Systems and methods for adaptively adjusting a slew rate of a dejitter buffer in a remote device in a distributed access architecture. The slew rate may be adjusted based on measurements of a fullness state of a buffer made over time. The measurements may be used to calculate a frequency offset value between the rate at which data leaves the buffer relative to the rate at which data enters the buffer and/or used to calculate a current working depth of the buffer. The adaptive slew rate adjustments may be based on the frequency offset value and/or the current working depth.

A semiconductor circuit may include a first flip-flop configured to output a first input data as a first output signal in response to an inverted input clock signal, a second flip-flop configured to output a second input data as a second output signal in response to an input clock signal, a glitch-free circuit configured to receive the inverted input clock signal, the input clock signal, the first output signal, and the second output signal, and to determine a voltage level of a node on the basis of the inverted input clock signal, the input clock signal, the first output signal, and the second output signal, and an inverter configured to output an output clock signal obtained by inverting the voltage level of the node determined by the glitch-free circuit. The glitch-free circuit does not include a transistor having a gate connected to the node.

Described are apparatus and methods for fractional synchronization using direct digital frequency synthesis (DDFS). A DDFS device includes a memory with N address spaces, a write port circuit configured to sequentially write a digital desired pattern into the N address spaces, a read port circuit configured to readout the digital desired pattern from the N address spaces using continuous sequential automatic addressing from 0 to N−1 at a memory operating frequency clock, where the memory operating frequency clock is based on a sampling frequency clock used for high-speed data processing, and an analog signal processing circuit configured to process a readout digital desired pattern into an analog representation; and output a synthesized frequency clock from the analog representation to a digital core, where the synthesized frequency clock is fractionally synchronized with the sampling frequency clock.

A spike generation circuit includes a first CMOS inverter connected between a first power supply and a second power supply, an output node of the first CMOS inverter being coupled to a first node that is an intermediate node coupled to an input terminal to which an input signal is input, a switch connected in series with the first CMOS inverter, between the first power supply and the second power supply, a first inverting circuit that outputs an inversion signal of a signal of the first node to a control terminal of the switch, and a delay circuit that delays the signal of the first node, outputs a delayed signal to an input node of the first CMOS inverter, and outputs an isolated output spike signal to an output terminal.

A spike generation circuit includes a first CMOS inverter connected between a first power supply and a second power supply, an output node of the first CMOS inverter being coupled to a first node that is an intermediate node coupled to an input terminal to which an input signal is input, a switch connected in series with the first CMOS inverter, between the first power supply and the second power supply, a first inverting circuit that outputs an inversion signal of a signal of the first node to a control terminal of the switch, and a delay circuit that delays the signal of the first node, outputs a delayed signal to an input node of the first CMOS inverter, and outputs an isolated output spike signal to an output terminal.

A clock circuit includes a set of level shifters, a duty cycle adjustment circuit and a calibration circuit. The set of level shifters is configured to output a first set of phase clock signals having a first duty cycle. Each level shifter is configured to output a corresponding phase clock signal of the first set of phase clock signals. The duty cycle adjustment circuit is configured to generate a first clock output signal responsive to at least one of a first or second phase clock signal of the first set of phase clock signals or a set of control signals. The first clock output signal has a second duty cycle. The calibration circuit is configured to perform a duty cycle calibration of the second duty cycle based on an input duty cycle, and generate the set of control signals responsive to the duty cycle calibration of the second duty cycle.

A digital measurement circuit includes a first input flip-flop which receives a first signal through a data input terminal, receives a first clock signal through a clock input terminal, and outputs a second signal; a second input flip-flop which receives the second signal through a data input terminal, receives a second clock signal, which is an inverted signal of the first clock signal, through a clock input terminal, and outputs a third signal; and a delay line which receives the second signal and outputs first through n-th output signals, wherein n is an integer greater than one, and the first through n-th output signals are sampled based on the third signal to output first through n-th sampling signals is provided.

A circuit system is disclosed. In one example, the circuit system includes a clock tree circuit with multiple lanes to which a clock signal is distributed. A duty correction circuit is provided for each of the multiple lanes, and corrects a duty ratio of the clock signal. A clock gating circuit group has a clock gating circuit for each of the multiple lanes and receives, as input, the clock signal from the duty correction circuit. The clock gating circuit group starts output of the clock signal from each of a plurality of the clock gating circuits in a predetermined period. A variable delay circuit is provided in association with each of a plurality of the duty correction circuits and is capable of changing a delay time of a control signal that controls a timing of starting output of the clock signal from the clock gating circuit.

Described is a circuit and architecture that combines phase interpolator (PI) mixer with duty cycle correction (DCC), to prevent cross contention between the tristate inverter pairs of the mixer. The control code for the p-type and n-type networks in the PI mixer are decoupled, and DCC mechanism are blended in the PI mixer code decoding scheme to enable a low latency phase interpolation and duty cycle correction. The circuit comprises a first mixer circuitry controllable by a first code; a second mixer circuitry controllable by a second code; a node coupled to outputs of the first and second mixers; and a keeper circuitry coupled to the node, wherein the first and second mixers are tri-stable mixers.

Systems and methods for adaptively adjusting a slew rate of a dejitter buffer in a remote device in a distributed access architecture. The slew rate may be adjusted based on measurements of a fullness state of a buffer made over time. The measurements may be used to calculate a frequency offset value between the rate at which data leaves the buffer relative to the rate at which data enters the buffer and/or used to calculate a current working depth of the buffer. The adaptive slew rate adjustments may be based on the frequency offset value and/or the current working depth.