162 results about "Frequency synthesizer" patented technology

The invention provides a programmable frequency control array radar waveform generation system and method based on an FPGA, and belongs to the technical field of radar systems and digital signal processing. In order to solve the technical problems of complex hardware system, inflexible parameter adjustment and poor multi-channel synchronism of the traditional frequency control array radar, the invention provides an integrated high-performance solution. The system adopts an FPGA (Field Programmable Gate Array) architecture of an integrated processing system (PS) and programmable logic (PL). The method comprises the following steps: a PS end receives waveform control parameters of an upper computer through a communication interface and transmits the waveform control parameters to a PL end; and a plurality of parallel direct digital frequency synthesizer (DDS) modules in the PL end synchronously generate multi-channel digital baseband signals with programmable frequency offset at high precision according to the parameters under the unified driving of the FPGA global clock network. And the digital signal is subjected to digital-to-analog conversion and radio frequency front-end processing to finally form a transmitting wave beam. According to the invention, flexible programmability of parameters is realized by utilizing a PS-PL collaborative architecture, the synchronization precision of multi-channel signals is remarkably improved through a global clock network and a parallel DDS module generated in the FPGA, and meanwhile, the system has the advantages of high integration level and low complexity.

The invention discloses a fractional frequency division frequency synthesizer with output signal phase synchronization and frequency modulation continuous wave functions, and the basic structure is a charge pump phase-locked loop. Comprising a phase frequency detector, a first charge pump, a second charge pump, a low-pass filter, a voltage-controlled oscillator, a first buffer, a second buffer, a two-frequency divider chain, an IQ undersampling circuit, a local oscillator generator, a programmable multimode frequency divider, a Delta-Sigma modulator (DSM), a first selector, a second selector, a third selector, a tracking phase accumulator, a numerical control oscillator, an accumulation phase difference register and an atan2 logic circuit. The device comprises a main phase control circuit, a phase adjusting circuit, an enabling control circuit, a waveform generator and a serial peripheral interface. The decimal frequency-division frequency synthesizer can be applied to a general-inductance integrated system, ensures that output signals provided by a plurality of decimal frequency-division frequency synthesizers are consistent in phase in a multi-channel radio frequency transceiving system adopting a multi-chip splicing mode, and can also be applied to the general-inductance integrated system as a sensing signal source; and the speed and the distance of an object can be quickly sensed by the high linearity and the quick chirp capability of an output signal. The decimal frequency division frequency synthesizer is applied to a linear frequency modulation continuous wave radar system, initial phase synchronization can be carried out firstly, then frequency continuous modulation is carried out, and measurement errors can be eliminated. In view of functional similarity of partial modules of the synchronous loop and the FMCW loop, such as a phase frequency detector, a charge pump, a voltage-controlled oscillator and the like, the modules can be shared, so that the power consumption and area cost of the system are remarkably reduced.

The invention discloses a deformation rolling stone integrated road slope radar monitoring system and a detection method, and belongs to the field of radar detection, the deformation rolling stone integrated road slope radar monitoring system comprises a signal processing module, a multi-channel radio frequency module and an antenna array module, the multi-channel radio frequency module is connected with the signal processing module through a hardware line, and the antenna array module is connected with the signal processing module. The antenna array module is connected with the multi-channel radio frequency module through a hardware line; the signal processing module comprises a programmable main control chip, a data memory, an analog-to-digital converter and a direct digital frequency synthesizer, a line of the signal processing module is also connected with a camera, and the system also comprises a power supply module for supplying power to the signal processing module, the multi-channel radio frequency module and the camera. According to the deformation and rolling stone integrated road slope radar monitoring system and the detection method, deformation and rolling stone integrated monitoring is realized, two sets of equipment do not need to be arranged, the cost and the arrangement difficulty are reduced, early warning is reliable, the environmental adaptability is high, and the requirement for long-term field road monitoring is met.

The invention relates to the technical field of signal generation, and discloses a signal generation system and method, and the system comprises a first signal generation module; the second signal generation module comprises an analog signal generation unit and a signal copying unit; the signal mixing module comprises an analog frequency mixing unit, a digital frequency mixing unit and a signal switching unit; the output end of the analog signal generation unit is connected with the input end of the analog frequency mixing unit; the first end of the signal copying unit is connected with the clock signal output end of the analog signal generating unit, the second end is connected with the mixing input end of the analog signal generating unit, and the third end is connected with the first end of the signal switching unit; the second end of the signal switching unit is connected with the output end of the analog frequency mixing unit, and the third end is connected with the input end of the digital frequency mixing unit. Therefore, a direct digital frequency synthesizer in the analog signal generation unit is calibrated when the clock signal is switched to, and spurious signals are eliminated based on a calibration result when the clock signal is switched to the analog local oscillator signal.

