[sdiy] Discrete SSM2040 & Spice

[Antti Huovilainen]

Hello

When doing Spice simulations of a discrete SSM2040 filter stage 
(http://www.uni-bonn.de/~uzs159/rs2040.htm), the output appears to have 
some 0.3V DC offset (even though the transistors are perfectly matched). 
I have traced this to the difference in the collector voltages of the 
differential pair (Early effect basically).

Is it really this huge in the real circuit or is my Spice faulty?
If Spice is right, what is the point of matching the differential pairs 
when Early effect alone causes such huge offset?

Antti

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