Posted on Mar 1, 2013 5171
The high-speed peak detector uses a highly accurate, fast s/h amplifier controlled by a highspeed comparator. The s/h amplifier holds the peak voltage, until the comparator switches the amp to its sample mode, to capture a new, higher voltage level. The circuit handles all common-wave shapes and exhibits 5% accuracy from 50 Hz to 2 MHz. The comparator`s output decreases when the input signal exceeds the value of the currently held output.
This transition puts the s/h amplifier into sample mode. Once the output reaches the value of the input, or the input signal falls below the output"s level, the comparator"s output increases; the high output brings the s/h amplifier back to the hold mode, thereby holding the peak value of the input signal. Reset the circuit by lowering the value of pin 4 of the NE522 comparator, which in tum allows the NE5060 s/h amplifier to acquire the input. The NE522 comparator has an open-collector output.