Question 13 on analog electronics from GATE (Graduate Aptitude Test in Engineering) 2012 Electronics and Communication Engineering paper.
Q13. The diodes and the capacitors in the circuit shown are ideal. The voltage across the diode is
The first half of the circuit is a negative clamper circuit and the second half is a peak detector circuit as shown in the figure below.
(Discussed in Section 3.8 of MicroElectronic Circuits Sedra/Smith (from Amazon.com, from Flipkart.com) or in Chapter 6.17 of Millman’s Electronic Devices and Circuits (from Amazon.com, from Flipkart.com)
The negative clamper circuit works as follows :
The diode D1 will be initially conducting till the voltage across the capacitor C1 is charged to the peak voltage of 1 volts. In the following cyclesDuring the first half of the +ve cycle, the diode D1 will be ON and the capacitor is charged to peak voltage. The diode D1 will remain OFF during the further cycles and the voltage is given by,
The second half of the circuit i.e the peak detector circuit, provides a negative voltage of -2 volts at the output of capacitor C2. Anyhow, given that we are only interested in the output of the negative clamper, the voltage is
Based on the above, the right choice is (A) 1
 GATE Examination Question Papers [Previous Years] from Indian Institute of Technology, Madras http://gate.iitm.ac.in/gateqps/2012/ec.pdf
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