precision full wave recitifier on a chip?

B

BobG

Guest
I've seen 3 opamp instrumentation amps on a chip.... but now I'm
looking for a 2 opamp precision rectifier full wave rectifier/absolute
value circuit on a chip.... looked for one but didnt see any... ever
heard of one?
 
Hello Bob,

What do you want to measure and from what kind of input signal? RMS to
DC or even dB can be done single chip, for example with the AD536.

Basically, if Analog Devices doesn't have a chip with a desired analog
conversion function the chances are pretty high that it doesn't exist.
But they do have a lot.

Regards, Joerg

http://www.analogconsultants.com
 
On 13 Mar 2005 17:39:51 -0800, "BobG" <bobgardner@aol.com> wrote:

I've seen 3 opamp instrumentation amps on a chip.... but now I'm
looking for a 2 opamp precision rectifier full wave rectifier/absolute
value circuit on a chip.... looked for one but didnt see any... ever
heard of one?
Click to expand...
How about this one:http://www.edn.com/article/CA296498.html?spacedesc=designideas
 
The Phantom wrote...
On 13 Mar 2005 17:39:51 -0800, "BobG" <bobgardner@aol.com> wrote:

I've seen 3 opamp instrumentation amps on a chip.... but now I'm
looking for a 2 opamp precision rectifier full wave rectifier/absolute
value circuit on a chip.... looked for one but didnt see any... ever
heard of one?
Click to expand...
Check out Analog Devices AD630 absolute-value chip.

How about this one:
http://www.edn.com/article/CA296498.html?spacedesc=designideas
Click to expand...
That circuit is more complex than the one in our book (AoE page 188).

Overly-simple active rectifier designs suffer from poor performance at
high frequencies, or at low signal levels and moderate frequencies. In
the case of Ron Mancini's design, an additional diode, D2, should be
added to prevent U1 from swinging more than a diode drop towards -5V
during each half cycle, to reduce the slew-rate-limited recovery time.

.. in
.. ---+- 10k 1% --+-- 10k 1% ----,
.. | % | D2 sd101 | improved version
.. | +---|>|-----, | of Ron Mancini's
.. | | __ | | 2003 EDN design.
.. | '---|- \ U1 | |
.. | | >---+ |
.. | gnd ---|+_/ | |
.. | D1 sd101 | |
.. '-- 4.7k ---+---|<|-----' |
.. 5% | __ |
.. '---|+ \ U2 | out
.. | >---+--+---
.. ,---|-_/ |
.. | |
.. '-----------'

In this design, U1's output has to quickly swing two diode drops during
each half cycle, and the time it takes to do this limits its performance.

At low signal levels one can't simply apply the datasheet slew-rate spec,
because that value assumes a large input error (AoE page 403-410). In
many types of advanced active-rectifier designs, the issue becomes one
of reducing the voltage swing necessary to drive any nonlinear elements
(e.g. using extra compensation or clamp pins in an opamp), or finding ways
to speed it up (e.g., higher slew rate at lower input-error voltages).


--
Thanks,
- Win
 
Winfield Hill <hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

That circuit is more complex than the one in our book (AoE page 188).
Click to expand...
Hey, so you are one of the two authors of AoE!
Wow!

--
Per rispondermi via email sostituisci il risultato
dell'operazione (in lettere) dall'indirizzo
 
On Sun, 13 Mar 2005 20:37:13 -0800, The Phantom <phantom@aol.com>
wrote:

On 13 Mar 2005 17:39:51 -0800, "BobG" <bobgardner@aol.com> wrote:

I've seen 3 opamp instrumentation amps on a chip.... but now I'm
looking for a 2 opamp precision rectifier full wave rectifier/absolute
value circuit on a chip.... looked for one but didnt see any... ever
heard of one?

How about this one: http://www.edn.com/article/CA296498.html?spacedesc=designideas
Click to expand...
Amusing. Idea dates to 1982. See my improved version as
"FullWaveRectifier.pdf" on the S.E.D/Schematics page of my website.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On 13 Mar 2005 17:39:51 -0800, "BobG" <bobgardner@aol.com> wrote:

I've seen 3 opamp instrumentation amps on a chip.... but now I'm
looking for a 2 opamp precision rectifier full wave rectifier/absolute
value circuit on a chip.... looked for one but didnt see any... ever
heard of one?
Click to expand...
See "FullWaveRectifier.pdf" on the S.E.D/Schematics page of my
website.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
On 14 Mar 2005 05:53:47 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

The Phantom wrote...

On 13 Mar 2005 17:39:51 -0800, "BobG" <bobgardner@aol.com> wrote:

I've seen 3 opamp instrumentation amps on a chip.... but now I'm
looking for a 2 opamp precision rectifier full wave rectifier/absolute
value circuit on a chip.... looked for one but didnt see any... ever
heard of one?

