) operational frequency ranges are disclosed. In one embodiment, a VCO can include 2n+1 transconductors configured to provide an oscillating signal, where n?1; a selectable supply voltage coupled to each of the transconductors, where a frequency range of the oscillating signal is related to the selectable supply voltage; and an adjustable input voltage, where a frequency of the VCO depends on a value of the adjustable input voltage. Also, the VCO may include a voltage regulator configured to provide the supply voltage and/or a selecting circuit configured to select a reference voltage (e.g., from the voltage regulator can produce the supply voltage). Embodiments of the present invention can advantageously provide a cost effective approach for enhancing VCO frequency ranges from a singly VCO, suitable for phase-locked loop (PLL) applications.

Abstract: A stable frequency is outputted by an oscillator circuit including a constant current circuit which is electrically connected between a first terminal and a second terminal, a voltage controlled oscillator circuit in which an oscillation frequency fluctuates in accordance with a potential difference between power supply voltage terminals, an n-channel transistor, a p-channel transistor in which a gate-source voltage is set to be constant by the constant current circuit, and a capacitor, in which a source electrode of the p-channel transistor is electrically connected to the first terminal, a drain electrode of the p-channel transistor is electrically connected a drain electrode and a gate electrode of the n-channel transistor, a source electrode of the n-channel transistor is electrically connected to the second terminal, and a gate electrode of the n-channel transistor is electrically connected to the second terminal through the capacitor.

Abstract: A circuit for generating a clock of a semiconductor memory apparatus is provided. A reference voltage generator is configured to generate a reference voltage. A reference current generator is configured to generate a reference current that has a constant current value regardless of a change in temperature. An oscillator is configured to receive the reference voltage and the reference current to generate a clock that has constant frequency.

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: A wireless communication device is disclosed wherein isolation buffers couple to respective active circuits or stages of the device to convey test information regarding such active circuits to a test data line from which status information may be collected. The communication device operates in two modes, namely a normal operational mode wherein the isolation buffers effectively short spurious emissions from the active circuits to a ground, and a test mode wherein the isolation buffers may convey test information from a selected active circuit to the test data line. The isolation buffers prevent spurious emissions from escaping the active circuits to which they are coupled and prevent spurious emissions from traveling from active circuit to active circuit over the test data line throughout the wireless device.

Abstract: Systems and methods for increasing the frequency range of an output signal generated by a VCO, where one or more variable delay units are incorporated into an interpolative VCO to decrease the minimum frequency at which the VCO oscillates. In one embodiment, the VCO includes a ring of serially connected inverters, a set of bypass circuits and a set of variable delay units. The bypass circuits are coupled to the ring of serially connected inverters to bypass one or more of the serially connected inverters when enabled. Each variable delay unit delays signal transitions at the input of a corresponding one of the serially connected inverters by a variable amount. The variable delay units may be positioned in series with the ring of inverters, in parallel with the bypass paths, or in parallel with corresponding inverters in the ring of inverters.

Abstract: A ring oscillator circuit having an odd plurality of inverter stages (i.e., 2N+1 stages). In accordance with one embodiment of the present invention, only one of the inverter stages is operated in response to a variable input voltage, while the remaining inverter stages are operated in response to a highly filtered constant input voltage. The inverter stages that operate in response to the constant input voltage oscillate at a base frequency. The inverter stage that operates in response to the variable input voltage causes the frequency of the output signal to deviate from the base frequency by an amount determined by the variable input voltage. In this manner, the variable voltage inverter stage implements frequency control for the ring oscillator. The gain of the ring oscillator circuit is reduced by a factor of (2N+1) with respect to the gain of a conventional ring oscillator.

Abstract: In one embodiment, a method of programming an oscillator circuit includes providing a resonator, a first programmable capacitor, a second programmable capacitor, and an amplifier. The first programmable capacitor and the second programmable capacitor may be programmed at a first capacitance value during a first time period, wherein the first programmable capacitor provides a first voltage to bias the resonator and the amplifier alters the second voltage to provide a third voltage to the resonator. During a second time period the first capacitance value is increased.

Abstract: A device for generation of a reference frequency includes a component configured for generating a reference voltage, and a slaving circuit configured for slaving the reference frequency to the reference voltage.

