[sdiy] MC1495 multiplier chip discontinued completely

[John L Marshall]

I have four 1595 Ceramic NOOS. Make an offer.

Take care,
John
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Pacific Northwest Synthesizer Meeting
August 9, 2003
www.sound-photo.com
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----- Original Message ----- 
From: "Czech Martin" <Martin.Czech at Micronas.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Thursday, April 24, 2003 6:27 AM
Subject: [sdiy] MC1495 multiplier chip discontinued completely


> 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.
> 
> 
>