[sdiy] LM13700/LM13600-based filters

[Aaron Lanterman]

On Apr 26, 2010, at 12:13 PM, Harry Bissell wrote:

> The integrator is tied to the input of the darlington buffer, and will drift with the bias current it sees. If you use an inverting opamp intergrator, the same thing happens buut its a lot less severe
> than the internal buffers.

While we're on the topic, concerning VCAs and 1-pole OTA-C type sections built with 13700s, is there a consensus on which is better:

1) Drop the output of the ota through the resistor (VCA) or cap (VCF) to ground, and then buffer that with a noninverting op amp (wire from output to neg input)

2) Keep the output of the ota at virtual ground with an inverting op amp configuration, and send the current through a resistor (VCA) or cap (VCF) in the feedback loop of that op amp

- Aaron