Any low power low frequency quadrature receivers?

While looking at a single sideband receiver project that may be coming up I checked the usual suspects for quadrature demodulators. Many won't (technically ...) go much below 100MHz. Some do and I need to be more in the 5-10MHz region. But they are massive guzzlers when it comes to draining the battery. Like this one which slurps a whole watt (!):

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Isn't there anything better out there that hasn't been discontinued? Or do I have to roll my own again?

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg
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something like this?:

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-Lasse

Reply to
langwadt

Hell... these days, it's more like... ADC, Hilbert transform, lowpass filter. And it'd probably come out way less than a watt. That's kind of sad.

Tim

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Reply to
Tim Williams

products/product.html

190mW still isn't super low -- but it's an impressive part.
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Reply to
Tim Wescott

Perhaps, but the following FPGA and/or high-performance DSP will probably suck down plenty-o-power (and space). It'd be interesting to check, though.

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Tim Wescott
Control system and signal processing consulting
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Reply to
Tim Wescott

If you have access to the clock, actually 4x the clock, the demod can be quite simple. Split the sample stream in half, then with those two streams, alternately multiply by -1. Then you have I and Q channels.

Reply to
miso

or, Q and I? ...nevermind.

Reply to
Robert Macy

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Yes, something like but just not at so much power consumption. This one is especially archaic. Needs a negative supply which nowadays hardly any device has (ok, I can make that) and then almost 200mW. They state it "per channel", probably so it looks better :-)

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

That's going to consume lots of real estate and power. I have a spectrum analyzer that works in a similar way but still needs 2W (which, of course, is much less then the 200-300W of a big boat anchor). The PC digs all the signals back out but after a few minutes the fans come on and stay on ...

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

I know, I've done it many times that way using discrete parts. Since the late 80's, pretty much. But that consumes lots of real estate and power. This time I don't have either.

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

You could reduce power (maybe) by using NE612 parts -- but not space, I think.

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Tim Wescott
Control system and signal processing consulting
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Reply to
Tim Wescott

Lots of patents on that scheme. It is really a pity since the scheme is totally obvious to those skilled in the art.

Reply to
miso

Come to think of it, I've done this using CMOS switches as the "mixer" -- but that was in a spot that could stand being low dynamic range, and it was at audio-ish frequencies.

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Reply to
Tim Wescott

So, are the semiconductor manufacturers really missing the boat on this, or is there really not a big market outside of a few old ex ham radio guys?

Because there does seem to be a big gap (from about 0Hz to 100MHz, in fact) for a nice, modern, small, low-power implementation of this.

Maybe all that most of the engineering world knows how to do is copy their competitor's designs, or go straight to digital.

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Reply to
Tim Wescott

dual flipflop and dual dpdt switch?

-Lasse

Reply to
langwadt

Either method is the classical one, with lots of parts and lots of rea estate. Nowadays one can get many chips in TSSOP but not all of them. A SO-package would be like a Mack truck on this board.

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

If such silly patents haven't run out all it takes is proof that you dunnit 25 years ago and ... poof ... blows it out the water.

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

I'd guess the latter. Lots of 900MHz, lots of 2.4, not a lot else...

I think the salient question is: will it end up on a box in a Frys? Even then, you're gambling the NRE...

-- Les Cargill

Reply to
Les Cargill

Sure, that's the usual way because the SA612 and others cannot be had in TSSOP whereas some CMOS muxes can. But that leaves a ton of other circuitry such as amps and such to be added.

I am just surprised that when it comes to complete quadrature demodulators on a single chip there's on Goliaths out there.

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

They are missing the whole medical and NDT market. Ok, those aren't big but very profitable. Because there you can easily sell a chip at five bucks that costs 10c in production and is simply a stripped-down version of a big one.

Often that is the case, they follow each other and sometimes blindly. There are many things in the world of ICs that IC designers or their managers fail to see. Another classic one: Switcher chips that support higher voltage designs often have an on-chip LDO that supplies the gate driver with a fixed 7V or so. Yet anyone in the trade who has designed switchers a lot knows that most FETs above 100V are not spec'd at any Vgs under 10V. So _every_ time I design such a switcher I have to backfeed the LDO output. Chips that don't have that piped out or have a shunt regulator at less than 10V are useless for such designs.

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Regards, Joerg

http://www.analogconsultants.com/
Reply to
Joerg

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