Abstract: Clock circuits, components, systems and signal processing methods enabling digital communication are described. A phase locked loop device derives an output signal locked to a first reference clock signal in a feedback loop. A common phase detector is employed to obtain phase differences between a copy of the output signal and a second reference clock signal. The phase differences are employed in an integral phase control loop within the feedback loop to lock the phase locked loop device to the center frequency of the second reference signal. The phase differences are also employed in a proportional phase control loop within the feedback loop to reduce the effect of imperfect component operation. Cascading the integral and proportional phase control within the feedback loop enables an amount of phase error to be filtered out from the output signal.

Abstract: Digital jitter accumulation reduction techniques and circuits are proposed to mitigate jitter accumulation in Voltage Controlled Oscillators (VCOs). In order to reduce jitter accumulation, employing a pair of identical injection locked VCOs is proposed in an interleaved fashion. Further jitter accumulation reductions can be provided by employing a plurality of identical injection locked VCOs selected in a cascading fashion. Yet further jitter accumulation reductions can be provided by resetting the deselected VCO(s).

Abstract: A X-bit Digital-to-Analog Converter (DAC) circuit includes an effective X/2-bit coarse DAC configured to produce a coarse bitstream (CBS) from a digital input DC1 using an nth order Sigma-Delta (??) modulator, and to provide a coarse current source based on the CBS, wherein X is an even integer and n is an integer; an effective X/2-bit fine DAC configured to produce a fine bitstream (FBS) from a digital input DC2 using a 1st order ?? modulator, and to provide a fine current source based on the FBS; and an output configured to form a voltage from the combination of the coarse current source and the fine current source.

Abstract: Techniques and circuits are proposed to increase averaging in the clock recovery band based on an amount of channel overlap in receivers using excess bandwidth for clock recovery, to mitigate the impact of spectral energy leaking into an active channel of interest from an adjacent active channel and to improve the accuracy of the phase estimate of the received transmitted clock.

Abstract: A controlled transconductance circuit (CTC) is disclosed. The CTC includes (i) a transistor comprising a drain terminal, a gate terminal, and a transistor source terminal, (ii) a biasing circuit element connected between the transistor source terminal and a CTC source terminal, and a variable capacitor connected between the transistor source terminal and a constant voltage terminal where the constant voltage terminal is adapted to receive a constant voltage, and (iii) a CTC control terminal adapted to control a transconductance of the CTC by controlling a capacitance of the variable capacitor.

Abstract: Proposed digital on-chip jitter and phase noise measurement techniques and circuits are presented and include the use of a digitally controlled delay locked loop having very fine resolution but limited range to track the phase error between the tested device output clock and its reference clock. Some implementations employ a combination of a high-gain 1-bit phase detector, a digital accumulator and a fine digitally controlled delay element to track the accumulated phase difference between the reference clock and the device under test. Observing the accumulator output is an indication of the jitter and performing a Fast Fourier Transform of the accumulator output provides the phase noise of the device under test.

Abstract: Techniques and circuits are proposed to increase averaging in the clock recovery band based on an amount of channel overlap in receivers using excess bandwidth for clock recovery, to mitigate the impact of spectral energy leaking into an active channel of interest from an adjacent active channel and to improve the accuracy of the phase estimate of the received transmitted clock.

Abstract: Proposed digital on-chip jitter and phase noise measurement techniques and circuits are presented and include the use of a digitally controlled delay locked loop having very fine resolution but limited range to track the phase error between the tested device output clock and its reference clock. Some implementations employ a combination of a high-gain 1-bit phase detector, a digital accumulator and a fine digitally controlled delay element to track the accumulated phase difference between the reference clock and the device under test. Observing the accumulator output is an indication of the jitter and performing a Fast Fourier Transform of the accumulator output provides the phase noise of the device under test.

Abstract: A method for clock recovery that may include obtaining an output signal from a phase locked loop (PLL) device. The method may further include determining, using a digital phase detector, the output signal, and a transmitter clock signal, an amount of phase difference between the output signal and the transmitter clock signal. The method may further include filtering, using a phase rotator and a digital accumulator, a portion of the amount of phase difference from the output signal to generate a filtered signal.