The invention discloses an online cable fault detection device and calibration method based on broadband impedance spectroscopy, belongs to the technical field of cable fault detection, is used for cable fault detection, and comprises a direct digital frequency synthesizer DDS, a micro control unit MCU, an analog-to-digital converter ADC, four low-pass filters, two multipliers and an electromagnetic coupling device. The DDS is respectively connected with the MCU, the first low-pass filter and the second low-pass filter, and the analog-to-digital converter ADC is respectively connected with the MCU, the third low-pass filter and the fourth low-pass filter; the calibration process of the method includes obtaining a measured value of the cable reflection coefficient and a true value of the cable reflection coefficient. According to the invention, cable defects are monitored and positioning is realized during on-line operation of the cable, and the method is suitable for cables of various specifications and three-phase cables, has universality, and reduces the detection difficulty; the broadband impedance spectroscopy measurement precision is improved, the measurement error is reduced, and the cable fault defect positioning precision is improved.

The invention discloses a phased array radar and a low-altitude detection radar system, the phased array radar comprises a lower shell and an upper shell which are oppositely arranged in a first direction, the lower shell and the upper shell define a containing cavity, and the containing cavity comprises a first cavity located in the lower shell; the phased array radar further comprises a frequency synthesizer, a signal processing plate, a heat conduction plate, an air cooling mechanism, a plurality of TR assemblies, an antenna and an antenna housing. The frequency synthesizer is arranged in the first cavity. The signal processing plate is arranged in the first cavity and is compactly arranged with the frequency synthesizer in the second direction; the heat conducting plate is arranged in the first cavity and located on the side, facing the upper shell, of the signal processing plate, the heat conducting plate is attached to the frequency synthesizer and the signal processing plate, and a cooling pipe is embedded in the heat conducting plate; the air cooling mechanism is arranged in the containing cavity and used for supplying air to the heat conduction plate so as to cool the heat conduction plate. The antenna housing is arranged on the side, away from the lower shell, of the upper shell so as to cover the TR assembly and the antenna. Through the compact arrangement of the frequency synthesizer and the signal processing board, the size of the phased array radar can be greatly reduced, and the phased array radar is convenient to carry and deploy.

The utility model discloses interference source equipment. Comprising a power control subsystem for realizing signal receiving and transmitting and power dynamic management, an intermediate frequency signal processing subsystem for realizing high-speed signal acquisition and playback, a main control subsystem for realizing system control, man-machine interaction and data processing, and an air feed subsystem for realizing radiation and receiving of electromagnetic signals, the power control subsystem comprises a signal receiving module used for receiving and transmitting communication signals, a transmitting channel module and a frequency synthesizer module, and the frequency synthesizer module integrates a voltage-controlled constant-temperature crystal oscillator, provides stable clock signals and simultaneously comprises external reference clock access and Beidou time synchronization; through integration of the power control subsystem, the intermediate frequency signal processing subsystem, the main control subsystem and the air feed subsystem, the volume and the weight are reduced, an individual soldier is convenient to carry, and the strategic significance of the utility model is increased.

The present disclosure provides an apparatus for wireless communications. The apparatus includes one or more processors; a transmit path coupled to the one or more processors comprising: a first frequency synthesizer configured to consume a first amount of power, wherein the first frequency synthesizer is configured to feed a first local oscillator (LO) signal that comprises a first frequency tone with a first phase noise profile; and a feedback receive path selectively coupled to the transmit path comprising: a second frequency synthesizer configured to consume a second amount of power less than the first amount of power, wherein: the second frequency synthesizer is configured to feed a second LO signal that comprises a second frequency tone with a second phase noise profile; the second frequency tone is offset from the first frequency tone; and the second phase noise profile comprises a wider phase profile than the first phase noise profile.

