A frequency synthesizer employs a combination of a low divide ratio divider phase-locked loop (PLL) and a wide band, on-chip voltage-controlled oscillator (VCO). To reduce phase noise, low divide ratio phase detection is employed. By using the off-chip PLL with a bank of on-chip VCOs, the frequency synthesizer may have enhanced frequency stability and avoid having to include an acquisition circuit. A separation between the PLL and VCO may reduce integer boundary spurs (IBS) eliminating or reducing a need for a filter bank and switches reducing a complexity of the frequency synthesizer.

The present invention is directed to electrical circuits. More specifically, embodiments of the present invention provide a charge pump, which can be utilized as a part of a clock data recovery device. Early and late signals are used as differential switching voltage signals in the charge pump. The first switch and a second switch are used for controlling the direction of the current flowing into the loop filter. Input differential voltages to the switches are being generated with an opamp negative feedback loop. The output voltage of the first switch and the second switch is used in conjunction with a resistor to generate a charge pump current. There are other embodiments as well.

The present invention is directed to electrical circuits. More specifically, embodiments of the present invention provide a charge pump, which can be utilized as a part of a clock data recovery device. Early and late signals are used as differential switching voltage signals in the charge pump. The first switch and a second switch are used for controlling the direction of the current flowing into the loop filter. Input differential voltages to the switches are being generated with an opamp negative feedback loop. The output voltage of the first switch and the second switch is used in conjunction with a resistor to generate a charge pump current. There are other embodiments as well.

Embodiments are directed to apparatuses and methods involving a phase-error tracking circuit. An example apparatus includes a divide-by phase locked loop (PLL) circuit to generate a continuous wave signal that sweeps over a frequency range in response to a divider feedback signal and to a reference signal. The apparatus further includes the phase-error tracking circuit defining a phase-error window in which the divide-by PLL circuit is to lock based on a slope associated with a rate of change of the frequency range, and indicating whether a phase error between the divider feedback signal and the reference signal coincides with the phase-error window.

Embodiments are directed to apparatuses and methods involving a phase-error tracking circuit. An example apparatus includes a divide-by phase locked loop (PLL) circuit to generate a continuous wave signal that sweeps over a frequency range in response to a divider feedback signal and to a reference signal. The apparatus further includes the phase-error tracking circuit defining a phase-error window in which the divide-by PLL circuit is to lock based on a slope associated with a rate of change of the frequency range, and indicating whether a phase error between the divider feedback signal and the reference signal coincides with the phase-error window.

A phase-locked loop (PLL) for generating a VCO output signal at a target frequency has been disclosed. The PLL includes at least first and second VCOs, first and second multiplexers, and a frequency divider. The first and second VCOs generate first and second output signals over first and second frequency ranges, respectively. The first multiplexer receives the first and second output signals from the first and second VCOs, respectively, and outputs the first output signal when the target frequency is in the first frequency range and the second output signal when the target frequency is in the second frequency range or less than the first frequency range. The frequency divider divides a frequency of the second output signal by a division factor to generate a third output signal. The second multiplexer outputs one of the first, second, and third output signals as the VCO output signal.

A phase-locked loop (PLL) for generating a VCO output signal at a target frequency has been disclosed. The PLL includes at least first and second VCOs, first and second multiplexers, and a frequency divider. The first and second VCOs generate first and second output signals over first and second frequency ranges, respectively. The first multiplexer receives the first and second output signals from the first and second VCOs, respectively, and outputs the first output signal when the target frequency is in the first frequency range and the second output signal when the target frequency is in the second frequency range or less than the first frequency range. The frequency divider divides a frequency of the second output signal by a division factor to generate a third output signal. The second multiplexer outputs one of the first, second, and third output signals as the VCO output signal.

A controller for use in a power converter including a jitter generator circuit coupled to receive a drive signal from a switch controller and generate a jitter signal. The jitter signal is a modulated jitter signal when the drive signal is below a first threshold frequency. The switch controller is coupled to a power switch coupled to an energy transfer element. The switch controller is coupled to receive a current sense signal representative of a current through the power switch. The switch controller is coupled to generate the drive signal to control switching of the power switch in response to the current sense signal and the jitter signal to control a transfer of energy from an input of the power converter to an output of the power converter.

A controller for use in a power converter including a jitter generator circuit coupled to receive a drive signal from a switch controller and generate a jitter signal. The jitter signal is a modulated jitter signal when the drive signal is below a first threshold frequency. The switch controller is coupled to a power switch coupled to an energy transfer element. The switch controller is coupled to receive a current sense signal representative of a current through the power switch. The switch controller is coupled to generate the drive signal to control switching of the power switch in response to the current sense signal and the jitter signal to control a transfer of energy from an input of the power converter to an output of the power converter.

A sub-ranging time-to-digital converter (TDC) is disclosed that includes two ring oscillators for determining a time difference between two clock edges.