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From: SNIPrf_man_frTHIS@yahoo.com (Frank Raffaeli)
Subject: Re: How does a mixer work?
Date: 17 Oct 2002 20:27:03 -0700
References: <email@example.com> <firstname.lastname@example.org>
NNTP-Posting-Date: 18 Oct 2002 03:27:03 GMT
Jim Thompson wrote in message news:...
> On 17 Oct 2002 08:05:59 -0700,
> SNIPrf_man_frTHIS@yahoo.com (Frank Raffaeli),
> In Newsgroup: sci.electronics.design,
> Article: <email@example.com>,
> Entitled: "Re: How does a mixer work?",
> Wrote the following:
> |firstname.lastname@example.org (Asa Cannell) wrote in message news:<email@example.com>...
> |> How does a mixer work? I don't understand why it needs a non-linear
> |> element. I think examples of why a linear element (resistor) wont work
> |> would help illustrate why a non-linear element (diode) will. Also,
> |It doesn't need a non-linear element. Non-linear elements, like diodes
> |or over-driven transistors can provide a simple way to derive a
> |product component of two signals. For a nearly linear approach, look
> |up "Gilbert cell mixer". This uses linear elements and current
> |steering / sharing. An AC current with a DC bias is split between a
> |differential pair and steered to one side or the other by altering the
> |bias on the bases / gates of the pair.
> NAAAAAH! The "elements" ARE NOT LINEAR!
Hmm ... ok, that's true. No transistor is perfectly linear, even when
you try to operate in a linear range. I guess my point was that a
Gilbert cell multiplier works very well when operated in the linear
range of the devices, and the operation of the (Gilbert) multiplier is
not dependent upon the inherent non-linearity of the transistors.
> |> what does 'mutiply' mean in terms of mixing? What if two DC signals
> |> are applied to a mixer, like 2V and 4V? Will the output be 8V?
> |> (multiply).
> |> Thanks,
> |> Asa
> |Three more ways to multiply signals: 1) Use a multiplying DAC; 2) Use
> |a log amp and add; 3) Use a tetrode, (a solid state 'e.g. dual-gate
> |mosfet' or vacuumn tube device that has a second gate or grid).
> ALL NON-LINEAR.
> |Best Regards,
> |Frank W. Raffaeli
> ...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 | |
> | Jim-T@analog_innovations.com Fax:(480)460-2142 | Brass Rat |
> | http://www.analog-innovations.com | 1962 |
> For proper E-mail replies SWAP "-" and "_"
> I love to cook with wine. Sometimes I even put it in the food.
Frank W. Raffaeli
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