This invention discloses a multi-level collaborative SAW exhaled breath detection system and method based on a large language model, belonging to the field of SAW detection technology. The system includes a precision RF excitation control layer, an IoT gateway layer, and a cloud-based AI analysis layer. Data interaction between the three layers is achieved through a heterogeneous communication protocol stack. The precision RF excitation control layer includes a microcontroller, a DDS frequency synthesizer, and an SAW resonator; the microcontroller has a built-in pre-verification module. The IoT gateway layer includes a dual-core processor, a wireless communication module, and an I / O interface. 2 The system features an S-channel audio interface and a dual-core processor with a heterogeneous architecture. The cloud-based AI analysis layer includes speech recognition services, large language model inference services, a utility function definition library submodule, and a command string generation submodule. The system has an end-to-end device-level mapping channel from user speech to the DDS frequency synthesizer's frequency tuning word register. This invention lowers the operational threshold for precision SAW inspection and adapts to on-site inspection scenarios.

The application discloses a microwave photon frequency hopping signal generation device and method based on an optical switch and belongs to the technical field of optical communication. The application is composed of a light source, a beam splitter, an optical frequency comb generator, an electro-optical frequency shifter, an acousto-optic modulator, a digital frequency synthesizer, a filter array, a signal control unit, an electrically controlled high-speed optical switch, a beam combiner and a photoelectric detector. The application separates optical frequency comb teeth by using an ultra-narrow bandwidth optical filter, selects and opens the frequency hopping signal generated by the local light beat frequency through the optical switch, and can generate a high-speed high-order high-stability frequency hopping signal compared with the prior art.

The present application relates to a frequency synthesizer with dynamically selected level shifting of an oscillating output signal. An oscillator circuit powered by a source voltage generates an oscillating output signal. The oscillating output signal is level shifted and applied to a first input of a multiplexer. A second input of the multiplexer receives the oscillating output signal. The multiplexer selects one of the oscillating output signal and the level shifted oscillating output signal to output as a selected oscillating output signal in response to a selection signal. A lock loop circuit controls a frequency of the oscillating output signal based on the selected oscillating output signal and a reference oscillating signal. The selection signal also selects one of the source voltage of the oscillator circuit and a reference voltage as an error amplifier reference voltage for a voltage regulator circuit that generates a first supply voltage.

The invention discloses an anti-interference radio frequency transceiving assembly which comprises a plurality of B1 low-noise amplification units, a B1 array antenna, a plurality of B3 low-noise amplification units, a B3 down-converter, a BDS B1 / GPS L1 down-converter, a first frequency synthesizer, a second frequency synthesizer, a crosslinking equipment digital signal processing board, a BDS B1 / GPS L1 up-converter, a B3 up-converter, a B2B low-noise amplifier unit and an S low-noise amplification unit. And the first triplexer is in data connection with the L power amplifier unit, the B2B, S and L three-in-one antenna array, the first directional coupler and the first logarithmic detector. According to the invention, electromagnetic wave signals of multiple paths of B3 and multiple paths of BDS B1 / GPS L1 are converted into electric signals, and the signals are filtered and amplified, so that amplitude-phase consistency is satisfied. And performing up-conversion on the analog intermediate frequency signal processed by the cross-linked digital signal processing board to output BDS B3 and BDS B1 / GPS L1 radio frequency signals. And the short message integrated service digital network can be realized.

The invention provides a design method of an ultra-low phase noise frequency synthesizer based on regenerative frequency division. The design method comprises the following steps: step 1, enabling a source frequency to generate a multiple frequency through a frequency multiplier; step 2, inputting the multiple frequency into a two-way power divider, and generating an excessive frequency 1 through a phase-locked loop 1 by one path of output of the two-way power divider; the other path of output of the two-way power divider generates an excessive frequency 2 through a phase-locked loop 2; 3, the transition frequency 1 passes through a digital frequency divider and a regeneration frequency divider in sequence to generate transition frequency 3; and step 4, inputting the transition frequency 2 and the transition frequency 3 into a frequency mixer for frequency mixing, and then processing through a filter and an amplifier again to generate a target frequency. When the circuit topology and the transition frequency are designed, how to reduce the phase noise index is considered. According to the design method, the low-phase noise characteristic of the regenerative frequency divider is fully utilized.

