[sdiy] BJT Miller Integrator

[Magnus Danielson]

On 01/05/2012 07:59 PM, Justin Owen wrote:
> Can anyone point me to schematics/examples of a transistor miller integrator?
>
> I've got a model here: http://www.ecircuitcenter.com/Circuits_Audio_Amp/Miller_Integrator/Miller_Integrator.htm
>
> ...but I've also seen a 2x trasistor cascode(?) version.
>
> I'd be interested to see any other variations on this theme or, ideally - actual applications.

A modern variation of the scheme is the integrator cap sitting in SVF 
filters and also many saw or triangle oscillators.

An op-amp with a cap between the minus input and the output will achieve 
exactly the same thing as the Miller Integrator over a single 
transistor. The huge difference is the gain between input and output.

With this in mind you will find it in many places. Also, as Don pointed 
out, it is also used actively to reduce bandwidth of amps (so they do 
not act as oscillators). Again this variant is often seen in op-amps.

Cheers,
Magnus