Cost/benefit analysis of the P1149.4 mixed-signal test bus

After briefly describing the proposed IEEE P1149.4 mixed-signal test bus standard and its salient benefits, the author investigates detailed costs of implementing the standard on ICs. The benefits include continuous time access in voltage and current mode, measurement of parameters such as resistance, capacitance and delay, and true differential access. The cost increase can vary between 3 and 35%, depending on the initial die size and whether 1149.1 is already on the IC. Lastly, proposed alternatives and future acceptance are discussed