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Opamp 1

A simple discrete opamp

by Merritt Miller

not rated -

This is a little Opamp that I created for fun. The phase margin is a little thin but besides that its a pretty functional little circuit.

Vsupply =+/- 20V
Avol= 86db
Ft= 100MHz
Phase Margin=26 degrees
CMRR= 143db @1k
PSRR= 104db @1k
1/f corner: ~25Hz
In-band (25Hz-100MHz) input referred noise: 40uV

Vsupply =+/- 5V
Avol= 83db
Ft= 86.5MHz
Phase Margin=30 degrees

Components:
PNP : 2N3906 (x8)
NPN: 2N3904 (x19)

5 ohm resistors (x4) 1% or better
3 ohm resistor - controls bias current accuracy preferable not necessary
.7Mohm resistor - 10% is good enough (its for booting)

33pf capacitor (rated for the full supply voltage)

Schematic:

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