[sdiy] MC1495 multiplier chip discontinued completely

[Tim Ressel]

There is always the AD633 from Analog Devices. It's
not cheap at about $9, but most folks only need a few,
and the specs are better than the 1495.

--Tim

--- Czech Martin <Martin.Czech at Micronas.com> wrote:
> I just learned from Arrow/Spoerle that the MC1495
> multiplier chip
> is discontinued and they can not ship any more.
> On Semiconductor has accordingly made an update to
> their
> web site. 
> 
> So I guess the 1495 is *really* gone.
> 
> The good thing about this chip was that it contained
> more
> or less matched transistors for the gain cell, so
> offset and offset
> drift was under control. I.e. carrier suppression
> was good.
> Compander circuits will not make a good job for this
> carrier
> suppression, because it is not a wide band noise
> problem,
> but very narrow, so masking is poor.
> 
> And it had an input linearisation circuitry for the 
> carrier input, in order to have quite linear
> behaviour.
> The (still available) 1496 is designed for square
> wave
> carrier and has of course no input linearisation.
> So you have to use low carrier amplitude (noise)
> or accept excessive sidebands (distortion,
> intermodluation).
> Also the 1495 allowed to taylor the gain cell bias
> current.
> For good S/N you need a lot of current.
> Most other integrated multipliers do not allow for
> bias
> current change and are designed for low power
> consumption,
> so S/N of 80 dB will be the upper limit, and most
> devices
> will not even give that (AD633 for example).
> For some applications this is still too much noise.
> 
> I want low noise and linear behaviour (smooth
> sound).
> So next I try the RC4200 (?) and the 1496 with
> external DIY
> linearisation stage. If this doesn't work I'll go
> back to
> a complete discrete design, perhaps using a couple
> of
> japanese dual NPN, glue, expoxyd ... whatever it
> takes
> to cope with the offset problems...
> 
> 
> m.c.
> 
> 


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