Mpc508

[Raka]

Does anyone have a clue on what is the expected THD figure of this device?

[anatech]

Hi Raka,
In my experience, it depends on the source impedance and input impedance. Basically you want the current through the device to be small. I have never seen anyone spec distortion in these devices because there are too many variables. Possibly they did many years ago.

I've never been satisfied with IC switching. Perhaps this part will be better. All you can do is try it and play with impedances. Not unless the spice model is accurate, then you can play at no real cost.

-Chris

[jaycee]

This is probably not exactly helpful, but when I've seen mux IC's used in audio equipment, it's always been the Analog Devices parts. They do improved versions of the standard DG508/9 series.

[Raka]

Thanks. My concern is the thd figure because I'm designing a jig to control the signals for a pc measurement system and a mux would simplify very much the scheme. I need low thd because I intend to measure also line circuits and power amps.

The impedance thing is easy to control, as two buffers would do, with low thd.

I'll search on Analog, I really want to use a mux instead of relays in my circuit.

[anatech]

Hi Raka,

I really want to use a mux instead of relays in my circuit.

I understand. I fear you will be stuck using relays. They are the only true low distortion connection. You may also have to watch digital feed through with a mux chip and any other high frequency signal. PSRR in practice may bear watching also.

Good luck! Please let us know if you find a device worth using.

-Chris

[Raka]

The AD8174 might be good, but I haven't found a place to buy it.
Maxim has also the MAX4312 part, which also looks fine, but again, no place for buying it at the moment.