A delay line includes a first delay cell and a second delay cell. The first delay cell inverts an input signal to generate a first output signal. The second delay cell inverts the first output signal to generate a second output signal. The driving forces of the first delay cell is adjusted on the basis of a delay control voltage and the second output signal.

The present invention is directed to electrical circuits. According to an embodiment, the present invention provides a charge pump circuit with a bias section and a switch section. The switch section includes a first switch coupled to an early signal and a second switch coupled to a late signal. The charge pump additionally includes a low-pass filter. The switch section includes a first resistor and a second resistor. The first resistor is directly coupled to the first switch and the low-pass filter. The second resistor is directly coupled to the second switch and the first resistor. There are other embodiments as well.

Various embodiments relate to a PLL based FSK demodulator, the FSK demodulator comprising a PFD configured to receive an input signal, a fully differential auxiliary charge pump configured to receive and amplify the input signal from the PFD, a capacitor configured to filter the input signal from the auxiliary charge pump and a fully differential slicer configured to demodulate the input signal and output recovered data.

A sine to square wave converter circuit receives a sine wave signal and supplies a first square wave signal having a first frequency. A 2 clock multiplier circuit multiplies the first square wave signal and supplies a second square wave signal with a second frequency that is twice the first frequency. A first storage element that is clocked by the second square wave signal stores a delayed version of the first square wave signal and supplies an even-odd signal. A second storage element that is clocked by the second square wave signal receives the even-odd signal and supplies an odd-even signal. A duty cycle correction circuit adjusts the threshold of the sine to square wave converter based on a difference in duty pulse widths between the even-odd signal and the odd-even signal.

A phase-locked loop circuit includes a delay phase-locked loop and a sub-sampling phase-locked loop. The delay phase-locked loop phase locks a first reference clock and a second reference clock to an input clock, and includes a phase correction circuit, an integrator, a first sub-sampling phase detector, and a first charge pump. The sub-sampling phase-locked loop is configured to generate an output clock with a predetermined phase-locked loop frequency, and the output clock is phase-locked to the first reference clock, the sub-sampling phase-locked loop includes a second sub-sampling phase detector, a second charge pump, a phase frequency detecting circuit, a voltage controlled oscillator and a first frequency divider. The first sub-sampling phase detector and the second sub-sampling phase detector have a symmetric circuit structure, and a first charge pump circuit and a second charge pump circuit have a symmetric circuit structure.

Embodiments of a method for operating a charge pump and a charge pump are disclosed. In an embodiment, a method for operating a charge pump involves during a first operating phase of the charge pump, setting a first current source of the charge pump according to a second current source of the charge pump, and, during a second operating phase of the charge pump that is subsequent to the first operating phase, providing current from the first current source to a load of the charge pump.

The present invention is directed to electrical circuits. According to an embodiment, the present invention provides a charge pump circuit with a bias section and a switch section. The switch section includes a first switch coupled to an early signal and a second switch coupled to a late signal. The charge pump additionally includes a low-pass filter. The switch section includes a first resistor and a second resistor. The first resistor is directly coupled to the first switch and the low-pass filter. The second resistor is directly coupled to the second switch and the first resistor. There are other embodiments as well.

Multi-mode non-return-to-zero (NRZ) and orthogonal differential vector signaling (ODVS) clock and data recovery circuits having configurable sub-channel multi-input comparator (MIC) circuits for forming a composite phase-error signal from a plurality of data-driven phase-error signals generated using phase detectors in a plurality of receivers configured as ODVS sub-channel MICs generating orthogonal sub-channel outputs in a first mode and a separate first and second data driven phase-error signal from two receivers of a plurality of receivers configured as NRZ receivers in a second mode.

In one embodiment, a filter circuit is formed to include a transconductance amplifier. The filter circuit has one pair of capacitors connected between at least one input of the amplifier and an input signal that is to be filtered.

A unity gain buffer is shared by a charge pump and an active loop filter in a phase-locked loop. The charge pump uses the unity gain buffer to reduce current mismatch in the charge pump and the active loop filter uses the unity gain buffer in a circuit that increases the effective capacitance of the active loop filter.