Provided is clock signal generator configured to generate a target output clock signal based on a reference clock signal, the clock signal generator includes a digital-to-time converter (DTC) configured to delay a reference clock signal based on an input code to generate a delay clock signal, and output the delay clock signal, a DTC controller configured to determine an initial gain value of the DTC based on a result of comparing at least one delay amount of the DTC with a period of a previously generated output clock signal, and generate the input code based on the initial gain value, and a phase locked loop configured to generate the target output clock signal based on the delay clock signal and a division clock signal of the previously generated output clock signal, the target output clock signal being locked to the delay clock signal.

The system includes an intermediate-frequency (IF) synthesizer that generates an IF signal based on a reference signal, and a sub-sampling PLL (SSPLL) that generates a high-frequency output signal based on an input. A switch selects either the reference signal or the IF signal to be the input to the SSPLL. When the reference signal is the input to the SSPLL, the frequency synthesizer operates in a low-noise normal-operating mode, and when the IF signal is the input to the SSPLL, the frequency synthesizer operates in a higher-noise, frequency-acquisition mode. A sub-sampling lock detector (SSLD) determines whether the frequency synthesizer becomes unlocked during the normal-operating mode, and if so, activates the switch to move the system into the frequency-acquisition mode. It also determines whether the frequency synthesizer becomes relocked to the target frequency during the frequency-acquisition mode, and if so, activates the switch to move the system into the normal-operating mode.

A system includes a digital phase-locked loop (DPLL) having a loop filter and a digitally-controlled oscillator (DCO). The system also includes a clock generator coupled to an output of the DPLL, and a plurality of clock domains coupled to the clock generator. The DPLL is configured to transition between a low power mode and a normal mode, wherein the loop filter is configured to maintain its value when the DPLL transitions from the normal mode to the low power mode. The DCO is configured to output a DCO clock signal based on the maintained loop filter value when the DPLL transitions from the low power mode to the normal mode.

A delay lock loop and a phase locking method thereof are provided. The delay lock loop includes a first divider, a delay line, a frequency multiplier, a second divider, a phase detection and controlling circuit and a setting signal generator. The first divider generates a divided reference clock signal. The second divider generates a first feedback clock signal and a second feedback clock signal which are complementary by dividing an output clock signal, and generates a selected feedback clock signal by selecting the first or second feedback clock signal according to a setting signal. The phase detection and controlling circuit compares phases of the selected feedback clock signal and the divided reference clock signal to generate a delay control signal. The setting signal generator samples the divided reference clock signal by the first feedback clock signal to generate the setting signal.

A phase locked device includes a digital controlled oscillator circuit, a clock signal generator circuitry, a time to digital converter circuit, and a logic control circuit. The digital controlled oscillator circuit is configured to generate a first clock signal in response to a plurality of digital codes. The clock signal generator circuitry is configured to generate a plurality of second clock signals according to the first clock signal, and to select a third clock signal and a fourth clock signal from the plurality of second clock signals according to a selection signal, in order to generate an output signal. The time to digital converter circuit is configured to detect a delay difference between the output signal and a reference signal, in order to generate the plurality of digital codes. The logic control circuit is configured to generate the selection signal according to the plurality of digital codes.

Disclosed is a transmitter used for a wireless charging system. The transmitter includes a plurality of phase locked loops (PLLs) that outputs single-phase power signals, a plurality of antennas that transmits power signals transmitted from the plurality of PLLs to a receiver, and a controller that determines a specific frequency for the receiver based on a signal strength indication (RSSI) received from the receiver and allows output frequencies of the plurality of PLLs to be different from each other in a specific frequency band preset based on the specific frequency.

The disclosure relates to technology for power supply for a voltage controller oscillator (VCO). A peak detector circuit determines the amplitude of the output for the VCO, which is compared to a reference value in an automatic gain control loop. An input voltage for the VCO is determined based on a difference between the reference value and the output of the peak detector circuit. The peak detector circuit can be implemented using parasitic bipolar devices in an integrated circuit formed in a CMOS process.

Disclosed is a phase-locked loop which alternately operates in a sleep state and an active state. A frequency-divided output signal of the phase-locked loop is synchronized with a frequency-divided reference signal. When the phase-locked loop switches from a sleep state to an active state, a frequency of the frequency-divided output signal is identical to a frequency of a frequency-divided output signal which has been synchronized in a previous active state. Information corresponding to the frequency of the frequency-divided output signal which has been synchronized in the previous active state is stored in a memory device.

An oscillator calibration circuit is presented. The oscillator calibration includes a first frequency locking circuit (FLC) coupled to a first oscillator, wherein the first FLC calibrates the frequency of the first oscillator using an over-the-air reference signal, wherein the first FLC calibrates the first oscillator prior to a data transmission session and remains free running during the data transmission session; and a second FLC coupled to a second oscillator, wherein the second FLC calibrates the frequency of the second oscillator using the over-the-air reference signal, wherein the second FLC calibrates the second oscillator immediately prior to a data transmission session and remains free running during the data transmission session.

A system and method for fast converging reference clock duty cycle correction for a digital to time converter (DTC) based analog fractional-N phase-locked loop (PLL) are herein disclosed. According to one embodiment, an electronic circuit includes a clock doubler, a comparator that outputs a value representing a difference between a voltage at a voltage-to-current (Gm) circuit and a reference voltage that is adjusted to compensate for an offset of the comparator, and a duty cycle calibration circuit that receives the value output from the comparator and adjusts a duty cycle of the PLL by extracting an error from the value output from the comparator and delaying a clock edge of the duty cycle according to the extracted error.