Aspects of the disclosure provide a receiver for receiving data over a wired communication channel. The receiver includes an analog front end circuit, a pulse generation circuit and a voltage-controlled oscillator (VCO). The analog front end circuit receives an analog signal carrying data over the wired communication channel, and outputs a data signal with data bit transitions between voltage levels. The pulse generation circuit generates a pulse signal in response to the data bit transitions in the data signal. The voltage-controlled oscillator (VCO) generates an oscillation signal for providing sampling clocks for the data signal. The voltage-controlled oscillator aligns transitions in the oscillation signal to the pulse signal by forcing the oscillation signal to transit voltage levels in response to a pulse in the pulse signal.

A system for generating an RFPWM signal comprises a delta sigma modulator having a plurality of outputs, a phase-locked loop comprising a plurality of phase quantization outputs, at least one multiplexer having a plurality of signal inputs, a plurality of selector inputs, and at least one output, the signal inputs communicatively connected to the phase quantization outputs of the phase-locked loop and the selector inputs electrically connected to the outputs of the delta sigma modulator, and a driver having an input communicatively connected to the output of the multiplexer and an output generating an RFPWM signal. A method of generating an RFPWM signal is also described.

A variable delay circuit includes first pull-up and first pull-down current paths and second pull-up and second pull-down current paths. The variable delay circuit generates first delays in an output signal relative to an input signal in response to the first pull-up and first pull-down current paths being enabled by a first control signal. The variable delay circuit generates second delays in the output signal relative to the input signal that are different than the first delays in response to the second pull-up and second pull-down current paths being enabled by a second control signal.

Methods and systems are described for generating multiple phases of a local clock at a controllable variable frequency, using loop-connected strings of active circuit elements. A specific embodiment incorporates a loop of four active circuit elements, each element providing true and complement outputs that are cross-coupled to maintain a fixed phase relationship, and feed-forward connections at each loop node to facilitate high frequency operation. A particular physical layout is described that maximizes operating frequency and minimizes clock pertubations caused by unbalanced or asymmetric signal paths and parasitic node capacitances.

A method of generating precise and PVT-stable time delay or frequency using CMOS circuits is disclosed. In some implementations, the method includes providing a reference voltage using a resistive module at a positive input terminal of an operational amplifier, coupling gates of a pair of p-type metal oxide semiconductor (pMOS) transistors and a compensation capacitor to an output terminal of the operational amplifier to generate a first bias signal, and coupling a pair of n-type metal oxide semiconductor (nMOS) transistors to a negative terminal of the operational amplifier to generate a second bias signal at the negative terminal, wherein the pair of nMOS transistors is substantially the same as a pair of nMOS transistors in the CMOS delay circuit.

An oscillator circuit comprises differential amplifiers connected in series and an auxiliary start circuit. A first output terminal and a second output terminal of each differential amplifier are respectively coupled to a first input terminal and a second input terminal of the next differential amplifier. Said first output terminal of the last differential amplifier is coupled to said second input terminal of the first differential amplifier. Said second output terminal of said last differential amplifier is coupled to said first input terminal of said first differential amplifiers. Said auxiliary start circuit generates a first disturbance signal and a second disturbance signal to said first input terminal and said second input terminal of a second differential amplifier according to said signal state of said first input terminal of a first differential amplifier. Said first different amplifier is one of said differential amplifiers. Said second differential amplifier is another differential amplifier.

A ring voltage controlled oscillator (VCO) circuit is herein provided. According to one embodiment, a ring VCO circuit includes a plurality of stages connected in series, wherein each stage includes a first inverter, a second inverter, a third inverter and a fourth inverter, the first inverter connected in parallel with the third and fourth inverters and the second inverter connected in parallel with the third and fourth inverters, and a first biasing resistor connected to a first node and coupled to an input of the first inverter. The first biasing resistor includes a first switch configured to set the first biasing resistor to about zero voltage.

An electronic device comprises a regulator, and an oscillator and a resistor coupled to the regulator. The electronic device further comprises a feedback controller that includes a differential amplifier coupled between the oscillator, the resistor, and the regulator. The feedback controller is configured to apply a control voltage to the regulator in response to a resistor voltage upon the resistor and an oscillator voltage upon the oscillator. The feedback controller can be coupled to control a substantially equal voltage upon the resistor and the oscillator.

Methods and systems for regulating supply voltage is described. In an example, a device can receive unregulated supply. The device can be connected to a ring oscillator and an integrated circuit. The device can be configured to regulate the unregulated supply to a first voltage. The device can be further configured to provide the regulated supply to the ring oscillator, where the ring oscillator operates with the regulated supply. The device can be further configured to, in response to a change in the regulated supply from the first voltage to a second voltage, adjust the changed regulated supply to return to the first voltage to cause the ring oscillator to operate with a constant regulated supply having the first voltage.

A phase-locked loop circuitry (200) having low variation transconductance design comprises a voltage controlled oscillator structure (308) to provide an output signal (Fosc) having an oscillation frequency. The voltage controlled oscillator structure (308) comprises a voltage-to-current converter circuit (312) and a current controlled oscillator circuit (314). The voltage-to-current converter circuit is designed with a low variation transconductance. The voltage-controlled oscillator circuit (200) has a characteristic curve being independent of different PVT (processes, supply voltages and temperature) conditions to ensure that the phase-locked loop circuitry (200) is stable under different PVT condition.