Ring Modulators

[Don Tillman]

   Date: Fri, 15 Nov 1996 13:25:15 +0200
   From: Kimmo Koli <kimmo at clara.hut.fi>

   I think the name ring-modulator comes from earlier diode-bridge
   frequency mixers 

Yes, exactly.

   Date: Fri, 15 Nov 1996 11:41:54 +0000 (GMT)
   From: "john.." <jat5 at york.ac.uk>

   Oh good, that means that I can use half of an LM13700 as a ring modulator
   (as in the National Semiconductor data book)

Why would you want to do that?  Yeah, it'll work, but I think you'll
find a Gilbert style device to work a lot better.  

The LM13700 circuit is just a variable gain amp (2-quadrant
multiplier) with some of the original signal subtracted.  This means
that any nonlinearities in the variable gain amp will show up as
seriously distorted feedthrough. 

   From: Kimmo Koli <kimmo at clara.hut.fi>
   Date: Fri, 15 Nov 1996 15:11:57 +0200 (EET)

   why not use two LM13700 to make four four-quadrant multipliers.
   If the linearisation diodes are used then the four-quadrant operation
   works independent of temperature unlike the 3080 multiplier.

That's better.  It's also nice that the LM13700 OTAs come as a matched
pair.  

   From: JH4-man
   Date: Fri, 15 Nov 96 12:55:00 PST

   Does anybody know why they still manufacture the 1496,
   but not the linearized 1495 ?? Just wondering ...

Huh?  Is that true?  Can't be!  That's horrible!  Surely *somebody*
must make them.

   Date: Fri, 15 Nov 1996 06:32:10 -0600
   From: majmoog at synthfool.com (Kevin Lightner)

   What are the differences between 1494, 1495, 1496, 1595, etc?

1496: Basic parts you need to build a Gilbert multiplier.

1495: A 1496 with an extra diff-amp thingie to both make it more
linear and avoid that potentially annoying level shifting you need to
do to bias the upper transistors.

1494: A 1495 with a built-in voltage regulator and a differential
current converter circuit for the output.  (Ie., the output is a
single-ended current to ground instead of a differential pair of
currents to Vcc.)

The 15xx IC numbers are military temperature versions of the 14xx
numbers. 

  -- Don