Abstract: In one embodiment, a voltage-controlled oscillator is provided having an output signal whose frequency is responsive to a tuning signal and is independent of amplitude of oscillation. The voltage-controlled oscillator includes: a plurality of differential inverter stages coupled to form a loop, each differential inverter stage having a differential pair of transistors configured to steer a tail current from a current source, the current source sourcing the tail current responsive to a feedback signal; and a control circuit configured to generate the feedback signal responsive to a reference signal such that an amplitude of the output signal is independent of the tuning signal and depends on the reference signal, and the frequency of oscillation is decoupled from the amplitude of oscillation.

Abstract: A phase lock loop pre-charging system and method are described. In one embodiment, a phase lock loop pre-charge system includes a bias component for generating a pre-charge voltage, and an activation component for activating the bias component. In one exemplary implementation the pre-charge voltage is utilized to facilitate pre-charging of a phase lock loop voltage controlled oscillator. In one embodiment, the bias component includes replica bias components that track the voltage controlled oscillation control voltage over varying process, voltage and temperature characteristics. The phase lock loop pre-charging systems and methods can be utilized to reduce lock time for a circuit.

Abstract: An apparatus for characterizing an operating parameter in an integrated circuit, in accordance with one embodiment of the present invention, includes a voltage potential module, a plurality of distribution systems and a plurality of ring oscillator modules. Each ring oscillator module is coupled to the voltage potential module by a respective distribution system. Each ring oscillator module generates an oscillator signal as a function of the voltage potential and a voltage drop caused by the respective distribution system. The characterization of the operating parameter may be extrapolated from the difference in the operating frequencies of the ring oscillator modules.

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: Transistors M11 and M12 are cross-coupled to each other so as to form a negative resistance circuit. First and second variable capacitor sections 10 and 20 are connected in parallel with an inductor circuit so as to form a parallel resonant circuit. A first reference voltage Vref1 and a control voltage VT1 corresponding to a carrier wave component are fed to both terminals, respectively, of each of variable capacitors VC11 and VC12 included in the first variable capacitor section 10. A second reference voltage Vref2 and a control voltage VT2 corresponding to a modulated wave component are fed to both terminals, respectively, of each of variable capacitors VC21 and VC22 included in the second variable capacitor section 20.

Abstract: A feedback loop, such as a phase-locked loop, on an integrated circuit has a detector, a charge pump, and a loop filter. The charge pump adjusts its output current in response to variations in a process of the integrated circuit to reduce variations in the loop bandwidth. The charge pump also adjusts its output current in response to variations in a resistance of a resistor in the loop filter to reduce variations in the loop bandwidth. The charge pump can also adjust its output current in response to variations in a temperature of the integrated circuit to reduce variations in the loop bandwidth. A delay-locked loop on an integrated circuit has a phase detector and a charge pump. The charge pump adjusts its output current in response to variations in the temperature and the process of the integrated circuit to reduce changes in the loop bandwidth.

Abstract: An oscillator is provided that includes an oscillating structure generating an output signal with a frequency that drifts as a function of a parameter of its environment, and a compensation circuit coupled to the oscillating structure. The oscillating structure has a ring structure that includes delay cells looped together, and the compensation circuit supplies a compensation signal to the oscillating structure. The compensation signal varies as a function of changes in the parameter in order to compensate for the drift in the frequency of the generated signal. This makes it possible to compensate for oscillator temperature drifts in the absence of a regulation loop.

Abstract: In a variable frequency oscillator in a semiconductor device, as the variation of an oscillation frequency caused by the variation of temperature and supply voltage and process variation is large, it is difficult to reduce the conversion ratio of control voltage dependent upon phase noise and the oscillation frequency and therefore, phase noise is large. The variation of the oscillation frequency is suppressed and phase noise is reduced by connecting a voltage-to-current conversion circuit that converts input control voltage to control current of a ring oscillator to the ring oscillator where delay circuits a delay time of which increases and decreases according to the amplitude of input control current are cascade-connected by a plurality of stages in a ring and increasing/decreasing current dependent upon any of temperature, supply voltage and the threshold voltage of a transistor inside the voltage-to-current conversion circuit.

Abstract: A high frequency signal detection circuit includes an input terminal for a high frequency signal to be detected, a switch transferring the high frequency signal as intermittent ringing signal to a first node in response to a pulse signal whose frequency is lower than that of the high frequency signal, a transistor amplifying the signal at the first node, and outputting to a second node, a bias generator generating a bias voltage by which the transistor is operated in its weak inversion region, a resonant circuit outputting the bias voltage to the first node, and resonating the high frequency signal, a capacitor removing a high frequency component of the signal at the second node; and a judgment circuit judging whether or not the high frequency signal is inputted by detecting the signal at the second node, which has the same frequency as the pulse signal.