Abstract: It is an object of the present invention to provide a phase locked loop in which a voltage signal input to a voltage controlled oscillator after a return from a stand-by state becomes constant in a short time and power consumption is reduced. A transistor including a semiconductor layer formed using an oxide semiconductor material is provided between an input terminal of a voltage controlled oscillator and a capacitor of a loop filter. The transistor is turned on in a normal operation state and turned off in a stand-by state.

Abstract: An analog to digital conversion includes a multiplexor circuit for receiving analog input signals and, responsive to a select input, an analog to digital converter circuit to convert a selected analog signal into a digital signal, a conversion starting device to send a conversion start signal on the basis of a trigger event, the conversion starting device being responsive to a select input, a sequencer to control the analog to digital converter circuitry to execute one sequence conversion on the basis of one conversion sequence instruction, and a FIFO register block to receive conversion sequence instructions and being able to queue each new received conversion sequence instruction if an actual conversion sequence is in progress and to control the sequencer to execute a new sequence conversion instruction after the conversion sequence is executed.

Abstract: A terminal includes control logic to control a phase-locked loop to output a spread-spectrum clocking signal. The control logic controls the generation of the spread-spectrum clocking signal by adjusting at least one parameter of the phase-locked loop. The parameter may be a charge pump setting or a loop-filter capacitance of the phase-locked loop, or their digital equivalents. Adjustment of the parameter reduces a predetermined portion of a communications spectrum. The predetermined portion may be located within a range of frequencies allocated to a specific channel, and reduction of the spectrum in this range may serve to reduce noise associated with clocking harmonics.

Abstract: A PLL circuit includes: a phase comparator for detecting a phase difference between a reference signal and a feedback signal; a first charge pump for outputting a current Ipr according to a detection result of the phase comparator; a second charge pump for outputting a current Iint according to the detection result of the phase comparator; a filter for outputting a current Iprop from which a high frequency component of the Ipr is removed; an integrator for integrating the Iint; a voltage-current conversion circuit for outputting a current Ivi according to an integrated result of the integrator; and an oscillator that generates an oscillating signal of a frequency according to a current Iro, a sum of the Iprop and the Ivi, and feeds it back to the phase comparator.

Abstract: A shared loop filter includes an input port configured to selectively receive a first input from a first charge pump. The first charge pump is connected to a first phase locked loop (PLL) in a first die. The input port is further configured to selectively receive a second input from a second charge pump, the second charge pump connected to a second PLL in a second die separate from the first die. The shared loop filter further includes an output port configured to selectively provide an output to a first voltage controlled oscillator (VCO). The first VCO is connected to the first PLL. The output port is further configured to selectively output a second output to a second VCO. The second VCO is connected to the second PLL.

Abstract: A phase-locked loop (PLL) circuit is provided. The PLL circuit includes a phase frequency detector (PFD), a first charge pump (CP), a second CP, a first loop component set, a second loop component set, a voltage control oscillator (VCO) and a frequency divider. The first CP and the second CP are coupled to the PFD. The first loop component set is coupled between the first CP and the VCO. The second loop component set is coupled between the second CP and the VCO. The frequency divider is coupled between the PFD and the VCO. The first loop component set generates an offset current to adjust the working range of the first CP and the second CP. The second loop component set generates an offset current and a DC adjustment voltage to control the control voltage outputted to the VCO.

Abstract: A time-to-digital converter converts the difference between transition times of a reference clock signal and an oscillating signal to a digital signal whose value is proportional to the transitions timing difference. The time-to-digital converter includes an edge detector, a time-to-voltage converter, and an analog-to-digital converter. The edge detector is adapted to detect, during each period of the reference clock signal, the edge (transition) of the oscillating signal that is closest to the edge of the reference clock signal. The time-to-voltage converter is adapted to generate an analog signal proportional to a difference in time between the detected edge of the oscillating signal and the edge of the reference clock signal. The analog-to-digital converter is adapted to convert the analog signal to a digital signal whose value is proportional the difference between the occurrence of the detected edge of the oscillating signal and the edge of the reference clock signal.

