Abstract: A timing device includes an oven having a chamber, a crystal oscillator disposed in the chamber that generates a clock signal, and one or more sensors to generate operational characteristic signals indicative of respective operational characteristics of the crystal oscillator or the oven. The timing device includes a plurality of I/O connections and an IC device. The IC device includes processing logic to generate information that indicates how the generated clock signal is to be modified and a modulator coupled to the processing logic and the crystal oscillator. The modulator modulates the generated clock signal in relation to the information to generate a modulated clock signal indicative of the one or more operational characteristics of the crystal oscillator or the oven. The modulator outputs the modulated clock signal over a single one of the plurality of I/O connections.

Abstract: A timing device includes an oven having a chamber, a crystal oscillator disposed in the chamber that generates a clock signal, and one or more sensors to generate operational characteristic signals indicative of respective operational characteristics of the crystal oscillator or the oven. The timing device includes a plurality of I/O connections and an IC device. The IC device includes processing logic to generate information that indicates how the generated clock signal is to be modified and a modulator coupled to the processing logic and the crystal oscillator. The modulator modulates the generated clock signal in relation to the information to generate a modulated clock signal indicative of the one or more operational characteristics of the crystal oscillator or the oven. The modulator outputs the modulated clock signal over a single one of the plurality of I/O connections.

Abstract: A circuit for generating temperature-stable clocks including first and second crystal oscillators, an input for a reference clock source, a clock output, a first phase acquisition circuit coupled to the first and second crystal oscillators, a second phase acquisition circuit coupled to the input for the reference clock source and to the second crystal oscillator, a first DPLL coupled to the first phase acquisition circuit, a crystal oscillator variation estimator coupled to the first DPLL, a second DPLL coupled to the second phase acquisition circuit and including a phase-frequency detector having a input coupled to the second phase acquisition circuit, a loop filter, a frequency subtractor having an input coupled to the loop filter and an input coupled to the crystal oscillator variation estimator, and a DCO coupled to the frequency subtractor and driving an input of the phase-frequency detector.

Abstract: A method for transferring first and second encoded client clock signals over a carrier clock domain between integrated circuits, including in a first integrated circuit encoding a phase change of the first client clock signal from a last recorded phase onto the carrier clock signal in first bit positions, encoding a phase change of the second client clock signal from a last recorded phase onto the carrier clock signal in second bit positions different from the first bit positions, and transmitting the carrier clock signal with the encoded phases of the first client clock signal and the second client clock signal over a single wire from the first integrated circuit to a second integrated circuit.

Abstract: A clock recovery device recovers a master clock over a packet network from incoming synchronization packets. A frequency locked loop generates a control input to a controlled oscillator, which generates an output clock. The frequency locked loop is responsive to pure offset information obtained from the incoming synchronization packets. A transient phase adjuster extracts information from the incoming synchronization packets taking into account transit delays to effect fast frequency adjustment of the control input and to provide a phase adjustment input to the frequency locked loop. A secondary phase path is selectable in response to de-activation of the transient phase adjuster to provide a phase correction to the control input derived from said pure offset information when the transient phase adjuster is inactive.

Abstract: A method of compensating for integral nonlinear interpolation (INL) distortion in a clock synthesizer driven by a system clock running at a frequency fsys, involves introducing a selected nominal analog delay I*dt with an actual delay of I*dt+? at the output of the a first path with a digital controlled oscillator (DCO) and a digital-to-time converter (DTC) and a nominal digital delay I*D with an actual delay of I*D+? at the input of a second path with a DCO and a DTC that offsets the actual analog delay in the first path, adjusting the contents x(k) of a compensation module in the second path to align the output pulses of the first and second paths for different values of k, where k represents an interpolation point, iteratively repeating the two preceding steps for all N values of I, and averaging the contents x(k) of the compensation module to derive the compensation values to be applied to a one of the DTCs to correct for INL distortion.

Abstract: To speed up output clock alignment in a digital phase locked loop wherein a controlled oscillator generates synthesizer pulses that are divided to produce output pulses at a predetermined normal spacing and time location, and wherein during an alignment procedure the output pulses are moved in time in response to a delay value obtained by comparing a phase of the output pulses with a phase applied to the controlled oscillator averaged over a number of synthesizer pulses in a feedback circuit to align said output pulses with a reference clock taking into account hardware delay, a group of the output pulses is advanced during the alignment procedure to reduce the spacing between them. After determining the delay value averaged over the group of output pulses subsequent output pulses are restored to their normal spacing and time locations.

Abstract: A method of compensating for integral nonlinear interpolation (INL) distortion in a clock synthesizer driven by a system clock running at a frequency fsys, involves introducing a selected nominal analog delay I*dt with an actual delay of I*dt+? at the output of the a first path with a digital controlled oscillator (DCO) and a digital-to-time converter (DTC) and a nominal digital delay I*D with an actual delay of I*D+? at the input of a second path with a DCO and a DTC that offsets the actual analog delay in the first path, adjusting the contents x(k) of a compensation module in the second path to align the output pulses of the first and second paths for different values of k, where k represents an interpolation point, iteratively repeating the two preceding steps for all N values of I, and averaging the contents x(k) of the compensation module to derive the compensation values to be applied to a one of the DTCs to correct for INL distortion.

Abstract: A clock recovery device recovers a master clock over a packet network from incoming synchronization packets. A frequency locked loop generates a control input to a controlled oscillator, which generates an output clock. The frequency locked loop is responsive to pure offset information obtained from the incoming synchronization packets. A transient phase adjuster extracts information from the incoming synchronization packets taking into account transit delays to effect fast frequency adjustment of the control input and to provide a phase adjustment input to the frequency locked loop. A secondary phase path is selectable in response to de-activation of the transient phase adjuster to provide a phase correction to the control input derived from said pure offset information when the transient phase adjuster is inactive.

