Transition-code based linearity test method for pipelined ADCs with digital error correction

A transition-code based method is proposed to reduce the linearity testing time of pipelined analog-to-digital converters (ADCs). By employing specific architecture-dependent rules, only a few specific transition codes need to be measured to accomplish the accurate linearity test of a pipelined ADC. In addition, a simple digital Design-for-Test (DfT) circuit is proposed to help correctly detect transition codes corresponding to each pipelined stage. With the help of the DfT circuit, the proposed method can be applied for pipelined ADCs with digital error correction (DEC). Experimental results of a practical chip show that the proposed method can achieve high test accuracy for a 12-bit 1.5-bit/stage pipelined ADC with different nonlinearities by measuring only 9.3% of the total measured samples of the conventional histogram based method.