Abstract: A method for clock recovery that may include obtaining an output signal from a phase locked loop (PLL) device. The method may further include determining, using a digital phase detector, the output signal, and a transmitter clock signal, an amount of phase difference between the output signal and the transmitter clock signal. The method may further include filtering, using a phase rotator and a digital accumulator, a portion of the amount of phase difference from the output signal to generate a filtered signal.

Abstract: A controlled transconductance circuit (CTC) is disclosed. The CTC includes (i) a transistor comprising a drain terminal, a gate terminal, and a transistor source terminal, (ii) a biasing circuit element connected between the transistor source terminal and a CTC source terminal, and a variable capacitor connected between the transistor source terminal and a constant voltage terminal where the constant voltage terminal is adapted to receive a constant voltage, and (iii) a CTC control terminal adapted to control a transconductance of the CTC by controlling a capacitance of the variable capacitor.

Abstract: A method for clock recovery that may include obtaining an output signal from a phase locked loop (PLL) device. The method may further include determining, using a digital phase detector, the output signal, and a transmitter clock signal, an amount of phase difference between the output signal and the transmitter clock signal. The method may further include filtering, using a phase rotator and a digital accumulator, a portion of the amount of phase difference from the output signal to generate a filtered signal.

Abstract: A method for filtering noise. The method may include obtaining an output signal from a phase locked loop (PLL) device. The method may include determining, using a digital phase detector and the output signal, an amount of PLL error produced by the PLL device. The method may include filtering, using a delay element and a digital filter, a portion of the amount of PLL error from the output signal to produce a filtered signal in response to determining the amount of PLL error produced by the PLL device.

Abstract: A method for filtering noise. The method may include obtaining an output signal from a phase locked loop (PLL) device. The method may include determining, using a digital phase detector and the output signal, an amount of PLL error produced by the PLL device. The method may include filtering, using a delay element and a digital filter, a portion of the amount of PLL error from the output signal to produce a filtered signal in response to determining the amount of PLL error produced by the PLL device.

Abstract: A method and a circuit are provided for providing phase or frequency synthesis using sigma-delta modulation bit-stream techniques in which data is encoded utilizing sigma-delta modulation and then digital-to-time conversion (DTC) or digital-to-frequency conversion (DFC). In some embodiments this encoded data stream is further subjected to phase or frequency domain filtering, which in some embodiments is carried out by a higher-order phase-locked loop (PLL).

Abstract: The present invention relates to a method and system for providing an analog Gaussian noise signal having the predetermined probability distribution function, bandwidth and center frequency. A band-limited digital noise signal indicative of a Gaussian noise signal having a predetermined Gaussian probability distribution function is ?? modulated generating a pulse-density modulated 1-bit sequence representing a Gaussian noise signal having a predetermined probability distribution function, bandwidth and center frequency. Using an analog low-pass filter the pulse-density modulated 1-bit sequence is then converted into a respective analog Gaussian noise signal having the predetermined probability distribution function, bandwidth and center frequency. The method and system are successfully employed in numerous applications such as in histogram testing and probabilistic digitization.

Abstract: A method and a circuit are provided for providing phase or frequency synthesis using sigma-delta modulation bit-stream techniques in which data is encoded utilizing sigma-delta modulation and then digital-to-time conversion (DTC) or digital-to-frequency conversion (DFC). In some embodiments this encoded data stream is further subjected to phase or frequency domain filtering, which in some embodiments is carried out by a higher-order phase-locked loop (PLL).

Abstract: The present invention relates to a method and system for providing an analog Gaussian noise signal having the predetermined probability distribution function, bandwidth and center frequency. A band-limited digital noise signal indicative of a Gaussian noise signal having a predetermined Gaussian probability distribution function is ?? modulated generating a pulse-density modulated 1-bit sequence representing a Gaussian noise signal having a predetermined probability distribution function, bandwidth and center frequency. Using an analog low-pass filter the pulse-density modulated 1-bit sequence is then converted into a respective analog Gaussian noise signal having the predetermined probability distribution function, bandwidth and center frequency. The method and system are successfully employed in numerous applications such as in histogram testing and probabilistic digitization.