A phase synchronization circuit includes: an oscillation circuit that includes a variable current generation unit that generates a variable current of a current amount corresponding to a control voltage and a fixed current generation unit that generates a fixed. current of a current amount corresponding to a correction code and generates an output clock signal having a frequency corresponding to the total current amount of the variable current and the fixed current; a feedback circuit that generates a feedback clock signal based on the output clock signal; a control voltage generation circuit that generates the control voltage to make a frequency of the output clock signal become a desired frequency in a normal operation mode; and a correction code generation circuit that generates the correction code in a calibration mode, in which in the calibration mode, the control voltage generation circuit outputs a fixed one of the control voltage.

A phase synchronization circuit includes: an oscillation circuit that includes a variable current generation unit that generates a variable current of a current amount corresponding to a control voltage and a fixed current generation unit that generates a fixed. current of a current amount corresponding to a correction code and generates an output clock signal having a frequency corresponding to the total current amount of the variable current and the fixed current; a feedback circuit that generates a feedback clock signal based on the output clock signal; a control voltage generation circuit that generates the control voltage to make a frequency of the output clock signal become a desired frequency in a normal operation mode; and a correction code generation circuit that generates the correction code in a calibration mode, in which in the calibration mode, the control voltage generation circuit outputs a fixed one of the control voltage.

The present disclosure discloses a digital loop filter in an all-digital phase-locked loop. The digital loop filter may include a selection circuit configured to output one of a first data signal and a second data signal as valid data, a first operation circuit configured to output a first operation signal by adding or subtracting the valid data and a first register signal, a first register circuit configured to register the first operation signal and output the first operation signal as the first register signal, a second operation circuit configured to output a second operation signal by adding or subtracting a value of at least one bit of the valid data and the first register signal, and a second register circuit configured to store the second operation signal and output the second operation signal as a control signal.

The present disclosure discloses a digital loop filter in an all-digital phase-locked loop. The digital loop filter may include a selection circuit configured to output one of a first data signal and a second data signal as valid data, a first operation circuit configured to output a first operation signal by adding or subtracting the valid data and a first register signal, a first register circuit configured to register the first operation signal and output the first operation signal as the first register signal, a second operation circuit configured to output a second operation signal by adding or subtracting a value of at least one bit of the valid data and the first register signal, and a second register circuit configured to store the second operation signal and output the second operation signal as a control signal.

A dual-loop phase-locking circuit combines a conventional phase-frequency-detector (PFD) and frequency-divider based first loop to lock an output signal frequency to a multiple of a reference signal frequency within a first loop bandwidth BW1 with a second loop to simultaneously lock the output signal phase to a second signal independently locked to the same multiple of the reference signal. The second loop integrates the phase error between the output signal and the second signal, and applies an offset at the PFD output in the first loop to reduce the first loop phase errors within a second loop bandwidth BW2 (<BW1). The first loop bandwidth BW1 can be optimized for overall phase-noise performance of the output signal while retaining the excellent capture and hold characteristics of that loop's topology. The second loop provides superior carrier-frequency phase alignment between the output signal and second signal. The output and second signal may therefore be configured as inputs to systems that require highly coherent carrier signals with de-correlated phase-noise such as phase-noise measurement systems or phase-noise cancellation systems.

A dual-loop phase-locking circuit combines a conventional phase-frequency-detector (PFD) and frequency-divider based first loop to lock an output signal frequency to a multiple of a reference signal frequency within a first loop bandwidth BW1 with a second loop to simultaneously lock the output signal phase to a second signal independently locked to the same multiple of the reference signal. The second loop integrates the phase error between the output signal and the second signal, and applies an offset at the PFD output in the first loop to reduce the first loop phase errors within a second loop bandwidth BW2 (<BW1). The first loop bandwidth BW1 can be optimized for overall phase-noise performance of the output signal while retaining the excellent capture and hold characteristics of that loop's topology. The second loop provides superior carrier-frequency phase alignment between the output signal and second signal. The output and second signal may therefore be configured as inputs to systems that require highly coherent carrier signals with de-correlated phase-noise such as phase-noise measurement systems or phase-noise cancellation systems.

An all-digital phase-locked loop (ADPLL) and a calibration method thereof are provided. The ADPLL includes a digitally controlled oscillator (DCO), a time-to-digital converter (TDC) coupled to the DCO, and a normalization circuit coupled to the TDC. The DCO is configured to generate a clock signal according to a frequency control signal. The TDC is configured to generate a digital output signal according to a phase error between the clock signal and a reference signal. The normalization circuit is configured to convert the digital output signal into a clock phase value according to a gain parameter. More particularly, the normalization circuit may modify the gain parameter according to a phase error value between the clock phase value and a reference phase value.

A phase locked loop includes a phase detector outputting a first signal corresponding to a phase difference of a reference frequency signal and a division frequency signal, a charge pump amplifying a first signal to output a second signal, a loop filter filtering the second signal to output a third signal, a voltage-to-current converter receiving the third signal and outputting a fourth signal, a digital-to-analog converter outputting a fifth signal based on the fourth signal and a digital compensation signal, an oscillator outputting an output frequency signal having a frequency corresponding to the fifth signal, a divider dividing the frequency of the output frequency signal to output the division frequency signal and a compensation frequency signal, and an automatic frequency calibrator compensating for the voltage-to-current converter based on a difference between a frequency of the compensation frequency signal and a frequency of a reference frequency signal.

Described is a high Q-factor inductor. The inductor is formed as a unit cell coil, which is copied twice for a dual-coil inductor and copied four times for a quad-coil inductor. For each copy of the unit cell coil, the coil is rotated a subsequent substantially 90 degrees or substantially −90 degrees. The rotation enables the terminals of the inductor to be routed equal-distant to a circuit that is placed in the line of symmetry between the two coils.

Described is a high Q-factor inductor. The inductor is formed as a unit cell coil, which is copied twice for a dual-coil inductor and copied four times for a quad-coil inductor. For each copy of the unit cell coil, the coil is rotated a subsequent substantially 90 degrees or substantially −90 degrees. The rotation enables the terminals of the inductor to be routed equal-distant to a circuit that is placed in the line of symmetry between the two coils.