Abstract: A voltage or current regulator has a power DAC and ADC in a negative feedback loop, locked to a reference voltage or current. The ADC may have one or more parallel comparators followed by one or more parallel filters. The regulator may include a multiplexer to select between filter output signals and to forward the selected signal to the power DAC. The regulator may receive power management mode control codes to modify filter behavior and/or to select between multiple parallel filters. By modifying the loop behavior, the regulator is able to swiftly change between power management modes supporting different power level and noise profiles. Regulators with a single comparator can lock the output to a single reference voltage or current. Regulators with two comparators can regulate the output to vary within a range limited by an upper and a lower reference voltage or current.

Abstract: A comparator circuit has a sense amplifier with a differential pair, a voltage excursion limiter, and a switch. The differential pair receives two analog input signals. Its differential outputs operate at a common mode voltage approximately half the supply voltage. The voltage limiter is coupled with one of the differential pair outputs. A capacitor may store comparison results. The switch energizes the differential pair and the voltage excursion limiter during a first phase of a clock, and de-energizes them during a second phase of the clock. During this phase, the comparator may provide the stored comparison result to an amplifier with positive feedback.

Abstract: A PLL includes an oscillator, multiple time-to-digital converters (TDCs) and a system for the remaining functionality. The TDCs measure the oscillator's phase against respective multiple reference clocks. The system compares the respective measured phases with respective desired phases to obtain phase error signals. One is selected to close the loop. The others are monitored and adjusted when not equal to zero. When a new reference clock must be used, the loop is changed from including the old phase error signal to the new. The old phase error was zero because the loop was in lock, the new phase error is zero because it was monitored and adjusted. Therefore, upon switching the loop from the old to the new phase error signal, the loop remains locked and switching is hitless.

Abstract: A PLL includes an oscillator, a time-to-digital converter (TDC) and a system for the remaining functionality. The TDC measures the oscillator's phase against a reference clock. The measured phase has an integer part obtained from a modulus-K counter, and a fractional part measured by a fine TDC. The system compares the measured phase with a desired phase, and filters it to obtain a parameter that controls the oscillator frequency. The TDC may also include a synchronization block to align the fine TDC and a pulse hider to reduce the power used by the fine TDC. The system may include an integrator to calculate the integer part of the desired phase, a second integrator to calculate the fractional part, and an interpolator for an even finer fraction. A method to obtain fast lock includes using the phase error rate of change to control the oscillator frequency.

Abstract: A PLL includes an oscillator, a time-to-digital converter (TDC) and a system for the remaining functionality. The TDC measures the oscillator's phase against a reference clock. The measured phase has an integer part obtained from a modulus-K counter, and a fractional part measured by a fine TDC. The system compares the measured phase with a desired phase, and filters it to obtain a parameter that controls the oscillator frequency. The TDC may also include a synchronization block to align the fine TDC and a pulse hider to reduce the power used by the fine TDC. The system may include an integrator to calculate the integer part of the desired phase, a second integrator to calculate the fractional part, and an interpolator for an even finer fraction. A method to obtain fast lock includes using the phase error rate of change to control the oscillator frequency.

Abstract: A PLL includes an oscillator, multiple time-to-digital converters (TDCs) and a system for the remaining functionality. The TDCs measure the oscillator's phase against respective multiple reference clocks. The system compares the respective measured phases with respective desired phases to obtain phase error signals. One is selected to close the loop. The others are monitored and adjusted when not equal to zero. When a new reference clock must be used, the loop is changed from including the old phase error signal to the new. The old phase error was zero because the loop was in lock, the new phase error is zero because it was monitored and adjusted. Therefore, upon switching the loop from the old to the new phase error signal, the loop remains locked and switching is hitless.

Abstract: A fabric for delaying digital signals in continuous time has an array of node filters. Inputs of filters in the first column are inputs of the fabric. A node filter has a delay element and a cross-coupling element, whose output signals are added or subtracted to form an output signal of the filter. A node filter in a row is concatenated to the previous filter in the row through its delay element. Inputs of cross-coupling elements are connected to other rows of the array. Outputs of node filters form the outputs of the fabric. Delay times of delay elements and cross-coupling elements are nominally equal. Drive strengths of cross-coupling elements may be lower than drive strengths of delay elements. A delay line is constructed by combining a phase generator and a fabric, where the phase generator splits a digital input signal in multiple incrementally delayed versions for the fabric inputs.