Abstract: Optical switches and methods of switching include a first hybrid coupler configured to accept an input and to provide two branches. A phase tuner on a first branch includes a Mach-Zehnder phase shifter configured to shift a signal on the first branch by a selected phase. A loss compensator on a second branch is configured to match a loss incurred on the first branch. A second hybrid coupler is configured to recombine the two branches such that the phase shift generated by the phase tuner determines which output of the second hybrid coupler is used.

Abstract: An apparatus comprises a digitally controlled circuit having a variable capacitance and a controller configured to adjust a magnitude of the variable capacitance of the digitally controlled circuit. The digitally controlled circuit comprises a plurality of gain elements, the plurality of gain elements comprising one or more positive voltage-to-frequency gain elements and one or more negative voltage-to-frequency gain elements. The controller is configured to adjust the magnitude of the capacitance by adjusting the gain provided by respective ones of the gain elements in an alternating sequence of the positive voltage-to-frequency gain elements and the negative voltage-to-frequency gain elements.

Abstract: Methods and devices for phase adjustment include a phase detector that is configured to compare a reference clock and a feedback clock and to generate two output signals. A difference in time between pulse widths of the two output signals corresponds to a phase difference between the reference clock and the feedback clock. A programmable delay line is configured to delay an earlier output signal in accordance with a predicted deterministic phase error. An oscillator is configured to generate a feedback signal in accordance with the delayed output signal. A divider is configured to divide a frequency of the oscillator output by an integer N. The integer N is varied to achieve an average fractional divide ratio and the predicted deterministic phase error is based on the average divide ratio and an instantaneous divide ratio.

Abstract: An apparatus comprises a digitally controlled circuit having a variable capacitance and a controller configured to adjust a magnitude of the variable capacitance of the digitally controlled circuit. The digitally controlled circuit comprises a plurality of gain elements, the plurality of gain elements comprising one or more positive voltage-to-frequency gain elements and one or more negative voltage-to-frequency gain elements. The controller is configured to adjust the magnitude of the capacitance by adjusting the gain provided by respective ones of the gain elements in an alternating sequence of the positive voltage-to-frequency gain elements and the negative voltage-to-frequency gain elements.

Abstract: Methods and systems for phase correction include determining a phase error direction and generating a prediction for the phase error based on a sigma-delta error. It is determined whether the prediction agrees with the determined phase error direction. If the prediction does not agree, a phase correction is adjusted in accordance with the predicted phase error.

Abstract: Methods and devices for phase adjustment include a phase detector that is configured to compare a reference clock and a feedback clock and to generate two output signals. A difference in time between pulse widths of the two output signals corresponds to a phase difference between the reference clock and the feedback clock. A programmable delay line is configured to delay an earlier output signal in accordance with a predicted deterministic phase error. An oscillator is configured to generate a feedback signal in accordance with the delayed output signal. A divider is configured to divide a frequency of the oscillator output by an integer N. The integer N is varied to achieve an average fractional divide ratio and the predicted deterministic phase error is based on the average divide ratio and an instantaneous divide ratio.

Abstract: Methods an systems for low-power transmission include biasing an emitter in a non-linear operating range of the emitter near a threshold current of the emitter. A data signal is distorted to add a precursor pulse to a rising edge of a data waveform to quickly bring the emitter into a linear operating range. The distorted data signal is transmitted at the emitter.

Abstract: An apparatus comprises a resonator including a plurality of switched impedances spatially distributed within the resonator and a corresponding plurality of transconductance elements distributed within respective distances among the switched impedances. The resonator has a given desired resonant frequency and a given amplitude of response. Combined pairs of the switched impedances and transconductance elements have respective parasitic resonant frequencies which are higher than the given desired resonant frequency and have respective amplitudes of response which are lower than the given amplitude of response. The apparatus may be a voltage controlled oscillator or an active filter.

Abstract: Methods and systems for phase correction include determining a phase error direction and generating a prediction for the phase error based on a sigma-delta error. It is determined whether the prediction agrees with the determined phase error direction. If the prediction does not agree, a phase correction is adjusted in accordance with the predicted phase error.

Abstract: An apparatus comprises a digitally controlled circuit having a variable capacitance and a controller configured to adjust a magnitude of the variable capacitance of the digitally controlled circuit. The digitally controlled circuit comprises a plurality of gain elements, the plurality of gain elements comprising one or more positive voltage-to-frequency gain elements and one or more negative voltage-to-frequency gain elements. The controller is configured to adjust the magnitude of the capacitance by adjusting the gain provided by respective ones of the gain elements in an alternating sequence of the positive voltage-to-frequency gain elements and the negative voltage-to-frequency gain elements.

Abstract: An apparatus comprises a digitally controlled circuit having a variable capacitance and a controller configured to adjust a magnitude of the variable capacitance of the digitally controlled circuit. The digitally controlled circuit comprises a plurality of gain elements, the plurality of gain elements comprising one or more positive voltage-to-frequency gain elements and one or more negative voltage-to-frequency gain elements. The controller is configured to adjust the magnitude of the capacitance by adjusting the gain provided by respective ones of the gain elements in an alternating sequence of the positive voltage-to-frequency gain elements and the negative voltage-to-frequency gain elements.

