An exemplary system includes a photodetector configured to generate a plurality of photodetector output pulses over time as a plurality of light pulses are applied to and scattered by a target, a TPSF generation circuit configured to generate, based on the photodetector output pulses, a TPSF representative of a light pulse response of the target, and a control circuit configured to direct the TPSF generation circuit to selectively operate in different resolution modes.

A ring oscillator includes a chain of logic components. A storage element is associated with each logic component and configured to store a state of an output of the logic component to which the storage element is associated. A first circuit counts state transitions of an output of a given logic component of the chain. A second circuit synchronizes each storage with a clock signal. A third circuit determines a number of logic components crossed by a state transition between two edges of the clock signal. This determination is made based on the counted number of state transitions and on the stored states of the outputs.

A method of determining a phase misalignment between a first signal generated from a first signal path and a second signal generated from a second signal path may include obtaining multiple samples of the first signal proximate to when the first signal crosses zero wherein the first signal can be approximated as linear; obtaining multiple samples of the second signal proximate to when the second signal crosses zero wherein the first signal can be approximated as linear; based on the multiple samples of the first signal, approximating a first time at which the first signal crosses zero; based on the multiple samples of the second signal, approximating a second time at which the second signal crosses zero; and determining the phase misalignment between the first signal and the second signal based on a difference between the first time and the second time.

A method for estimating jitter of a clock signal includes generating a phase-adjusted clock signal based on an input clock signal and a feedback clock signal using a frequency-divided clock signal. The method generating N digital time codes for each phase adjustment of P phase adjustments of the phase-adjusted clock signal using a reference clock signal. Each digital time code of the N digital time codes corresponds to a first edge of a clock signal based on the frequency-divided clock signal. P is a first integer greater than zero and N is a second integer greater than zero. The method includes generating a jitter indicator based on an expected period of the clock signal and the N digital time codes for each phase adjustment of the P phase adjustments.

A method for predicting an operation parameter of an integrated circuit includes the following steps. A plurality of cells used by the integrated circuit are provided. A voltage-frequency sweep test is performed on each of cells through a test model to generate a plurality of parameters, wherein the parameters correspond to a voltage value. A lookup table is established according to the parameters. A timing signoff corresponding to the integrated circuit is obtained. A timing analysis is performed on a plurality of timing paths of the integrated circuit according to the timing signoff and the parameters of the lookup table to obtain a critical timing path, and the operation parameter of the integrated circuit is predicted according to the critical timing path.

Various devices, methods and systems are provided for aging-sensitive chip authentication. In one example, among others, a chip includes a reference Schmitt trigger ring oscillator (STRO) configured to enter a sleep mode during operation of the chip; a stressed STRO; a VDD charge pump configured to boost a positive voltage supplied to the stressed STRO during operation of the chip; and/or a GND charge pump configured to under-drive a ground voltage supplied to the stressed STRO during operation of the chip. In another example, a method includes detecting activation of a chip including a reference STRO and a stressed STRO and, in response to the activation of the chip, initiating sleep mode operation of the reference STRO. In response to the activation of the chip, a VDD voltage supplied to the stressed STRO can be boosted and/or a GND voltage supplied to the stressed STRO can be under-driven.

Obtaining a periodic test signal, sampling the periodic test signal using a sampling element according to a sampling clock to generate a sampled periodic output, the sampling element operating according to a supply voltage provided by a voltage regulator, the voltage regulator providing the supply voltage according to a supply voltage control signal, comparing the sampled periodic output to the sampling clock to generate a clock-to-Q measurement indicative of a delay value associated with the generation of the sampled periodic output in response to the sampling clock, generating the supply voltage control signal based at least in part on an average of the clock-to-Q measurement, and providing the supply voltage to a data sampling element connected to the voltage regulator, the data sampling element being a replica of the sampling element, the data sampling element sampling a stream of input data according to the sampling clock.

A semiconductor integrated circuit (IC) comprising a signal path combiner, comprising a plurality of input paths and an output path. The IC comprises a delay circuit having an input electrically connected to the output path, the delay circuit delaying an input signal by a variable delay time to output a delayed signal path. The IC may comprise a first storage circuit electrically connected to the output path and a second storage circuit electrically connected to the delayed signal path. The IC comprises a comparison circuit that compares outputs of the signal path combiner and the delayed signal, wherein the comparison circuit comprises a comparison output provided in a comparison data signal to at least one mitigation circuit.

A chip health monitor includes a processor configured to operate as a state machine based on instructions stored in a storage device. The state machine is configured to exercise a signal path in a chip in response to a condition and determine presence of an error in the signal path based on results from the exercise. The state machine is configured to compensate for the error by changing at least one operational parameter of the chip.

In certain aspects, a clock generator includes a ring oscillator including an input and an output. The clock generator also includes a count circuit including an input and an output, wherein the input of the count circuit is coupled to the output of the ring oscillator. The clock generator also includes a comparator including a first input, a second input, and an output, wherein the first input of the comparator is configured to receive a first count value, and the second input of the comparator is coupled to the output of the count circuit. The clock generator further includes a shift register including a shift control input and an output, wherein the shift control input is coupled to the output of the comparator, and the output of the shift register is coupled to the input of the ring oscillator.