Abstract: A pipeline analog-to-digital converter is disclosed which includes at least one periodic unit consisting of two adjacent stages that jointly use two capacitor networks of the same structure. Each of the capacitor networks includes two identical capacitors, two switches and four terminals. On/off states of the switches and interconnection configuration of the terminals are controlled by clock signals to switch the periodic unit between four possible connection configurations. During operation of the periodic unit, when the upstream stage is in a sampling phase that involves one of the capacitor networks as well as a reference capacitor, the downstream stage uses the other of the capacitor networks to conduct residue amplification; and on the other hand, when the upstream stage is using one of the capacitor networks for residue amplification, the downstream stage relies also on this capacitor network for sampling, leaving the other of the capacitor networks idle.

Abstract: A reconfigurable circuit is disclosed. The reconfigurable circuit comprises a pause detector mechanism, a clock extractor, and a multiplexer. The multiplexer is configured to receive a reference clock and is coupled to the clock extractor to receive a clock extracted from a carrier of a near field communication (NFC) field. The reconfigurable circuit also comprises a phase locked loop (PLL) coupled to the pause detector mechanism and the multiplexer, and the PLL can be configured in a first mode to be locked to the reference clock, in a second mode to be locked to the extracted clock, and in a third mode wherein the PLL can switch between being locked to the reference clock and being locked to the extracted clock.

Abstract: A system and method are disclosed for performing on die jitter tolerance testing. A set of clocks are generated based on an input signal. The set of clocks include in an in-phase signal based on the data switching edge of the input signal. Additionally, the set of clocks include an inverted clock phase shifted by 180 degrees, and a pair of clocks phase shifted positively and negatively by a certain number of degrees, ?. Data input is sampled based on the inverted clock and the two phase shifted clocks. The eye opening of the input signal can be determined based on whether each of the inverted clock and the two phase shifted clocks sample the correct data from the input signal at various ? values.

Abstract: The present invention is directed to signal processing system and electrical circuits. More specifically, embodiments of the present invention provide a DLL system that provides phase correction by determining a system offset based on phase differences among the delay lines. The offset is used as a part of a feedback loop to provide phase corrections for the delay lines. There are other embodiments as well.

Abstract: A synchronizing circuit that is capable of generating a reproduced clock signal synchronized with a reference clock signal without causing a false lock and a clock data recovery circuit including the same are provided. To generate a clock signal synchronized with a reference clock signal associated with a data transition point that appears every predetermined period in an input data signal, the following false-lock avoidance processing is performed. That is, precharging of a first line is started when a phase control voltage applied to the first line by a charge pump falls below a lower-limit reference voltage, and the precharging of the first line is continued until the phase control voltage exceeds an upper-limit reference voltage.

Abstract: A circuit adapted to generate a high speed shaped pulse comprising an input adapted to receive a data signal and a control signal. A plurality of logic elements are configures to receive the data signal and the control signal and generate a plurality of output signals representative of the shaped pulse. A digital to analog converter is adapted to receive the plurality of output signals and generate a shaped pulse.

Abstract: Disclosed herein are a delay-locked loop circuit using a phase inversion locking algorithm and a method of controlling the same. There is provided a delay-locked loop circuit using a phase inversion locking algorithm, including a phase inversion controller configured to control whether or not to use the phase inversion locking algorithm by determining a phase error between an input clock signal and an output clock signal, an inverter configured to invert the input clock signal and output the inverted input clock signal, a multiplexer configured to receive the input clock signal and the inverted input clock signal of the inverter and output the input clock signal in response to the control signal of the phase inversion controller or the inverted input clock signal, and a delay-locked loop connected to the output terminal of the multiplexer and configured to perform phase synchronization in response to the output signal of the multiplexer.

Abstract: A method includes providing an active circuit element in a feedback path between an output node and a bypass node of a charge pump of a Phase Locked Loop (PLL). The bypass node is a node to which a charge current or a discharge current is steered to by the charge pump when neither charging the output node nor discharging the output node is required. The method also includes servoing the bypass node to the output node through the active circuit element in the feedback path to maintain a same voltage at the output node and the bypass node when neither the charging of the output node nor the discharging of the output node is required.

Abstract: A phase-locked loop circuit includes an oscillator circuit that generates a clock signal. The oscillator circuit has gears. Each of the gears of the oscillator circuit corresponds to a respective frequency range of the clock signal. A gear control circuit includes a regulator circuit that provides a supply voltage to the oscillator circuit. Each of the gears of the oscillator circuit corresponds to a different supply voltage provided by the regulator circuit. The regulator circuit varies the supply voltage to change a selected one of the gears of the oscillator circuit. The gear control circuit varies the supply voltage for one of the gears of the oscillator circuit to adjust a frequency range of that gear of the oscillator circuit.

