precision rectifier

Discussion in 'General Electronics Discussion' started by PRIYADHARSHINI, Feb 6, 2014.

137
8
Feb 6, 2014
what is the purpose of using precision rectifier in ADC to convert ac to DC? insteaD OF PRECISION RECTIFIER we can use normal rectifier to convert ac to Dc.

2. (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,501
2,841
Jan 21, 2010
What is the difference between a "rectifier" and a "precision rectifier"? And therein lies the explanation.

137
8
Feb 6, 2014
rectifier circuit we use a DioDe for rectification.anD in precision rectifier we use a opamp with DioDes.anD precision rectifier which has a fast forwarD voltagee Drop such that it can conDuct before 0.7v.i posteD WHAT I HAD KNOWN.

137
8
Feb 6, 2014
is it correct or not ?can you give the explanation

5. (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,501
2,841
Jan 21, 2010
A precision rectifier has zero voltage drop

137
8
Feb 6, 2014
k.but in my circuit i useD a precision rectifier.but it proDuce the output with reDuceD negative voltage.

Last edited: Feb 6, 2014

137
8
Feb 6, 2014
k.but in my circuit the precision rectifier gives the output with reDuceD negative voltage.what is the reason for this?

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8. Harald KappModeratorModerator

11,986
2,808
Nov 17, 2011
This is not a good circuit for a precision full wave rectifier.
For positive input voltages the output follows V1 via the bypass resistor R1. Any load on the output will reduce the output voltage.
For negative input voltages the rectifier via U1 is active with a gain of 2 (R3(R2). Settting R3=R2 sets gain=1. Then the output is much more symmetrical, but not identical in both half waves if you add a load. Without load it is nearly ideal.

Look here for a discussion of the different types of active rectifier.

Last edited: Feb 6, 2014