Provided are a digital phase interpolator, a clock signal generator, and a volatile memory device including the clock signal generator. The clock signal generator includes an internal signal generator configured to generate a first internal signal and a second internal signal, which mutually have a phase difference, based on an external clock signal, a first phase interpolator configured to interpolate the first internal signal with the second internal signal in response to a first control signal and generate a first interpolation signal, a second phase interpolator configured to interpolate the first internal signal with the second internal signal in response to a second control signal and generate a second interpolation signal, and a selector configured to select any one of the first interpolation signal and the second interpolation signal in response to a selection signal and output the selected interpolation signal as an internal clock signal.

A phase interpolator includes phase interpolator circuitries. The phase interpolator circuitries generate an output clock signal from an output node according to phase control bits and clock signals. Phases of the clock signals are different from each other. Each phase circuitry includes phase buffer circuits. Each phase buffer circuit is turned on according a first bit and a second bit of the phase control bits, in order to generate a signal component in the output clock signal according to a corresponding clock signal of the clock signals. Each phase buffer circuit includes a first resistor and a second resistor, and transmits one of a first voltage and a second voltage to the output node according to the corresponding clock signal, in which the first voltage is transmitted to the output node via the first resistor, and the second voltage is transmitted to the output node via the second resistor.

A system includes a sampler, a receiver phase-locked loop circuit configured to provide one or more input clock signals, and a phase interpolation circuit coupled to the receiver phase-locked loop circuit and the sampler. The phase interpolation circuit further includes a first phase interpolator configured to generate a first recovered clock signal based on the one or more input clock signals and a first code, and a second phase interpolator configured to generate a second recovered clock signal based on the one or more input clock signals and a second code, wherein the second code has an interpolation code offset from the first code, wherein the interpolation code offset corresponds to a phase shift in the second recovered clock signal relative to the first recovered clock signal, wherein the outputs of the first phase interpolator and second phase interpolator are configured to be merged.

A fractional sampling-rate converter includes a first-in first-out (FIFO) buffer, a write logic, a read logic and a fractional interpolator. The write logic is designed to write input data samples into the FIFO at a first rate. The fractional interpolator is coupled to receive the input data samples from the FIFO and is designed to generate corresponding interpolated data samples as an output of the fractional sampling-rate converter at a second rate. The read logic is designed to cause input data samples in the FIFO buffer to be transferred to the fractional interpolator. A ratio of the second rate and the first rate is a fractional number greater than one.

There is provided an optical encoder including a phase shifter circuit, two multiplexers, two digital circuits and four comparators. The phase shifter circuit receives signals from an amplifier and outputs multiple phase shifted signals. Each of the two multiplexers receives a half of the multiple phase shifted signals and outputs two pairs of phase shifted signals, each pair having 180 degrees phase difference, respectively to two comparators connected thereto. Each of the two digital circuits controls the corresponding multiplexer to select the two pairs of phase shifted signals from the half of the multiple phase shifted signals.

There is provided an optical encoder including a phase shifter circuit, two multiplexers, two digital circuits and four comparators. The phase shifter circuit receives signals from an amplifier and outputs multiple phase shifted signals. Each of the two multiplexers receives a half of the multiple phase shifted signals and outputs two pairs of phase shifted signals, each pair having 180 degrees phase difference, respectively to two comparators connected thereto. Each of the two digital circuits controls the corresponding multiplexer to select the two pairs of phase shifted signals from the half of the multiple phase shifted signals.

A phase interpolating (PI) system includes: a PI stage configured to receive first and second clock signals and a multi-bit weighting signal, and generate an interpolated clock signal; and an amplifying stage configured to receive and amplify the interpolated clock signal, the amplifying stage including a capacitive component. The capacitive component is tunable to exhibit non-zero capacitances. The capacitive component has a Miller effect configuration resulting in a reduced footprint of the amplifying stage.

A clock and data recovery circuit includes a phase detector that outputs phase characteristic data based on a digital data signal and an adjustment circuit that adjusts phase characteristic data. The clock and data recovery circuit sets an adjustment value in an adjustment circuit by calculating an adjustment value of phase characteristic data using a monitor circuit while changing a phase of a reference clock signal to be adjusted in a phase interpolation circuit based on offset data output from an offset output circuit in a training period before communication starts.

Embodiments relate to a circuit implementation for controlling a delay of a clock signal. The clock delay control circuit includes a sensing circuit and a phase interpolator controlled by the sensing circuit. The sensing circuit generates a first control signal that increases when a level of a supply voltage increases, and decreases when the level of the supply voltage decreases. Moreover, the sensing circuit generates a second control signal that decreases when the level of the supply voltage increases, and increases when the level of the supply voltage decreases. The phase interpolator includes multiple paths, each having a different propagation delay. The coupling between each path and the output node of the phase interpolator is controlled by the control signals generated by the sensing circuit.

A phase interpolating (PI) system includes: a phase-interpolating (PI) stage configured to receive first and second clock signals and a multi-bit weighting signal, and generate an interpolated clock signal, the PI stage being further configured to avoid a pull-up/pull-down (PUPD) short-circuit situation by using the multi-bit weighting signal and a logical inverse thereof (multi-bit weighting_bar signal); and an amplifying stage configured to receive and amplify the interpolated clock signal, the amplifying stage including a capacitive component; the capacitive component being tunable; and the capacitive component having a Miller effect configuration resulting in a reduced footprint of the amplifying stage.