Re: What's inside an analog 4-quadrant multiplier?

From: Winfield Hill (hill_a_at_t_rowland-dotties-harvard-dot.s-edu)
Date: 01/05/05 

Date: 5 Jan 2005 05:26:43 -0800

Stephan Goldstein wrote...
>
>>>> Tim Shoppa wrote:
>>>>>
>>>>> The data sheets for analog 4-quadrant multiplier-on-a-chip chips are
>>>>> remarkably vague as to what goes on inside the chip. I'm thinking
>>>>> specifically of the Analog Devices AD633 and the Burr-Brown MPY634,
>
> I looked around in my files yesterday and couldn't find anything
> specific to the innards of the AD633. But the basic principles of
> a 4-quadrant multiplier are in ADI's _Nonlinear Circuits Handbook_
> -- basically, make two 2-quadrant multipliers and tie them together.
> It's a little more than this, of course, but that's the general idea.
>
> These multipliers are translinear circuits, not logarithmic ones, so
> the thermal issues that always arise with loggers are not a problem.

 There's lots of good detail in Barrie Gilbert's patents, including
 his very effective linearizer secrets, with schematics and full math.

 4,156,283 - Multiplier Circuit
 4,586,155 - High-Accuracy Four-Quadrant Multiplier Which is
                 Capable of Four-Quadrant Division
 6,074,082 - Single-Supply Analog Multiplier

 Another good info source is Barrie's two lengthy chapters in the book,
 "Analogue IC Design: The Current-Mode Approach," edited by C. Toumazou. 

-- 
 Thanks,
    - Win
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