Abstract: To speed up output clock alignment in a digital phase locked loop wherein a controlled oscillator generates synthesizer pulses that are divided to produce output pulses at a predetermined normal spacing and time location, and wherein during an alignment procedure the output pulses are moved in time in response to a delay value obtained by comparing a phase of the output pulses with a phase applied to the controlled oscillator averaged over a number of synthesizer pulses in a feedback circuit to align said output pulses with a reference clock taking into account hardware delay, a group of the output pulses is advanced during the alignment procedure to reduce the spacing between them. After determining the delay value averaged over the group of output pulses subsequent output pulses are restored to their normal spacing and time locations.

Abstract: A loop filter in a modified phase locked loop has a proportional path generating first output signal that is proportional to an input signal and an integral path for generating a second output signal that is an integral of the input signal. An additional functional path generates a third output signal that is a predetermined function of the input signal. The predetermined function is of the form f(s)/g(s), where f and g are polynomial functions. An adder combines the first, second, and third output signals into a common output signal.

Abstract: A multi-loop phase locked loop (PLL) system with noise attenuation has a first PLL including a local oscillator, a second PLL coupled to an output of the first PLL, and a third PLL in a feedback path between the second PLL and first PLL. A first phase comparator compares an input signal with the first feedback signal to generate a first phase error signal for the first PLL. The first phase error signal is multiplied by a scaling factor k determining the amount of noise attenuation. The third PLL has a bandwidth preferably at least ten times higher than the second PLL so that the overall transfer function of the second and third PLLs is approximately the transfer function of the second PLL. The transfer function of the third PLL is multiplied by a scaling factor 1/k. This arrangement allows the use of an uncompensated local oscillator in the first PLL. The noise generated in the uncompensated local oscillator is reduced by the attenuation factor k.

Abstract: A loop filter in a modified phase locked loop has a proportional path generating first output signal that is proportional to an input signal and an integral path for generating a second output signal that is an integral of the input signal. An additional functional path generates a third output signal that is a predetermined function of the input signal. The predetermined function is of the form f(s)/g(s), where f and g are polynomial functions. An adder combines the first, second, and third output signals into a common output signal.

Abstract: A network interface for recovering timing information over packet networks has line card at the edge of a local network and a timing card separate from the line card. A physical interface time-stamps incoming timing packets based on smoothed recovered clock signals. A clock recovery module on the line card generates timing signals from the time-stamped incoming timing packets. A first phase locked generates raw clock signals from the timing signals. A second phase locked loop on the timing card generates the smoothed clock signals from said raw clock signals and applies them to the clock recovery module on the line card.

Abstract: A multi-loop phase locked loop (PLL) system with noise attenuation has a first PLL including a local oscillator, a second PLL coupled to an output of the first PLL, and a third PLL in a feedback path between the second PLL and first PLL. A first phase comparator compares an input signal with the first feedback signal to generate a first phase error signal for the first PLL. The first phase error signal is multiplied by a scaling factor k determining the amount of noise attenuation. The third PLL has a bandwidth preferably at least ten times higher than the second PLL so that the overall transfer function of the second and third PLLs is approximately the transfer function of the second PLL. The transfer function of the third PLL is multiplied by a scaling factor 1/k. This arrangement allows the use of an uncompensated local oscillator in the first PLL. The noise generated in the uncompensated local oscillator is reduced by the attenuation factor k.

Abstract: A network interface for recovering timing information over packet networks has line card at the edge of a local network and a timing card separate from the line card. A physical interface time-stamps incoming timing packets based on smoothed recovered clock signals. A clock recovery module on the line card generates timing signals from the time-stamped incoming timing packets. A first phase locked generates raw clock signals from the timing signals. A second phase locked loop on the timing card generates the smoothed clock signals from said raw clock signals and applies them to the clock recovery module on the line card.

Abstract: A method of reducing noise in an environment where the noise source is in a fixed location relative to a pair of microphones, such as in a camera with a zoom motor, involves receiving signals x1(t), x2(t) from the respective microphones, and filtering each of the signals x1(t), x2(t) with respective first and second linear filters having filter coefficients obtained by computing eigenfilters corresponding to data samples from the respective microphones for noise only and signal only conditions.

Abstract: Phase slope is controlled in a phase locked loop wherein a phase error signal controlling a controlled oscillator has a proportional component and an integral component, by determining whether the proportional component falls within a range bounded by upper and lower limit values. The proportional component is combined with the integral component if the proportional component falls within the range to provide the phase error signal. Otherwise, the proportional component is modified to meet a phase slope requirement while leaving the integral component unmodified. The modified proportional component is combined with the unmodified integral component to provide the phase error signal.

Abstract: Phase slope is controlled in a phase locked loop wherein a phase error signal controlling a controlled oscillator has a proportional component and an integral component, by determining whether the proportional component falls within a range bounded by upper and lower limit values. The proportional component is combined with the integral component if the proportional component falls within the range to provide the phase error signal. Otherwise, the proportional component is modified to meet a phase slope requirement while leaving the integral component unmodified. The modified proportional component is combined with the unmodified integral component to provide the phase error signal.

Abstract: In a method of recovering timing information over packet networks, a receiver receives a plurality of packet streams over different paths from the same source. The raw delays experienced by the timing packets for each stream are filtered to provide a filtered delay for each stream. The filtered delays are weighted based on the quality of each stream, and the weighted filtered delays are then combined to form an aggregate delay estimate. Frequency adjustments for a local clock at the receiver are derived from the aggregate delay estimate.