[sdiy] Noninverting precision half-wave rectifier?

[Jerry Gray-Eskue]

Try this:

V1-RRR--+-----RRR--------------+--------> Vout Inverting
        |                      |
        +--|<|----------+--|<|--
        |               |
        +-|(-)          |
          |op amp-------+--> Vout Non Inverting
        +-|(+)
        |
        V2

RRR   = resistors
-|<|- = Diode cathode on left

V1 and V2 signal and ground these can be used either signal to - in or
signal to + in.

V1 signal in look at Vout Non Inverting
V2 signal in look at Vout Inverting

If you have the books:

Part of the Full Wave rectifier Figure 7-9 pg 141 - Shows + input
Operational Amplifiers and Linear Integrated Circuits - Coughlin/Driscol 2nd
edition


Figure 10.4 Pg 589 Analysis and Design of Analog Integrated Circuits -
Gray/Meyer 2nd edition
Shows - input

- Jerry

-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl
[mailto:synth-diy-bounces at dropmix.xs4all.nl]On Behalf Of David G. Dixon
Sent: Saturday, September 26, 2009 12:59 AM
To: 'Synth-DIY DIY'
Subject: [sdiy] Noninverting precision half-wave rectifier?


Most of you are probably aware of the inverting precision half-wave
rectifier (inverting opamp with two artfully placed diodes).  Well, I'm
looking this old book "Handbook of Operational Amplifier Circuit Design",
and it's also got a schematic of a NON-inverting precision half-wave
rectifier (Fig. 16.6 on page 16-6).  It is basically the non-inverting
analogue of the inverting rectifier.  I'm thinking, "Wow, this is great: an
active rectifier with high input impedance which isn't severely slew-rate
limited.  Why haven't the other books mentioned this great circuit?!?"
However, when I simulate it in Multisim, it doesn't rectify.

There isn't really any such thing, is there?  Only the crappy, severely
slew-rate limited one-diode version which Horowitz and Hill warns us against
(but which I've used on several occasions anyway).  The book is wrong.

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