From: Jim Thompson
Subject: Re: How does a mixer work?
References: <firstname.lastname@example.org> <email@example.com>
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Date: Thu, 17 Oct 2002 15:09:46 GMT
NNTP-Posting-Date: Thu, 17 Oct 2002 11:09:46 EDT
Organization: Cox Communications
On 17 Oct 2002 08:05:59 -0700,
SNIPrf_man_frTHIS@yahoo.com (Frank Raffaeli),
In Newsgroup: sci.electronics.design,
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!
|> 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?
|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).
|Frank W. Raffaeli
| 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 |
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