Abstract: An integrated circuit die stack includes a first die having a first phase locked loop (PLL) and a second die having a second PLL. The first PLL includes a first voltage controlled oscillator (VCO) and the second PLL includes a second VCO. The first VCCO and the second VCCO share a frequency divider and a loop filter.

Abstract: A system for synchronizing a first clock and a second clock includes a receiver associated with the first clock, configured to receive a remote pulse from the second clock. The remote pulse has a pulse repetition frequency and spectral characteristics that are known to the local clock. The system also includes a local pulse emitter configured to create a local pulse at the first clock, and optics configured to align the local pulse and the remote pulse. The system further includes an interferometer configured to create an interference pattern between the local pulse and the remote pulse. A controller is provided that is configured to calculate a time delay between the first clock and the second clock based on the interference pattern between the local pulse and the remote pulse.

Abstract: A clock and data recovery circuit includes a phase detector circuit, a charge pump circuit, and a voltage controlled oscillator. The phase detector circuit receives a data signal from an external device and a clock signal from the voltage controlled oscillator and generates a first and a second phase difference signal. The charge pump circuit includes an OR gate receiving on its inputs the first and the second phase difference signals and configured to generate a current if the first and/or second phase difference signal is high.

Abstract: An apparatus comprises a clock and data recovery system, and a loss of lock detector at least partially incorporated within or otherwise associated with the clock and data recovery system. The loss of lock detector is configured to generate a loss of lock signal responsive to phase adjustment requests generated for a clock signal in the clock and data recovery system. By way of example, the loss of lock signal may have a first logic level indicative of the phase adjustment requests occurring at a first rate associated with a lock condition and a second logic level indicative of the phase adjustment requests occurring at a second rate lower than the first rate. Absolute values of respective phase increments each associated with multiple up and down phase requests may be accumulated, and the loss of lock signal generated as a function of the accumulated phase increment absolute values.

Abstract: An integrated circuit includes a first die and a second die. The first die comprising a first phase-locked loop (PLL) and the second die comprising a second PLL. The integrated circuit includes a shared loop filter, wherein the first PLL in the first die is combined with the shared loop filter to form a first PLL feedback loop, the second PLL in the second die is combined with the shared loop filter to form a second PLL feedback loop and the shared loop filter is configured to provide configurable bandwidths to each of the first PLL feedback loop and the second PLL feedback loop.

Abstract: A PLL circuit includes: a phase comparator for detecting a phase difference between a reference signal and a feedback signal; a first charge pump for outputting a current Ipr according to a detection result of the phase comparator; a second charge pump for outputting a current Iint according to the detection result of the phase comparator; a filter for outputting a current Iprop from which a high frequency component of the Ipr is removed; an integrator for integrating the Iint; a voltage-current conversion circuit for outputting a current Ivi according to an integrated result of the integrator; and an oscillator that generates an oscillating signal of a frequency according to a current Iro, a sum of the Iprop and the Ivi, and feeds it back to the phase comparator.

Abstract: A charge pump circuit is disclosed that includes a main charge pump, a replica charge pump, and an op-amp. The main charge pump includes up and down input terminals to receive UP and DN control signals, a control terminal to receive a calibration signal, and an output to generate a control voltage. The replica charge pump includes up and down input terminals to receive DN and UP control signals, a control terminal to receive the calibration signal, and an output to generate a replica voltage. The op-amp generates the calibration signal in response to the control voltage and the replica voltage.

Abstract: A reconfigurable circuit is disclosed. The reconfigurable circuit comprises a pause detector mechanism, a clock extractor, and a multiplexer. The multiplexer is configured to receive a reference clock and is coupled to the clock extractor to receive a clock extracted from a carrier of a near field communication (NFC) field. The reconfigurable circuit also comprises a phase locked loop (PLL) coupled to the pause detector mechanism and the multiplexer, and the PLL can be configured in a first mode to be locked to the reference clock, in a second mode to be locked to the extracted clock, and in a third mode wherein the PLL can switch between being locked to the reference clock and being locked to the extracted clock.

