mV/ac to V/dc converter IC

Hello Jan,

Did you look at Analog Devices?

Regards, Joerg

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

. . . RRIO . |\\ . >-----|+\\ . | >-----+->

. .--|-/ | . | |/ | . | | . '-----------' . .

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

say

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

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.

??? 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.

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

"J.Koning" a écrit dans le message de news:43d2817a$2$11076$ snipped-for-privacy@news.xsall.nl...

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.

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Thanks,
Fred.

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.

Hello Jan,

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

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

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

How about this:

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

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kensmith@rahul.net   forging knowledge

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

The Analog Devices Parametric Evaluation Tool goes berserk over that application. Here are other circuits you can consider: