An apparatus which includes a multiphase signal generator circuit. The multiphase signal generator circuit is configured to receive as input a complementary analog signal having a fundamental frequency, and generate a plurality of output complementary analog signals. Each output complementary analog signal comprises the same fundamental frequency as the input complementary analog signal, and wherein each output complementary analog signal comprises a different phase.

A phase interpolator capable of preventing a glitch from being generated during a clock signal switching operation and a clock signal selector thereof are provided. The clock signal selector includes a selector and a selection signal generator. The selector receives multiple clock signals with different phases. The selector selects one of the clock signals according to a selection signal to generate a selected clock signal. The selection signal generator is coupled to the selector and generates the selection signal. When the selector switches from selecting a first clock signal to selecting a second clock signal as the selected clock signal, the selection signal generator generates a set time point according to a transition point of one of the first clock signal and the second clock signal whose phase lags behind a phase of the other, and generates the selection signal according to the set time point.

A delay circuit includes a first delay line suitable for delaying a first clock by a delay value that is adjusted based on a delay control code; a delay control circuit suitable for comparing a phase of the first clock delayed through the first delay line with a phase of a second clock to generate the delay control code; and a second delay line having, based on a delay control code, a delay value corresponding to a half of the delay value of the first delay line.

An optimized pulse shaping clock data recovery system is provided that includes a slicer configured to receive a signal and provide an initial set of tentative decisions to a decision feedforward equalizer, where the decision feedforward equalizer provides a fully equalized output signal. The slicer may be incorporated as part of decision feedback equalizer to provide better quality tentative decisions. The clock data recovery system also receives the first output signal that is partially equalized in such a way as to optimally shape it for a clock to sample it at an ideal location by providing an adjustment signal to the analog to digital controller.

A novel delay circuit for quadrature clock generation with insensitivity to process, voltage, temperature (PVT) variations and equal rising/falling edges is disclosed. In one implementation, the delay circuit includes a first N-substage having a sinking current source, configured to receive an input signal and to generate a rising edge of an output signal of the delay circuit, wherein the output signal is a delayed version of the input signal. The delay circuit further includes a first P-substage having a sourcing current source, configured to receive the input signal and to generate a falling edge of the output signal, where the sinking current source and the sourcing current source are variable in response to respective ones of a plurality of bias voltages.

A multiphase signal generator includes an input port. Furthermore, the multiphase signal generator includes a plurality of phase shifters. Each phase shifter of the plurality of phase shifters is configured to provide an identical phase shift Δφ. At least one phase shifter is connected to the input port. Furthermore, the multiphase signal generator includes a first phase interpolator and at least a second phase interpolator. Each phase interpolator has a respective output terminal. Each phase interpolator is configured to weight a phase of a signal at a respective first input terminal of the phase interpolator with a respective first weighting factor w.sub.i,1 and to weight a phase of another signal at a respective second input terminal of the phase interpolator with a respective second weighting factor w.sub.i,2 to generate an interpolated phase signal at the respective output terminal of the phase interpolator. A first subset of the plurality of phase shifters includes n>1 serially connected phase shifters. The first subset of phase shifters is coupled between the first input terminal and the second input terminal of the first phase interpolator. A different second subset of the plurality of phase shifters includes n serially connected phase shifters. The second subset of phase shifters is coupled between the first input terminal and the second input terminal of the second phase interpolator.

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 delay interpolator includes pull-up devices, wherein each of the pull-up devices is coupled between a supply rail and a node, and pull-down devices, wherein each of the pull-down devices is coupled between the node and a ground. The delay interpolator also includes a first control circuit coupled to the pull-up devices, wherein the first control circuit has a first input configured to receive a first signal, a second input configured to receive a second signal that is delayed with respect to the first signal, and a control input configured to receive a first delay code; and. The delay interpolator further includes a second control circuit coupled to the pull-down devices, wherein the second control circuit has a first input configured to receive the first signal, a second input configured to receive the second signal, and a control input configured to receive a second delay code.

Embodiments relate to a phase interpolator cell. The phase interpolator cell includes a multiplexer configured to select between a first pull-up network and a second pull-up network. The first pull-up network includes a first pull-up transistor controlled by a first clock signal and is connected between a first input of the multiplexer and a first power supply. The second pull-up network includes a second pull-up transistor controlled by a second clock signal and is connected between a second input of the multiplexer and the first power supply.

A delay circuit provides a programmable delay and includes an input selector circuit to select between a loop delay output signal and an input signal. A loop delay circuit provides a loop delay to the input signal and supplies the loop delay output signal. The input signal can be recirculated through the loop delay circuit to extend the range of the delay. The input selector circuit selects the feedback signal during recirculation. A variable delay circuit provides a variable delay to the loop delay output signal after the recirculation is complete and supplies a variable delay output signal. An output selector circuit selects the output of the output selector circuit during the recirculation and selects the variable delay output signal after the recirculation is complete to thereby provide a delayed signal with the delay based on the loop delay, the number of loops of recirculation, and the variable delay.