Topics: Operational amplifier, Electronic amplifier, Operational amplifier applications Pages: 2 (481 words) Published: December 3, 2013
Figure 7-10

A peak detector circuit is a series of diodes and op amps (operational amplifier) connected with capacitor in series fashion to store and hold the peak values given by voltage supply. This circuit will store the highest value or peak value of the given voltage or hold the last given peak voltage to the circuit from the voltage supplier. Peak detector converts the Ac voltage to DC voltage and reduces the disturbance. The function can be explained as follow. The capacitor stores the current peak voltage. If the input voltage is larger, the op-amp output goes positive until the capacitor is charged up to the new peak value. If the input voltage is smaller, the diode keeps the capacitor from being discharged. This peak value of voltage that is stored on the capacitor will remain until this capacitor is discharged by a mechanical or electronic switch. Components of peak detector circuit

Peak detector circuit consist of two operational amplifiers (op amps), by first op amps on diode Dn is connected in parallel manner and another diode Dp is connected in series manner. And this op amp is connected to the voltage supply. Another op amp and capacitor is connected with this circuit in series. A reset switch is added to the circuit by which the value of peak value that is stored on capacitor A resistor is connected between two op amps. When choosing the resistor, the limits must be considered: rdf τ2 >> 1/fc, where fm is the modulation Frequency and fc is the carrier frequency.

Working of peak voltage circuit:
The typical peak detector uses voltage amplifiers and a diode or an emitter follower to charge the hold capacitor, CH, unidirectional. The diode conducts positive half cycles, charging the capacitor to the peak voltage value. When the input waveform falls below the DC peak voltage value stored on the capacitor, the diode is reverse biased, blocking current flow from capacitor back to the source. Initially the...
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