Fault diagnosis of differential and single stage amplifier utilizing combined effect of gain and phase of output voltage

The main aim of this paper is fault testing of analog integrated circuits by simultaneous analysis of the gain vs frequency and phase vs frequency between faulty and fault free circuits. For the analysis, differential amplifier and single stage amplifier have been used as no work has been done for fault detection and localization of circuits containing BJTs analog ITC'97 benchmark circuits. The value of gain and phase of output voltage is plotted against frequency for fault free and faulty circuits. Then the obtained values and waveforms of these two circuits are compared to calculate error and detect faults. Then a combined effect has been applied in conjunction with gain and phase waveforms of faulty and fault free circuits to improve the detectability of fault. Thus an effectual, adept and reliable technique for fault testing has been developed. Moreover, group formation and signature dictionary method is also employed for successful identification and localization of faults. This entire method has been evaluated and scrutinized by manipulating simulation result of HSPICE with MATLAB program.