The invention belongs to the technical field of radars, and relates to a complete polarization continuous wave rain detection radar system and method, and the system is fixedly installed on the ground and comprises a two-dimensional servo turntable, a transmitting and receiving antenna and a processing case. The transmitting antenna and the receiving antenna are respectively arranged on two sides of the two-dimensional servo turntable and carry out azimuth rotation and pitch angle adjustment along with the two-dimensional servo turntable. The transmitting antenna simultaneously transmits horizontal / vertical polarization signals, and the receiving antenna simultaneously receives dual-polarization echo signals. In the processing case, a transmitting assembly is connected with a transmitting antenna, and the excitation signal is radiated through the transmitting antenna after being amplified; the receiving component is connected with a receiving antenna and is used for performing low-noise amplification, down-conversion and the like on the echo signal; the frequency synthesizer board card generates a linear frequency modulation continuous wave excitation signal; the acquisition processing board card carries out AD sampling, pulse compression, clutter suppression, echo parameter estimation and other processing on the echo signal so as to realize raindrop characteristic analysis.

The present application relates to a kind of complex waveform generating device of anti-active jamming, belong to radar detection guidance and electronic countermeasure technical field, solve the problem that the existing radar main signal is higher in the probability of being detected and intercepted by jammer.One kind of complex waveform generating device of anti-active jamming, including control unit, direct digital frequency synthesizer and signal output unit, the control unit is connected with signal output unit by direct digital frequency synthesizer.The complex waveform generating device of anti-active jamming of the present application, the complex waveform main signal of emission and cover signal random arrangement, cover signal generation time, pulse width, signal bandwidth, emission frequency point, frequency modulation slope and signal number are random, difficult to predict.The signal output by complex waveform generating device is more difficult to distinguish, greatly reduce the probability of main signal interception and the difficulty of correct implementation of jammer, increase the means and strategy of anti-jamming, improve the performance of radar anti-jamming and radar tracking stability.

In one example, the system includes a phase-locked loop (100) comprising a charge pump (104) coupled to a phase frequency detector (102), a low-pass filter (106) coupled to the charge pump, and a VCO (108) coupled to the low-pass filter, wherein the charge pump is configured to provide a charge pump current (126) to the low-pass filter. The system also includes a current source (114) configured to provide a bias current (130) to the charge pump. The system includes a first bias compensation circuit (116) configured to increase the bias current (130) in response to a control voltage (128) supplied to the VCO being within a first range. The system also includes a second bias compensation circuit (116) configured to decrease the bias current (130) in response to a control voltage (128) supplied to the VCO being within a second range.

A frequency synthesizer includes a voltage controlled oscillator, an analog-to-digital converter, a first processing unit and a second processing unit, an adder, a digital-to-analog converter, a monitoring unit, and a switching unit. The first processing unit and a second processing unit output a first digital signal and a second digital signal for frequency adjustment corresponding to a phase difference, respectively. The adder outputs an addition signal obtained by adding the output from the first processing unit to the output from the second processing unit to a downstream stage. The switching unit switches a first state in which only the first digital signal among the first digital signal and the second digital signal is supplied to the adder to a second state in which the second digital signal and the first digital signal as a fixed value are each supplied to the adder, based on a parameter.

The invention relates to an electric control phase shifting device for quantum homodyne detection and a phase shifting regulation and control method of the electric control phase shifting device. The electric control phase shifting device comprises a first beam splitting piece, a first interference arm, a second interference arm and a second beam splitting piece. After input signal light to be measured is split into two beams of signal light through a first beam splitting piece, one beam of signal light passes through a first interference arm to obtain signal light subjected to phase shift / frequency shift, and the other beam of signal light passes through a second interference arm to obtain signal light not subjected to phase shift / frequency shift; the signal light subjected to phase shift / frequency shift and the signal light not subjected to phase shift / frequency shift are respectively input into a second beam splitter and then are divided into two paths to be output; the optical phase shift of the electric control phase shifter is adjusted by adjusting and changing the frequency difference delta fs generated by the first interference arm to the signal light; by means of the characteristic that the frequency shift amount of the acousto-optic crystal is controlled by the driving frequency and in combination with the fine frequency adjustment capability of the digital frequency synthesizer, high-precision frequency control over the optical phase shift amount is achieved.

This invention discloses a phase-amplitude conversion method and apparatus for a direct digital frequency synthesizer. The method includes the following steps: receiving an input phase word; performing trigone normalization on a subdivided phase field based on a trigone control field in the input phase word; using the first field of the normalized subdivided phase field as an index to look up a table, retrieving the initial sine and initial cosine values ​​corresponding to the index from a preset lookup table to obtain a coarse rotation result; generating a rotation code based on the second field of the normalized subdivided phase field; performing rotation correction on the coarse rotation result based on the rotation code to obtain a fine rotation result; and restoring the trigone control field to the final fine rotation result to obtain the final sine and cosine amplitude values. This invention can meet the high-precision requirements of phase-amplitude conversion while reducing storage requirements.