Check out Analog Devices AD630 absolute-value chip.

How about this one:
http://www.edn.com/article/CA296498.html?spacedesc=designideas

That circuit is more complex than the one in our book (AoE page 188).

Overly-simple active rectifier designs suffer from poor performance at
high frequencies, or at low signal levels and moderate frequencies. In
the case of Ron Mancini's design, an additional diode, D2, should be
added to prevent U1 from swinging more than a diode drop towards -5V
during each half cycle, to reduce the slew-rate-limited recovery time.

. in
. ---+- 10k 1% --+-- 10k 1% ----,
. | % | D2 sd101 | improved version
. | +---|>|-----, | of Ron Mancini's
. | | __ | | 2003 EDN design.
. | '---|- \ U1 | |
. | | >---+ |
. | gnd ---|+_/ | |
. | D1 sd101 | |
. '-- 4.7k ---+---|<|-----' |
. 5% | __ |
. '---|+ \ U2 | out
. | >---+--+---
. ,---|-_/ |
. | |
. '-----------'

In this design, U1's output has to quickly swing two diode drops during
each half cycle, and the time it takes to do this limits its performance.

At low signal levels one can't simply apply the datasheet slew-rate spec,
because that value assumes a large input error (AoE page 403-410). In
many types of advanced active-rectifier designs, the issue becomes one
of reducing the voltage swing necessary to drive any nonlinear elements
(e.g. using extra compensation or clamp pins in an opamp), or finding ways
to speed it up (e.g., higher slew rate at lower input-error voltages).
Click to expand...
Amusing. Idea dates to 1982. See my improved version as
"FullWaveRectifier.pdf" on the S.E.D/Schematics page of my website,
which I've been using since that date.

Even with mid '80's OpAmps I was able to rectify 400KHz signals
accurately.

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
I read in sci.electronics.design that The Phantom <phantom@aol.com>
wrote (in <b35a31d0m6tej6rlaust3ujs440kchhteg@4ax.com>) about 'precision
full wave recitifier on a chip?', on Sun, 13 Mar 2005:
On 13 Mar 2005 17:39:51 -0800, "BobG" <bobgardner@aol.com> wrote:

I've seen 3 opamp instrumentation amps on a chip.... but now I'm
looking for a 2 opamp precision rectifier full wave rectifier/absolute
value circuit on a chip.... looked for one but didnt see any... ever
heard of one?

How about this one:http://www.edn.com/article/CA296498.html?spacedesc=designidea
s


The LM3915 data sheet has several rectifier circuits, including a
Click to expand...
'precision full-wave peak detector' using a dual op-amp.
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
 
Thanks all. I need 8 of em to sniff 8 audio channels.. using an 8 ch
a/d avr.... I showed the standard 2 opamp fwr abs val to the layout
guy... he says... dont they have that on a chip yet.... guess he didnt
want to draw 8 of em... thought I'd ask.......
 
On 14 Mar 2005 10:01:42 -0800, "BobG" <bobgardner@aol.com> wrote:

Thanks all. I need 8 of em to sniff 8 audio channels.. using an 8 ch
a/d avr.... I showed the standard 2 opamp fwr abs val to the layout
guy... he says... dont they have that on a chip yet.... guess he didnt
want to draw 8 of em... thought I'd ask.......
Click to expand...
You and what ONE other person would buy it ?:)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Bet they said that to the guy that wanted a 3 opamp instrumentation
amplifier.
 
On 14 Mar 2005 10:01:42 -0800, in sci.electronics.design "BobG"
<bobgardner@aol.com> wrote:

Thanks all. I need 8 of em to sniff 8 audio channels.. using an 8 ch
a/d avr.... I showed the standard 2 opamp fwr abs val to the layout
guy... he says... dont they have that on a chip yet.... guess he didnt
want to draw 8 of em... thought I'd ask.......
hmm, not quite what you want but AD8307 might be worth a look
Click to expand...

martin

"An eye for an eye makes the whole world blind"
Gandhi
 
Jim Thompson wrote...
Amusing. Idea dates to 1982. See my improved version as
"FullWaveRectifier.pdf" on the S.E.D/Schematics page of my website,
which I've been using since that date.
Click to expand...
Yes, it's old... Much older than 1982.

I started using active rectifiers in 1968 or thereabouts, and we
described them for AoE in 1978. I advanced to log versions 1972.

Even with mid '80's OpAmps I was able to rectify 400KHz signals
accurately.
Click to expand...
400kHz per se isn't so tough; it's the combination of low signal
levels (as in wide dynamic-range detectors) and high frequencies
that gets difficult. I have a design that works up to 1MHz, yet
retains <1% accuracy for signals down to 0.1% of full scale, IIRC.
That was more difficult, and I had to play a few tricks with the
opamp slew distance. Fast opamps make the job easier, but often
more is required than simply plunking in a faster opamp.


