Programmable Josephson AC-voltages will work well for analog DFT for mixed-signal ICs under background noise even up to 20 nanovolts

Programmable Josephson AC-voltage has reached an accuracy of 10/sup -6/ at about hundreds of mv with its frequency about several tens of Hz and downwards. The nodal voltage referred to common ground to be measured for analog design-for-testability (DFT) for mixed-signal ICs ranges from several tens of mv and downwards with its frequency at about one hundred Hz and downwards. Computer simulation thus shows that analog DFT under background noise up to 20 nanovolts with programmable AC-Josephson voltage as a testing voltage will work well and moreover have good behaviour. A comparison of both optimum identification ratio of element parameters between programmable ac Josephson voltage of their lower frequency 4.375-140 Hz under background noise 1 nv, 20 nv and with signal voltage of their higher frequency 125/spl sim/4 kHz under background noise 1 nv. 10 nv is thus required. The paper gives a brief review of the idea of symbolic analysis as the op-amp type analog parts of the mixed signal IC prevail.