Simple Precision Half Wave Peak Detector Circuit

This is a simple circuit for half peak detector that is using transistor. This circuit is very compact and low cost, but if the application require precise detection for signal under 100mV then that circuit is become useless. In the figure below, the circuit is become precise half-wave peak detector circuit using only a single op-amp with few passive components. This is the figure of the circuit.


This peak detector circuit can be implemented both for average peak detector or a fast peak detector by selecting R2 and R3 values as shown in the table. Note that the output impedance is set by R3, so make sure that the output of this peak detector circuit will be connected to a higher impedance input stage. [Schematic diagram source: National Semiconductor Application Note]