mV/ac to V/dc converter IC

[J.Koning]

I'm looking for an IC giving an output in the
range of 0-1Vdc or 0-10Vdc at an input voltage
of 0-10mV/ac with a frequency around 1MHz/sine.
Supply voltages available are +/-5V and +/-15V.
Accuracy/linearity is not that important.
I rather prefer something simple such as a
device with low external component count like
integrated rectifier diodes etc.

Can anybody help?

Rgds,
Jan.

 

[Joerg]

Hello Jan,

I'm looking for an IC giving an output in the
range of 0-1Vdc or 0-10Vdc at an input voltage
of 0-10mV/ac with a frequency around 1MHz/sine.
Supply voltages available are +/-5V and +/-15V.
Accuracy/linearity is not that important.
I rather prefer something simple such as a
device with low external component count like
integrated rectifier diodes etc.

Can anybody help?

Did you look at Analog Devices?

http://www.analog.com/en/subCat/0,2879,770%5F849%5F0%5F%5F0%5F,00.html

Regards, Joerg

 

[Fred Bloggs]

I'm looking for an IC giving an output in the
range of 0-1Vdc or 0-10Vdc at an input voltage
of 0-10mV/ac with a frequency around 1MHz/sine.
Supply voltages available are +/-5V and +/-15V.
Accuracy/linearity is not that important.
I rather prefer something simple such as a
device with low external component count like
integrated rectifier diodes etc.

Any single supply RRIO type like the AD8605:
View in a fixed-width
font such as Courier.

 

[John Jardine.]

I'm looking for an IC giving an output in the
range of 0-1Vdc or 0-10Vdc at an input voltage
of 0-10mV/ac with a frequency around 1MHz/sine.
Supply voltages available are +/-5V and +/-15V.
Accuracy/linearity is not that important.
I rather prefer something simple such as a
device with low external component count like
integrated rectifier diodes etc.

Can anybody help?

Rgds,
Jan.

I'm reading it as you wanting a 'precision rectifier'. With a gain of say
x100.
Maybe a AD636 true RMS converter, preceded by 100x ac gain opamp. Use a dc
x10 opamp to get up to a final +10Vdc.
john

 

[J.Koning]

I'm reading it as you wanting a 'precision rectifier'. With a gain of say
x100.
Maybe a AD636 true RMS converter, preceded by 100x ac gain opamp. Use a dc
x10 opamp to get up to a final +10Vdc.
john

Hi John,

There's no need for true RMS eversince my input is a true sine.
As mentioned, accuracy is NOT important, but high gain is.
So, anything simple/cheap that makes 1-10Vdc out of 10mV/1Mhz.

Rgds,
Jan

 

[J.Koning]

Hello Jan,


Did you look at Analog Devices?

http://www.analog.com/en/subCat/0,2879,770%5F849%5F0%5F%5F0%5F,00.html


Hello Joerg,

The AD630 could do the job, but eversince I do not need the
accuracy it is a bit "mit Kanonen auf Spatzen schießen".
An opamp with two suitable diodes acting as absolute
value converter followed by an integrator comes to mind.
But that again is a handfull of components I don't want.
Something cheap/small with 10mV/1Mhz in and 1-10Vdc out
and not necessarily a linear Vo=f(Vi) would be ideal.

Rgds,
Jan.

 

[J.Koning]

Any single supply RRIO type like the AD8605:
View in a fixed-width
font such as Courier.

.
.
. RRIO
. |\
. >-----|+\
. | >-----+->
. .--|-/ |
. | |/ |
. | |
. '-----------'

???
mV/ac to V/dc converter IC ???
All I see is a V-follower.
Did you read the question Fred?
Or do I miss something?

Rgds,
Jan.

 

[Fred Bloggs]

???
mV/ac to V/dc converter IC ???
All I see is a V-follower.
Did you read the question Fred?
Or do I miss something?

Rgds,
Jan.

You can put a little gain in there and drive it into an RC filter for
the smoothing. The trick is to apply the majority of gain into
amplifying a DC signal and not an ac-signal. You can do that these days
with these ultra-low Vos amps.

 

[Fred Bloggs]

???
mV/ac to V/dc converter IC ???
All I see is a V-follower.
Did you read the question Fred?
Or do I miss something?

Rgds,
Jan.

And that amp is wired between V+ and GND so its output clamps at 0.000V
under light loading on the negative input excursions.

 

[Fred Bartoli]

???
mV/ac to V/dc converter IC ???
All I see is a V-follower.
Did you read the question Fred?
Or do I miss something?

I guess you missed something. OTOH he didn't clearly tell you to supply the
opamp between GND and +5V. But if had looked at the datasheet you'll have
seen it's a 5V/single supply opamp.

But this probably won't work as such for your 1MHz signal (look at fig 27. /
1.5us recovery time).
Supplying it between -5V and GND, or having your referenced your AC signal
to the +5V supply rail will buy you a much better recovery time (see fig 26)
and might work OK.

 

[J.Koning]

1)
You can put a little gain in there and drive it into an RC filter for
the smoothing. The trick is to apply the majority of gain into
amplifying a DC signal and not an ac-signal. You can do that these days
with these ultra-low Vos amps.
2)
And that amp is wired between V+ and GND so its output clamps at 0.000V
under light loading on the negative input excursions.

OK, obviously I missed that one but now I'm with you.
Good idea, certainly for that price, I'll give it a try.

Rgds,
Jan.

 

[Joerg]

Hello Jan,

The AD630 could do the job, but eversince I do not need the
accuracy it is a bit "mit Kanonen auf Spatzen schießen".

True, it's a lot of money just for that function.

An opamp with two suitable diodes acting as absolute
value converter followed by an integrator comes to mind.
But that again is a handfull of components I don't want.

Well, it ain't that much in parts and it won't get a lot cheaper than that.

Something cheap/small with 10mV/1Mhz in and 1-10Vdc out
and not necessarily a linear Vo=f(Vi) would be ideal.

The only cheaper solution that immediately comes to mind is IF or RF
chips for radios that have an RSSI output. But this will not be a linear
function. If you are feeding this into something computerized it may not
be a problem though.

Since you are in NL Philips might be a good source for RSSI chips.

Groetjes, Joerg

 

[Ken Smith]

I'm looking for an IC giving an output in the
range of 0-1Vdc or 0-10Vdc at an input voltage
of 0-10mV/ac with a frequency around 1MHz/sine.
Supply voltages available are +/-5V and +/-15V.
Accuracy/linearity is not that important.
I rather prefer something simple such as a
device with low external component count like
integrated rectifier diodes etc.

Can anybody help?

How about this:

LM311
IN -----------! \
! \
IN------------!+ \
! ---\---- Vcc
! !/c \
! ! \
! !\e /
! ----/-----+------
---!- / ! !
! ! / \ ---
! ! / / ---
! ! / \ !
! ! GND
-------------------+
!
/
\
/
!
GND

 

[J.Koning]

How about this:

LM311
IN -----------! \
! \
IN------------!+ \
! ---\---- Vcc
! !/c \
! ! \
! !\e /
! ----/-----+------
---!- / ! !
! ! / \ ---
! ! / / ---
! ! / \ !
! ! GND
-------------------+
!
/
\
/
!
GND

Would you care for a few words of explanation?
Thanks & rgds,
Jan.

 

[Fred Bloggs]

OK, obviously I missed that one but now I'm with you.
Good idea, certainly for that price, I'll give it a try.

Rgds,
Jan.

The Analog Devices Parametric Evaluation Tool goes berserk over that
application. Here are other circuits you can consider:
http://www.discovercircuits.com/R/rectifier.htm