Abstract: The present disclosure provides a clock generator circuit comprising a master clock generator unit configured to generate a master clock signal, and a plurality of slave phase locked loop units. Each of the plurality of slave phase looked loop units is configured to receive the master clock signal as an input reference signal and a corresponding source clock signal. The slave phase locked loop unit may comprise an inner loop and an outer loop. The inner loop may comprise a frequency synthesizer locked on a master clock signal received from a master clock generator unit, while the outer loop may comprise a binary phase detector, an output of which goes to a loop filter with proportional and integral action, controlling the inner loop frequency value via a sigma delta input.

Abstract: A circuit comprising a loop filter, wherein the filter comprises an active integrator configured to generate one or more tuning signals, and a voltage-controlled oscillator (VCO) coupled to the loop filter and configured to generate a feedback signal based on the one or more tuning signals, wherein generating the one or more tuning signals is based on the feedback signal.

Abstract: A PLL circuit comprises a phase frequency detector (PFD), a charge pump (CP), a low pass filter (LPF), a voltage controlled oscillator (VCO), a frequency divider (FD) and a reset module. The PFD receives a first and a second input signals, and outputs a first and a second adjustment parameters according to phase and frequency difference between the first and the second input signal. The CP is coupled to the PFD, generates a current according to the first and the second adjustment parameters. The LPF is coupled to the CP, and generates a voltage according to the current. The VCO is coupled to the LPF, and generates an oscillation frequency according to the voltage. The FD receives and divides the oscillation frequency, and generates the second input signal. The reset module generates a reset signal to feed to the FD, wherein the reset module receives the first signal.

Abstract: A phase/frequency detector for controlling a charge pump includes: a core circuit arranged to output a first phase signal and a second phase signal according to a phase/frequency difference between a reference clock signal and an input clock signal; and a timing circuit coupled to the core circuit and arranged to generate a first control signal and a second control signal for controlling the charge pump according to the first phase signal and the second phase signal, wherein only one of the first control signal and the second control signal is indicative of an enabled operation when the reference clock signal and the input clock signal are substantially identical in phase.

Abstract: A system for generating a clock signal includes a phase-locked loop (PLL) and a voltage storage circuit. The PLL includes a voltage-controlled oscillator (VCO) that generates a clock signal based on a control voltage. The voltage storage circuit includes a unity-gain amplifier (UGA) and first, second and third switches. The first switch connects an input terminal of the UGA and an input of the VCO to sample the control voltage before the PLL transitions from RUN mode to STOP mode. The second switch connects the input and output terminals of the UGA to store the sampled control voltage when the PLL is in STOP mode. The third switch connects the output terminal of the UGA to the input terminal of a low pass filter (LPF) to provide the stored control voltage to the LPF when the PLL transitions from the STOP mode to the RUN mode.

Abstract: A charge pump, comprising a charge pump output may be operatively coupled to a filter input of a loop filter. A first amplifier input of an operational transconductance amplifier (OTA) may be operatively coupled to the filter input and the charge pump output, and the second amplifier input is operatively coupled to the amplifier output and filter output.

Abstract: A phase-locked loop system is provided. The system includes a charge pump, a voltage-controlled oscillator (VCO) and a bias converter. The charge pump outputs a control voltage according to a phase frequency detection signal, and generates an output current according to a bias signal. The VCO generates an output signal according to the control voltage. The bias converter is coupled between the VCO and the charge pump and for generating the bias signal according to the control voltage.

Abstract: One embodiment provides a phase-locked loop (PLL), in which a sequencer controls a loop filter such that, when a signal indicating turning-off of a power supply of the PLL is input thereto, or when a signal indicating turning-on of the power supply of the PLL is input thereto, a resistance value of a first resistance change device in the loop filter is a first resistance value, and that, after the PLL is stabilized, the resistance value of the first resistance change device is a second resistance value which is higher than the first resistance value.

Abstract: A charging/discharging circuit includes a connection terminal, a reference current providing module, an up current module and a down current module. The down current module includes: a first switch module, having a first control terminal, for receiving the down signal to determine whether the first switch module is turned on; a first bias transistor, having a first terminal coupled to the connection terminal, a second terminal coupled to the first switch module, and a control terminal coupled to the reference current providing module; and a first capacitor simulation transistor, having a first terminal and a second terminal coupled to the control terminal of the first switch module, and a control terminal coupled to the control terminal of the first bias transistor.

