A BUILT-IN SELF-TEST FOR ADC AND DAC IN A SINGLE-CHIP SPEECH CODEC

Built-in self-test (BIST) has been applied to test an analog to digita l converter (ADC) and a digital to analog converter (DAC) embedded in a DSP-core ASIC. The eight performance characteristics of the ADC and the DAC designed in accordance with the ITU-T recommendations are meas ured using the BIST. Three of the eight characteristics - the attenuat ion/frequency distortion, the variation of gain with input level, and the signal-to-total distortion - have been evaluated and the measured results have shown good agreement with measured results by conventiona l tests. In the BIST operation, the DSP-core generates input stimulus and analyzes output response by control of the self-test program. The sizes of the self-test program and coefficient data are 822 words of t he IROM and 384 words of the data ROM, respectively. This area overhea d is less than 0.5% of total chip area. Test-time by the BIST is reduc ed to approximately 3.2 seconds, which is one-tenth that of convention al testing. The mixed-signal DSP-core ASIC is testable with only logic test equipment. and as a result, test-cost - that is test investment and test-time - is reduced compared with conventional test methods.