[sdiy] OTA diodes

rsdio at audiobanshee.com rsdio at audiobanshee.com
Sun Jun 15 01:32:00 CEST 2014


Quick assessment is that the resistor, 3 diodes, and capacitor make up a simple voltage regulator. So long as the power supply is greater than 2 V, the node connected to the diodes and capacitor should stay at about 3 diode drops above ground. That would be between 1.8 V and maybe 2.1 V, depending upon the specific diodes. Not sure what range of current this can provide without further analysis.

I think Ian may have the purpose / improvement.

Brian


On Jun 14, 2014, at 12:01 PM, Justin Owen wrote:

> In Electronotes EN62 pg12 (one of the pages that is publicly available AFAIK...) there is a schematic of a basic OTA where the top current mirror hangs off a 680R resistor with 3 diodes to GND. I remember seeing this in another discrete OTA schem but never in the simplified schematics of the major production OTA's.
> 
> Recently I noticed that the simplified 2164 schematic uses a similar config - but in a different way (I think...).
> 
> What are these doing, what purpose do they serve, what are they improving? I'd be particularly interested in answers from an OTA POV.
> 
> Thanks!
> 
> - Justin




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