Abstract: It is an object of the present invention to provide a phase locked loop in which a voltage signal input to a voltage controlled oscillator after a return from a stand-by state becomes constant in a short time and power consumption is reduced. A transistor including a semiconductor layer formed using an oxide semiconductor material is provided between an input terminal of a voltage controlled oscillator and a capacitor of a loop filter. The transistor is turned on in a normal operation state and turned off in a stand-by state.

Abstract: A clock generation circuit is disclosed that may generate a plurality of phase-delayed signals in a manner that may be relatively immune to VCO pulling. The clock generation circuit may include a circuit to generate an oscillating signal, a frequency divider to generate an RF signal having a frequency that is equal to 1/(n+0.5) times the frequency of the oscillating signal, wherein n is an integer value greater than or equal to one and n+0.5 is a non-integer value, and a DLL circuit to generate a plurality of local oscillator signals, wherein the local oscillator signals are phase-delayed with respect to each other.

Abstract: In one embodiment, a circuit includes a voltage-controlled oscillator (VCO) configured to generate k first clock signals that each have a first phase based on a charge-pump control voltage signal; one or more phase interpolators (PIs) configured to receive the k first clock signals and one or more first feedback controls signals and generate m second clock signals that each have a second phase based on the k first clock signals and the one or more first feedback control signals; a first phase detector (PD) configured to receive the m second clock signals and generate the one or more first feedback control signals based on the m second clock signals; a second PD configured to generate one or more second feedback control signals based on the m second clock signals; and a charge pump configured to output the charge-pump control voltage signal based on the second feedback control signals.

Abstract: A phase locked loop circuit includes a phase frequency detector, a control circuit, a charge pump, a loop filter, a supply circuit, a ring oscillator, a frequency divider and a voltage detector. The phase frequency detector generates a frequency-increasing signal and a frequency-decreasing signal according to a phase difference between an input signal and a feedback signal. The control circuit generates a first control signal and/or a second control signal according to the frequency-increasing signal and the frequency-decreasing signal. The charge pump generates a current signal according to the first control signal and/or the second control signal. The voltage detector monitors a supply voltage of the supply circuit, and controls the control circuit to generate only the second control signal so as to reduce the supply voltage if the supply voltage is greater than a high reference voltage.

Abstract: An apparatus comprises a lock-loop circuit including an oscillator, a frequency detector, a charge pump, and a regulator. The regulator is coupled to provide a regulated signal to the oscillator to control frequency. The oscillator and the frequency detector are coupled to receive a reference clock signal. The reference clock signal is coupled to the oscillator to suppress noise in the oscillator by pulse injection. The frequency detector is coupled to receive an oscillator output from the oscillator.

Abstract: An integer-N phase-locked loop based clock generator for generating an output clock signal with a frequency N multiples of a reference clock signal, and a method for same, wherein N is a positive integer. The integer-N clock phase-locked loop based generator comprises a reference clock, a voltage controlled oscillator, a clock divider, a first and second phase generator for generating a plurality of phases of the reference clock signal and divided down output clock signal, a plurality of phase frequency detectors and charge pumps. The method comprises generating a reference clock and an output clock signals, generating a plurality of phases of a divided down output clock signal and reference clock signal, comparing the plurality of phases, and changing the frequency of the output clock signal based on the comparison.

Abstract: An edge density detector is disclosed. This edge density detector is to receive a reference frequency signal and a feedback frequency signal. This edge density detector includes a first pulse generator, a second pulse generator, and a charge pump. The first pulse generator is coupled to receive the reference frequency signal and is configured to generate a first pulse signal. The second pulse generator is coupled to receive the feedback frequency signal and is configured to generate a second pulse signal. The charge pump is coupled to receive the first pulse signal and the second pulse signal to provide a control voltage signal. The control voltage signal is a phase independent with respect to the reference frequency signal and the feedback frequency signal.

Abstract: An input jitter filter for a phase-locked loop and methods of use are provided. The method includes generating a masking zone around falling edges of a feedback signal. The method also includes determining that one or more outputs of a phase detector fall within the masking zone. The method further includes ignoring input clock noise when the one or more outputs of the phase detector fall within the masking zone.

