Peak Detector Circuit Explained

In this video, the peak detector circuits have been explained.

By watching this video you will learn the following topics:

0:20 How to Design the peak detector circuit (Using Diode and capacitor) and its working

2:29 Precision peak detector Circuit

3:05 Effect of load on the peak detector circuit

4:26 Precision peak detector Circuit with Buffer

5:16 Modified Peak detector circuit for the fast signals (High-Speed Peak Detector)

What is a peak detector circuit:
The peak detector circuit is used to measure the peak value of the signal.

The simple peak detector circuit can be designed using the diode and capacitor. But because of the voltage drop across the diode, this circuit will not measure the peak value of the signal accurately.

To measure the peak value of the signal accurately, precision peak detector (active peak detector) circuit is used.

Precision Peak Detector:
In Precision peak detector circuit, super diode or precision diode is used instead of the normal signal diode.
And the capacitor is connected to the output of the super diode.

Effect of load on the peak detector circuit:

Ideally, the capacitor of the peak detector should hold the peak voltage of the signal. But because of the finite load across the capacitor, the capacitor will get discharged through the load. And gradually the voltage held by the capacitor will reduce.

To, minimize the discharging of the capacitor the RC time constant should be very large (At least 10 times more than the time period of the signal)

And the best practice is to use the buffer circuit before connecting the peak detector circuit to some other circuit.

Modified Precision Peak Detector circuit for fast signals:

The precision peak detector will not work at high frequency. Because when the diode becomes reversed biased, the op-amp goes into the negative saturation. And that restricts the operating frequency range of the circuit. Using a modified circuit, it can be used for the fast signal as well.
For very fast signal, Schottky diodes are used instead of signal diodes.

This video will be helpful to all students of science and engineering in understanding the working of the peak detector and the precision peak detector circuit.

#PeakDetector
#ActivePeakDetector

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Music Credit:

[ALLABOUTELECTRONICS]

The timestamps for the different topics covered in the video:

0:20 How to Design the peak detector circuit (Using Diode and capacitor) and its working

2:29 Precision peak detector Circuit

3:05 Effect of load on the peak detector circuit

4:26 Precision peak detector Circuit with Buffer

5:16 Modified Peak detector circuit for the fast signals (High-Speed Peak Detector)

[nirbhayparmar]

Our professor often suggests your video instead of any books. Thank you for such a good content.

[noweare]

Circuit design is not easy, takes a lot of experience. Programming much easier. Great video. Your the best!

[lindsay]

Good explanation. It could be even clearer if you avoid anticipatory...
pauses just before the last word in the...
op amp. ;-)

[benjaminsmus]

Why would you dislike this!!!!
Its amazing!!!!

[sayalikathore]

Your written notes in the description make your channel unique and different

[rajababu.n]

sir i have a doubt, in the modified peak detector circuit diode d2 is not in the voltage follower loop then how it can work as a super diode. kindly clarify

[guhanrajasekar]

Could anyone explain how at 7:24, the output voltage of the circuit becomes equal to the inverting terminal input of the first op-amp? If they are equal wouldn't R be acting like a short?

[arnabbhattacharyya]

If we connect the input voltage to the inverting terminal of the opamp, and connect the feedback Path to the non-inverting terminal of the opamp, will the output peak lie in the negative y-direction???

[Siamg-bb]

6:58 why D1 is reverse biased while D2 is forward biased? Last video you taught us the opposite of this. when Vin>0 D1 was conducting while D2 is not conducting. whats the difference now? why didn't you explain it?

[uber-jaianada]

thank you, this circuit works great! And for some reason I had better results without the feedback resistor.

[saivikram]

Good expert in subject please upload more videos in electronics

[marie-paulesakr]

When D1 is FB and D2 is RB (Vin <Vpeak stored in the capacitor), Vout will be equal to Vc (last peak voltage stored by capacitor) because of the buffer stage . However, since D1 is conducting, and V+=V- =Vin. So one side of resistance R is connected to vin and the other is connected to Peak voltage. Can you explain how this works? will it affect Vout?

[ra_nyk]

One doubt in last circuit capacitor charge is equal to peak voltage - diode drop right??

[luckytech]

Sir one question ..which was asked in my barc interview..its not related to exactly this ckt but somewhat related concept. .how the current can go inside opamp from output side..means if suppose diode is ideal in above ckt and if current is supposed to go inside opamp then how it will go...is it possbl fr current to go inside opamp from output terminal( m not considering input side of opamp for above questn)

[salmafahmy]

can you help me on this problem "Design and implementation of Metal detector Circuit based on op-amp"

[ದೇವರಾಜ-ಱದ]

Sir diode resistor capacitor value tell me

[BetterCallHardik]

8:56 op amp operates in open loop @ Vin slightly positive making op amp go to +Vsat it isnt detecting peaks

[neerajhebbar]

Sir when u connected the buffer the capicitors holds the voltage for more time because of high impedence of op amp what about the fast responce of the capacitor to the input voltage how did you resolve it

[abdulziyan]

Can you make a vedio on half wave peak detector using pnp transistor