Question

The below figure arrives to a conclusion that _________

(a) for Vi > 0, V0=-(R2/R1)Vi

(b) for Vi > 0, V0=0

(c) Vi < 0, V0=-(R2/R1)Vi

(d) Vi < 0, V0=0

The question was posed to me during an interview for a job.

This intriguing question comes from Half-Wave Rectifier topic in division Application of Diodes of Electronic Devices & Circuits

Answer 1

Correct choice is (b) for Vi > 0, V0=0

For explanation: The given op-amp is in inverting mode and this makes the output voltage to have a phase shift of 180°. The output voltage is now negative. So, the diode 1 is reverse biased and diode 2 is forward biased. Then output is clearly zero.