A front-end synchronous control method for cooperative detection of multi-base phased array radars comprises the steps that hardware comprises an atomic clock, a Beidou / GPS receiving assembly and a clock source or a frequency synthesizer, it is ensured that the atomic clock and the Beidou / GPS receiving assembly are arranged outside each radar system of the same model, a reference clock source or a frequency synthesizer capable of being synchronized by the external atomic clock is arranged inside each radar system of the same model, and software is FPGA software. The method comprises the following five steps: taking a high-precision time source and a high-stability clock source as references; a time extrapolation processing module, a time comprehensive processing module, a time sequence awakening / silence module, a time sequence generating and issuing module and a control signal coding and issuing module which run FPGA software in the time sequence generating equipment comprehensively process and generate synchronous time sequence square wave signals and time sequence serial control signals; the synchronization of front-end clocks or excitation signals of a plurality of radar array surfaces and the synchronization of time sequence transmitting and receiving signals are realized, so that all simulation T / R assemblies of a plurality of radars of the same model are in a synchronous transmitting and receiving state, and the front-end synchronization target of cooperative detection is achieved.

This application relates to the field of satellite positioning technology, and provides a satellite signal receiving circuit, a satellite signal processing circuit, and a dual-frequency receiver. The satellite signal receiving circuit includes: a first RF input port connected to a first terminal of a first mixer via a first low-noise amplifier; a second terminal of the first mixer connected to a first RF signal output terminal via a first low-pass filter; a second RF input port connected to a first terminal of a second mixer via a second low-noise amplifier; a second terminal of the second mixer connected to a second RF signal output terminal via a second low-pass filter; and a third terminal of the first mixer connected to a third terminal of the second mixer via a frequency synthesizer. This improves the flexibility of switching RF input ports in the satellite signal processing circuit of the dual-frequency receiver.

In an embodiment, a frequency synthesizer includes a digitally controlled oscillator configured to generate an output clock signal based on a digital control word, a clock divider configured to divide the output clock signal to generate a divided clock signal, a digital-to-time converter configured to generate a feedback clock signal based on the divided clock signal, a time-to-digital converter configured to generate a phase error signal based on a bias control word and a phase difference between a reference clock signal and the feedback clock signal, a loop filter connected to the time-to-digital converter and configured to generate the digital control word based on the phase error signal, and a calibration unit configured to generate a training sequence to generate a gain error signal, and modify the bias control word based on the gain error signal to generate a modified bias control word.

A technique for reducing the effects of charge injection when a charge pump in a fractional-N frequency synthesizer switches from an error cancellation phase of error current generation to a full-scale phase of error current generation uses a dummy digital-to-analog converter to steer excess current from the error cancellation phase to a voltage regulated node. As a result, the voltage swing of an inactive branch of a digital-to-analog converter of the charge pump is the same as the voltage swing of the active branch of the charge pump, i.e., the device overlap capacitance charge injection is in phase for the branches of a digital-to-analog converter in the charge pump.

A method of measuring phase noise (PN). A PLL frequency synthesizer is provided including a first phase frequency detector (PFD) receiving a reference frequency signal coupled to a first charge pump (CP) coupled to a VCO having an output fedback to the first PFD through a feedback divider that provides a divided frequency signal to the first PFD which outputs an error signal, and PN measurement circuitry including a replica CP coupled to an output of a second PFD or the first PFD. The error signal is received at the replica CP or the divided and reference frequency signal are received at the second PFD, wherein the replica CP outputs a scaled phase error current which is current-to-voltage converted and amplified to provide an amplified phase error voltage, and digitized to provide a digital phase error signal. The digital phase error signal is frequency analyzed to generate a PN measurement.

