Wide-range-peak-detector

Description: IC1 and IC2 form an inverting half-wave precision rectifier and peak detector circuit. Negative input signals that swing with peaks larger than the voltage on C1 cause this capacitor to charge to the new peak voltage. The capacitor retains this voltage until a larger signal peak arrives. When the input swings high, comparator IC4 detects the zero crossing and triggers the one-shot multivibrator. The one-shot closes FET switch S2, allowing C2 to charge to the peak voltage held on C1 during the previous half cycle. The second one-shot then produces a pulse that causes FET switch S1 to discharge C1. If the next negative signal input peak differs from the previous one, the circuit captures it, and it appears at IC3's output during the next half cycle. The peak detector resets itself once every input waveform cycle. It is important to note that zero crossings are necessary to trigger the switches; therefore, the circuit is only usable with AC signals.

The described circuit employs two operational amplifiers (IC1 and IC2) configured as inverting precision rectifiers, which are essential for accurately rectifying AC signals while preserving the peak values. The precision rectifier ensures that even small negative input signals can be effectively processed, allowing for high fidelity in signal capture. Capacitor C1 plays a critical role in the peak detection process, as it charges to the peak voltage of the incoming negative signal. This characteristic enables the circuit to track the highest voltage levels of the input waveform.

The comparator IC4 is integral to the operation of the circuit, as it monitors the input signal to identify zero crossings. This detection is crucial for the timing of the one-shot multivibrator, which generates a short pulse to control the FET switches. The use of FET switches S1 and S2 provides fast response times and low on-resistance, which minimizes signal distortion during switching operations.

As the input signal transitions from negative to positive, the one-shot multivibrator activates switch S2, allowing capacitor C2 to charge to the voltage level previously held on C1. This mechanism ensures that the circuit can capture and hold the peak voltage for subsequent processing. The second one-shot multivibrator triggers switch S1 to discharge C1, preparing the circuit for the next cycle of input signals.

The design emphasizes that the circuit is tailored for AC signals due to its reliance on zero crossings for switch activation. This limitation underscores the importance of understanding the waveform characteristics when implementing the circuit in practical applications. Overall, the precision rectifier and peak detector circuit is a sophisticated solution for capturing and processing AC signals, particularly in applications requiring accurate peak detection and fast response times.ICl and IC2 form an inverting half-wave precision-rectifier/peak-detector circuit. Negative input-signal, swings with peaks larger than the voltage on Cl, cause this capacitor to charge to the new peak voltage. The capacitor holds this voltage until a larger signal peak arrives. When the input swings high, comparator IC4 detects the zero crossing and triggers the one-shot multivibrator.

The one shot closes FET switch S2, thereby causing C2 to charge to the peak voltage held on Cl, during the previous half cycle. The second one shot then produces a pulse that causes FET switch Sl to discharge Cl. Ifthe next negative signal-input peak is different from the previous one, the circuit captures it and it appears at IC3"s output during the next half cycle. The peak detector thus resets itself once every input-waveform cycle. Note that the zero crossings are necessary to trigger the switches; therefore, the circuit is usable only with ac signals.