A multiple operating-mode comparator system can be useful for high bandwidth and low power automated testing. The system can include a gain stage configured to drive a high impedance input of a comparator output stage, wherein the gain stage includes a differential switching stage coupled to an adjustable impedance circuit, and an impedance magnitude characteristic of the adjustable impedance circuit corresponds to a bandwidth characteristic of the gain stage. The comparator output stage can include a buffer circuit coupled to a low impedance comparator output node. The buffer circuit can provide a reference voltage for a switched output signal at the output node in a higher speed mode, and the buffer circuit can provide the switched output signal at the output node in a lower power mode.

A multiple operating-mode comparator system can be useful for high bandwidth and low power automated testing. The system can include a gain stage configured to drive a high impedance input of a comparator output stage, wherein the gain stage includes a differential switching stage coupled to an adjustable impedance circuit, and an impedance magnitude characteristic of the adjustable impedance circuit corresponds to a bandwidth characteristic of the gain stage. The comparator output stage can include a buffer circuit coupled to a low impedance comparator output node. The buffer circuit can provide a reference voltage for a switched output signal at the output node in a higher speed mode, and the buffer circuit can provide the switched output signal at the output node in a lower power mode.

A digitally controlled delay line (DCDL) includes an input terminal, an output terminal, and a plurality of stages configured to propagate a signal along a first signal path from the input terminal to a selectable return stage of the plurality of stages, and along a second signal path from the return stage of the plurality of stages to the output terminal. Each stage of the plurality of stages includes a first inverter configured to selectively propagate the signal along the first signal path, a second inverter configured to selectively propagate the signal along the second signal path, and a third inverter configured to selectively propagate the signal from the first signal path to the second signal path. Each of the first and third inverters has a tunable selection configuration corresponding to greater than three output states.

A comparator circuit according to this embodiment includes: a comparator element configured to output a matching signal indicating whether or not a value of a first input signal matches a value of a second input signal; a flip-flop circuit configured to hold a data of a data input terminal based on a comparator clock signal and configured to output an enable signal for stopping an operation of the comparator element; and an internal signal generation circuit configured to output an internal signal to the data input terminal based on the matching signal and an output signal output from the flip-flop circuit.

A comparator circuit according to the present embodiment: including a comparator element configured to output a matching signal indicating whether or not a value of a first input signal matches a value of a second input signal; a flip-flop circuit including a data input terminal to which a constant potential is supplied and a clock input terminal and configured to hold a value of the data input terminal based on a self-clock signal input to the clock input terminal; and a clock generation circuit configured to generate the self-clock signal based on the matching signal.

Analog calibration (ACAL) circuits supporting iterative measurement of an input signal from a measured circuit, and related methods are disclosed. The ACAL circuit includes a voltage reference generation circuit and a comparator circuit. The voltage reference generation circuit is configured to provide an input reference voltage. The comparator circuit is configured to compare the input reference voltage to an input circuit voltage of a measured circuit and generate a digital measurement signal based on the comparison. To provide for the ACAL circuit to more precisely measure the input circuit voltage, the voltage reference generation circuit is programmable and is configured to a generate the input reference voltage based on a programmed reference voltage selection. In this manner, the ACAL circuit can be used to measure the input circuit voltage in an iterative manner based on different programmed input reference voltages for a more precise measurement of the input circuit voltage.

Analog calibration (ACAL) circuits supporting iterative measurement of an input signal from a measured circuit, and related methods are disclosed. The ACAL circuit includes a voltage reference generation circuit and a comparator circuit. The voltage reference generation circuit is configured to provide an input reference voltage. The comparator circuit is configured to compare the input reference voltage to an input circuit voltage of a measured circuit and generate a digital measurement signal based on the comparison. To provide for the ACAL circuit to more precisely measure the input circuit voltage, the voltage reference generation circuit is programmable and is configured to a generate the input reference voltage based on a programmed reference voltage selection. In this manner, the ACAL circuit can be used to measure the input circuit voltage in an iterative manner based on different programmed input reference voltages for a more precise measurement of the input circuit voltage.

Methods, systems, and devices for signal sampling with offset calibration are described. For example, sampling circuitry may include an input pair of transistors where input signals may be provided to gate nodes of the transistors, and an output signal may be generated based on a comparison of voltages of drain nodes of the transistors. In some examples, source nodes of the transistors may be coupled with each other, such as via a resistance, and each source node may be configured to be coupled with a ground node. In some examples, a conductive path between the source nodes may be coupled with one or more switching components configurable for further coupling of the source nodes with the ground node. In some examples, enabling such switching components may add an electrical characteristic (e.g., capacitance) to the conductive path between the source nodes, which may be configurable to mitigate sampling circuitry imbalances.

A test method is provided to test a semiconductor integrated circuit including an analog-to-digital converter and/or a digital-to-analog converter. An analog test signal having a test pattern is generated using an analog test signal generator or a digital test signal having the test pattern using a digital test signal generator. An analog output signal corresponding to the test pattern is generated by applying, as a digital input signal, the digital test signal having the test pattern to a digital-to-analog converter responsive to generation of the digital test signal. A digital output signal corresponding to the test pattern is generated by applying, as an analog input signal, the analog test signal having the test pattern or the analog output signal corresponding to the test pattern to an analog-to-digital converter. A normality of the semiconductor integrated circuit is determined based on the digital output signal corresponding to the test pattern.

A test method is provided to test a semiconductor integrated circuit including an analog-to-digital converter and/or a digital-to-analog converter. An analog test signal having a test pattern is generated using an analog test signal generator or a digital test signal having the test pattern using a digital test signal generator. An analog output signal corresponding to the test pattern is generated by applying, as a digital input signal, the digital test signal having the test pattern to a digital-to-analog converter responsive to generation of the digital test signal. A digital output signal corresponding to the test pattern is generated by applying, as an analog input signal, the analog test signal having the test pattern or the analog output signal corresponding to the test pattern to an analog-to-digital converter. A normality of the semiconductor integrated circuit is determined based on the digital output signal corresponding to the test pattern.