--
Thanks,
- Win
 
On 14 Mar 2005 13:55:29 -0800, Winfield Hill
<hill_a@t_rowland-dotties-harvard-dot.s-edu> wrote:

Jim Thompson wrote...

Amusing. Idea dates to 1982. See my improved version as
"FullWaveRectifier.pdf" on the S.E.D/Schematics page of my website,
which I've been using since that date.

Yes, it's old... Much older than 1982.

I started using active rectifiers in 1968 or thereabouts, and we
described them for AoE in 1978. I advanced to log versions 1972.

Even with mid '80's OpAmps I was able to rectify 400KHz signals
accurately.

400kHz per se isn't so tough; it's the combination of low signal
levels (as in wide dynamic-range detectors) and high frequencies
that gets difficult. I have a design that works up to 1MHz, yet
retains <1% accuracy for signals down to 0.1% of full scale, IIRC.
That was more difficult, and I had to play a few tricks with the
opamp slew distance. Fast opamps make the job easier, but often
more is required than simply plunking in a faster opamp.
Click to expand...
I have added a copy of an article from the 11/25/82 EDN (where I first
saw the two-OpAmp FW Rectifier described) to "FullWaveRectifier.pdf"
on the S.E.D/Schematocs page of my website. (I save everything :)

Way back then, realizing the floating-summing-node problem, I marked
up the article with the extra diode.

I don't see anything resembling this configuration in AoE.

I was using active rectifiers before you were a pup ;-)

...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.
 
Jim Thompson wrote...
Winfield Hill wrote:

Jim Thompson wrote...

Amusing. Idea dates to 1982. See my improved version as
"FullWaveRectifier.pdf" on the S.E.D/Schematics page of my website,
which I've been using since that date.

Yes, it's old... Much older than 1982.

I started using active rectifiers in 1968 or thereabouts, and we
described them for AoE in 1978. I advanced to log versions 1972.

Even with mid '80's OpAmps I was able to rectify 400KHz signals
accurately.

400kHz per se isn't so tough; it's the combination of low signal
levels (as in wide dynamic-range detectors) and high frequencies
that gets difficult. I have a design that works up to 1MHz, yet
retains <1% accuracy for signals down to 0.1% of full scale, IIRC.
That was more difficult, and I had to play a few tricks with the
opamp slew distance. Fast opamps make the job easier, but often
more is required than simply plunking in a faster opamp.

I have added a copy of an article from the 11/25/82 EDN (where I first
saw the two-OpAmp FW Rectifier described) to "FullWaveRectifier.pdf"
on the S.E.D/Schematocs page of my website. (I save everything :)

Way back then, realizing the floating-summing-node problem, I marked
up the article with the extra diode.

I don't see anything resembling this configuration in AoE.
Click to expand...
I didn't say it was the same, there are probably five or six good
configurations. Our full-wave circuit is on page 221 (another is
on page 469). I prefer ours because both amplifiers have grounded
summing junctions, which is arguably better at high frequencies,
because the opamp's CMRR performance isn't put to the test.

Do you like your fixed-up EDN version better? Fewer resistors?

I was using active rectifiers before you were a pup ;-)

...Jim Thompson
Click to expand...
Maybe, that's what happens when you are older. But I'm sure there
must have been a few good circuits in the 40s and 50s using tubes.


--
Thanks,
- Win
 
See bottom of page 19.
http://www.analog.com/UploadedFiles/Data_Sheets/248354455AD8036_7_b.pdf

I've used these to clip HDTV video and as 'higher of A or B' (analog OR
function) at 30 MHz and they work great. Only quirk: Vh must always be
more positive then Vl.
GG
 
On 14 Mar 2005 19:38:08 -0800, in sci.electronics.design "Glenn
Gundlach" <stratus46@yahoo.com> wrote:

See bottom of page 19.
http://www.analog.com/UploadedFiles/Data_Sheets/248354455AD8036_7_b.pdf

I've used these to clip HDTV video and as 'higher of A or B' (analog OR
function) at 30 MHz and they work great. Only quirk: Vh must always be
more positive then Vl.
GG
AD8307 not AD8037
Click to expand...


martin

"An eye for an eye makes the whole world blind"
Gandhi
 
That is one of my worst consistent errors-- transposing digits 2 and 3
of a 4 digit sequence. BUT, the AD8036/7 does make a good fullwave
rectifier.
GG
 
Thanks folks... the 8036 does do a single chip full wave
recitifier/absolute value. Never seen one before today! (I looked at
that 8307 and was scratching my head.....)
 
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