[sdiy] Operational Transconductance Amplifiers

[Antti Huovilainen]

On Tue, 9 Mar 2010, Andre Majorel wrote:

> "An OTA is basically a two quadrant multiplier. It multiplies an
> input voltage by a control current and produces a current as its
> output. The OTA's transfer function is that of a differential
> transistor pair, which is pretty convenient, although, a bit tough
> to analyze."

Or to put it in very basic maths:
Iout = Iabc * tanh(Vin / 2Vt)
Vt = ~26mV (kT/q)

No need to bother with gm or unexplained constants.

Antti

"No boom today. Boom tomorrow. There's always a boom tomorrow"
   -- Lt. Cmdr. Ivanova