The invention particularly relates to a method for generating high-power microwave beat waves, a transmitting array plane of a phased array high-power microwave system is divided into two or more sub-array planes capable of working independently, each sub-array plane is provided with an independent feed network and frequency synthesizers, and the multiple frequency synthesizers can achieve time alignment through synchronizing signals. And microwave excitation signals with the same or different carrier frequencies can be generated. The plurality of frequency synthesizers output different carrier frequency pulses, each independent subarray surface amplifies signals and radiates the signals outwards, and high-power beat wave pulses can be formed through space synthesis. The types of radiation pulse waveforms of the phased array high-power microwave system are increased, the strike distance of the high-power microwave system is increased, the universality of a killing target is improved, and the method has the advantages that the beat wave generation method is easy to implement, and the pulse waveforms are flexible and changeable.

A fractional frequency synthesizer, a fractional PLL, and a method for generating a fractional frequency signal based on a reference signal are provided. An example fractional frequency synthesizer includes a multi-phase clock generator configured to generate a clock vector comprising a plurality of clock signals, each oscillating according to a fractional frequency in relation to the reference frequency and each clock signal offset by a phase offset. The fractional frequency synthesizer includes multi-phase divider circuitry configured to select a clock signal from the clock vector to generate a fractional frequency feedback signal. An accumulator configured to increment a count and a rollover detector configured to determine a rollover value associated with a rollover event on the accumulator are further included. A clock signal is selected based on the rollover value and the fractional frequency feedback signal is generated based at least in part on the selected clock signal.

A frequency synthesizer is disclosed which comprises a fractional- N synthesizer configured to provide a synthesized frequency signal based on a first reference frequency signal while controlled based on a second or third reference frequency signal, wherein the first reference frequency signal has higher frequency than the second and third reference frequency signals. The frequency synthesizer also comprises a first frequency divider configured to provide a first divided frequency signal based on the synthesized frequency signal while controlled by a first divider ratio, first phase difference circuitry configured to determine a first phase difference between the first divided frequency signal and the third reference frequency signal, wherein the first divider ratio is determined based on the first phase difference, and switching circuitry configured to cause the fractional-N synthesizer to be controlled based on the third reference frequency signal responsive to loss of the second reference frequency signal. Corresponding circuitry arrangement, integrated circuit, and electronic apparatus are also disclosed.

The invention discloses a full-scale deep sea dissolved CH4 in-situ sensor, and belongs to the technical field of deep sea dissolved gas in-situ detection, and the full-scale deep sea dissolved CH4 in-situ sensor comprises a circuit system unit, a trace gas measurement cavity unit and a water-gas separation unit; the circuit system unit comprises a microcontroller, a frequency synthesizer, a summator, a laser, a laser driving circuit, two analog lock-in amplifiers, two pre-amplifiers and two analog-to-digital converters; the trace gas measuring cavity unit comprises a trace gas measuring cavity, an optical fiber collimator, a tuning fork, a coaxial micro resonant tube, a temperature, humidity and air pressure sensor, a photoelectric detector, two electromagnetic valves and a micro air pump; the water-gas separation unit comprises a base, a sintered block, filter paper and a water-gas separation membrane; the miniaturized deep sea dissolved CH4 high-sensitivity full-range in-situ sensor with low gas consumption has the advantages of high sensitivity, full range, low gas consumption, strong anti-interference capability, fast response, low power consumption, small size and the like.

To enable an increase in repetition rates of a passively mode-locked laser by a factor of up to 1000 up to a frequency range of 1 to 40GHz while maintaining comb characteristics of a harmonically mode-locked (HML) frequency comb laser.SOLUTION: The HML laser may include a reference cavity having a beam splitter that is common mode to the reference cavity and the main cavity, and is further configured to generate an output for the HML optical frequency comb. The bulk as well as the fiber reference cavities can be implemented with ultra-low expansion thermal expansion materials that enable the use of HML lasers as precision frequency references and frequency synthesizers for the microwave, millimeter wave, and optical frequency domains. HML dual-frequency combs with minimal differential noise between the two combs can reference both combs to the same reference cavity.SELECTED DRAWING: Figure 2A

In one embodiment, a frequency synthesizer comprises a digitally controlled oscillator configured to generate an output clock signal based on a digital control word, a clock divider configured to split the output clock signal to generate a split clock signal, a digital-to-digital converter configured to generate a feedback clock signal based on the split clock signal, a time-to-digital converter configured to generate a phase error signal based on a bias control word and a phase difference between a reference clock signal and the feedback clock signal, a loop filter connected to the time-to-digital converter configured to generate the digital control word based on the phase error signal, and a calibration unit configured to generate a training sequence to produce a gain error signal.and to modify the bias control word based on the gain error signal to create a modified bias control word.