Programmatically generated in-circuit test of analog to digital converters
AssigneeHewlett-Packard Company
InventorWayne R. Chism
Life of this patent
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Abstract
A device and process for programmatically controlled in-circuit pin checks and gross functionality tests of analog to digital converters. The tests provide deterministic bit checks for higher order bits and non-deterministic bit checks of lower order bits independent of other circuitry on the printed circuit board of which the digital to analog converter is a component.
Claims13
A module for programmatic testing of an analog to digital converter (A/D) that is connected to components in a circuit, the module comprising:
- first voltage generator means for generating a precision direct current signal;
- second voltage generator means for generating a combined direct current and alternating current signal;
- overdriving amplifier means operatively coupled to receive the signals generated by said first and second voltage generator means for amplifying said precision direct current signal and said combined direct current and alternating current signal by an amount sufficient to isolate and stimulate said analog to digital converter from said components in said circuits;
- overdriving digital driver means for stimulating the start convert input of the analog digital converter under test for activating said analog to digital converter;
- digital receiver means for receiving a convert complete signal and measuring output data from said analog to digital converter;
- comparator means for comparing said output data with an expected response signal generated externally of said circuit;
- said testing comprising analysis of the result of the comparison of said output data with said expected response signal.
A process to programmatically perform in-circuit pin checks and gross functionality tests of analog to digital converters using overrange/underrange deterministic bit evaluation techniques comprising the steps of:
- (a) isolating an analog to digital converter to be tested in the circuit from surrounding circuitry;
- (b) applying a DC voltage above a maximum conversion range of said analog to digital converter to perform overrange test;
- (c) applying a DC voltage below a minimum conversion range of said analog to digital converter to perform underrange test;
- (d) analyzing the results of steps (b) and (c) to determine a pass/fail status of said analog to digital converter.
A process to programmatically perform in-circuit pin checks and gross functionality tests of analog to digital converters comprising the steps of:
- (a) performing a deterministic bit evaluation of high order bits by applying DC voltage to produce specific high order bit outputs of said analog to digital converter;
- (b) determining a pass/fail status of the analog to digital converter based upon said deterministic bit evaluation;
- (c) performing a non-deterministic bit evaluation of low order bits by applying specific alternating voltages to produce varying low order bit outputs of said analog to digital converter;
- and,
- (d) statistically evaluating the low order bits and determining a pass/fail status of the analog to digital converter based upon said non-deterministic bit evaluation.
Dependencies are inferred from the claim text.