Abstract: Designing a photonics switching system is provided. A photonic switch diode is designed to attain each performance metric in a plurality of performance metrics associated with a photonic switching system based on a weighted value corresponding to each of the plurality of performance metrics. A switch driver circuit is selected from a plurality of switch driver circuits for the photonic switching system. It is determined whether each performance metric associated with the photonic switching system meets or exceeds a threshold value corresponding to each of the plurality of performance metrics based on the designed photonic switch diode and the selected switch driver circuit. In response to determining that each performance metric associated with the photonic switching system meets or exceeds the threshold value corresponding to each of the performance metrics, the photonic switching system is designed using the designed photonic switch diode and the selected switch driver circuit.

Abstract: A method includes forming a resonator comprising a plurality of switched impedances spatially distributed within the resonator, selecting a resonant frequency for the resonator, and distributing two or more transconductance elements within the resonator based on the selected resonant frequency. Distributing the two or more transconductance elements may include non-uniformly distributing the two or more transconductance elements within the resonator.

Abstract: A method and system are disclosed for measuring a specified parameter in a phase-locked loop frequency synthesizer (PLL). In one embodiment, the method comprises introducing multiple phase errors in the PLL, measuring a specified aspect of the introduced phase errors, and determining a value for the specified parameter using the measured aspects of the introduced phase errors. In one embodiment, the phase errors are introduced repetitively in the PLL, and these phase errors produce a modified phase difference between the reference signal and the feedback signal in the PPL. In one embodiment, crossover times, when this modified phase difference crosses over a preset value, are determined, and these crossover times are used to determine the value for the specified parameter. In an embodiment, the parameter is calculated as a mathematical function of the crossover times. The parameter may be, for example, the bandwidth of the PLL.

Abstract: Methods and devices for phase adjustment include a phase detector that is configured to compare a reference clock and a feedback clock and to generate two output signals. A difference in time between pulse widths of the two output signals corresponds to a phase difference between the reference clock and the feedback clock. A programmable delay line is configured to delay an earlier output signal in accordance with a predicted deterministic phase error. An oscillator is configured to generate a feedback signal in accordance with the delayed output signal. A divider is configured to divide a frequency of the oscillator output by an integer N. The integer N is varied to achieve an average fractional divide ratio and the predicted deterministic phase error is based on the average divide ratio and an instantaneous divide ratio.

Abstract: Methods and systems for phase correction include determining a phase error direction and generating a prediction for the phase error based on a sigma-delta error. It is determined whether the prediction agrees with the determined phase error direction. If the prediction does not agree, a phase correction is adjusted in accordance with the predicted phase error.

Abstract: Designing a photonics switching system is provided. A photonic switch diode is designed to attain each performance metric in a plurality of performance metrics associated with a photonic switching system based on a weighted value corresponding to each of the plurality of performance metrics. A switch driver circuit is selected from a plurality of switch driver circuits for the photonic switching system. It is determined whether each performance metric associated with the photonic switching system meets or exceeds a threshold value corresponding to each of the plurality of performance metrics based on the designed photonic switch diode and the selected switch driver circuit. In response to determining that each performance metric associated with the photonic switching system meets or exceeds the threshold value corresponding to each of the performance metrics, the photonic switching system is designed using the designed photonic switch diode and the selected switch driver circuit.

Abstract: A method and system are disclosed for measuring a specified parameter in a phase-locked loop frequency synthesizer (PLL). In one embodiment, the method comprises introducing multiple phase errors in the PLL, measuring a specified aspect of the introduced phase errors, and determining a value for the specified parameter using the measured aspects of the introduced phase errors. In one embodiment, the phase errors are introduced repetitively in the PLL, and these phase errors produce a modified phase difference between the reference signal and the feedback signal in the PPL. In one embodiment, crossover times, when this modified phase difference crosses over a preset value, are determined, and these crossover times are used to determine the value for the specified parameter. In an embodiment, the parameter is calculated as a mathematical function of the crossover times. The parameter may be, for example, the bandwidth of the PLL.

Abstract: An apparatus comprises a resonator including a plurality of switched impedances spatially distributed within the resonator and a corresponding plurality of transconductance elements distributed within respective distances among the switched impedances. The resonator has a given desired resonant frequency and a given amplitude of response. Combined pairs of the switched impedances and transconductance elements have respective parasitic resonant frequencies which are higher than the given desired resonant frequency and have respective amplitudes of response which are lower than the given amplitude of response. The apparatus may be a voltage controlled oscillator or an active filter.

Abstract: Methods and systems for phase correction include determining a phase error direction and generating a prediction for the phase error based on a sigma-delta error. It is determined whether the prediction agrees with the determined phase error direction. If the prediction does not agree, a phase correction is adjusted in accordance with the predicted phase error.