Abstract: A filter circuit in a phase-locked loop circuit includes a capacitor coupled between a control voltage node and a first node; and a variable resistive element coupled between the first node and a ground potential. The variable resistive element has a resistance value modulated by a current proportional to the charge pump current of the charge pump. In one embodiment, the variable resistive element is a MOS transistor biased in the linear region and having a drain-to-source resistance modulated by the current proportional to the charge pump current.

Abstract: Clock generators are provided. A phase locked loop generates an output clock, a delay line is coupled to an input of the phase locked loop, and a modulation unit integrates an input signal with a constant level to generate a modulation signal controlling the delay line, thereby modulating a phase of a first input clock of the phase locked loop, such that frequency of the output clock is locked at a desired frequency.

Abstract: A phase locked loop frequency synthesizer comprises a voltage controlled oscillator; a loop filter for supplying a control voltage to the oscillator; a phase frequency detector arranged to detect a phase difference between a reference signal and a feedback signal generated from the oscillator signal and generate pulses on detector signals (UP/DN) dependent on the sign of the phase difference; and a charge pump (61) comprising current generating means and controlled switches (64, 65) arranged to convert pulses on the detector signals to current pulses from a reference voltage (Vdd?) to a common terminal (Vloop) connected to the loop filter or to current pulses from the common terminal to ground. The current generating means comprises at least one resistor (62, 63) connected between the common terminal and the switches, and the charge pump comprises an operational amplifier (66) coupled to keep the reference voltage at twice the voltage at the common terminal.

Abstract: An electronic device includes a DC-DC converter for voltage conversion in a slave mode an in a master mode and including a phase locked loop. The phase locked loop comprises a controlled oscillator, a filter having an integration capacitor coupled to a control input of the controlled oscillator, a charge pump, and a phase frequency detector. In the slave mode, the controlled oscillator, the filter, the charge pump and the phase frequency detector are coupled to operate as the phase locked loop. There is a comparator coupled with an input to a control input of the controlled oscillator and with an output to the charge pump. In the master mode, the comparator is configured to control the charge pump in response to a control signal at the control input of the controlled oscillator when the phase frequency detector is switched off so as to perform a modulation of the control signal at the control input of the controlled oscillator by charging and discharging the integration capacitor.

Abstract: A method for reducing noise in a frequency synthesizer includes selecting a design variable k, calibrating a feedback time delay (Td), such that Td=kTVCO, where TVCO is the period of the synthesizer output signal. The method further includes estimating an instantaneous quantization error to a number of bits equal to q, defining a reference bias current of Icp/(k2q), where Icp is a charge pump current signal, and applying the estimated instantaneous quantization error to a current array to produce a down modification signal (?I). The current array is biased by the reference bias current. The down modification signal (?I) is summed with the charge pump current signal Icp to modulate a down current portion of the charge pump current signal Icp.

Abstract: An electrical circuit including a controllable oscillator, a transmission line and a control loop. The controllable oscillator is configured to generate an oscillating signal. The transmission line is connected to an output of the oscillator, wherein the transmission line has a length which is a fraction of a wavelength of the oscillating signal. The control loop is configured to detect a difference between a first value of a signal parameter of the oscillating signal and a second value of the signal parameter of the oscillating signal having passed the transmission line. Furthermore, the control loop is configured to control the controllable oscillator in accordance with the difference.

Abstract: A delay locked loop operates over a wide range of frequencies and has high accuracy, small silicon area usage, low power consumption and a short lock time. The DLL combines an analog domain and a digital domain. The digital domain is responsible for initial lock and operational point stability and is frozen after the lock is reached. The analog domain is responsible for normal operation after lock is reached and provides high accuracy using smaller silicon area and low power.

Abstract: A method includes tracking a tuning voltage at a first circuit coupled to a first drain node of a first supply of a charge pump. The method also includes tracking the tuning voltage at a second circuit coupled to a second drain node of a second supply of the charge pump. The method further includes stabilizing a first voltage of the first drain node and a second voltage of the second drain node responsive to the tuning voltage.

Abstract: A method includes phase-shifting an output signal of a phase lock loop (PLL) circuit by applying an injection current to an output of a charge pump of a the PLL circuit. A circuit includes: a first phase lock loop (PLL) circuit and a second PLL circuit referenced to a same clock; a phase detector circuit that detects a phase difference between an output signal of the first PLL circuit and an output signal of the second PLL circuit; and an adjustable current source that applies an injection current to at least one of the first PLL circuit and the second PLL circuit based on an output of the phase detector circuit.