Comparator metastable state detection circuit for successive approximation analog-to-digital converter

Abstract

The invention belongs to the technical field of analog integrated circuits, and particularly relates to a comparator metastable state detection circuit for a successive approximation type analog-to-digital converter. The device comprises a metastable state detection module, a metastable state flag bit latch module, a sampling signal control switch and a delay control digital code selection module. The metastable state detection module is used for judging whether the comparator is in a metastable state or not. And the metastable state flag bit latching module latches the metastable state flag signal after each metastable state detection. And the sampling signal control switch controls the successive approximation analog-to-digital converter not to sample the input signal in the delay control digital code selection mode. And the delay control digital code selection module adopts a successive approximation mode to adjust the first delay control digital code according to the occurrence condition of the metastable state in the last two comparisons in each sampling period, so that the metastable state voltage detection voltage range of the metastable state judgment module is maintained near a least significant bit of the analog-to-digital converter.

Description

technical field [0001] The invention belongs to the technical field of analog integrated circuits, and in particular relates to a comparator metastability detection circuit for successive approximation analog-to-digital converters. Background technique [0002] The metastable state of the comparator means that when the voltages at the two input terminals of the comparator are very close, the comparison result cannot be produced for a long time. In the field of successive approximation analog-to-digital converters, the capacitance mismatch calibration technology based on metastable state detection is widely used. A metastable state of the analog-to-digital converter is detected when one of the least significant bits is turned on. The existing metastable state detection circuit generally judges whether the comparator is metastable by a delay comparison method. The principle is to detect the state of the output signal of the comparator after a fixed period of time after the c...

AI Technical Summary

Problems solved by technology

The following problems generally exist in the existing metastable state detection circuit: First, the delay of the delay circuit in the metastable state detection circuit generally needs to be controlled by the delay control digital code input from the outside of the chip. Second, the delay of the comparator is affected by conditions such as process deviation, temperature, and power supply voltage. Changes in these conditions will cause the above method to accurately determine whether the comparator is in a metastable state. , that is, when the voltage difference between the two input terminals of the comparator is small, the metastable state detection circuit judges that it has a metastable state, or when the voltage difference between the two input terminals of the comparator is large, the metastable state detection circuit judges that it is not metastability

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