I have the following differential pair circuit that is designed to have a diff gain of 4 V/V and a power consumption of 1mW. The transistor should be biased to have a Veff=0.3V and should have a length of 0.25um. With uCox = 270 and Vt=0.45V. I should determine W in the transistors and the values of RD and Ibias. Do you have any idea of how can I find these parameters? I have some equations but I got to a point that doesn't make sense. Where should I account on the consumption power?

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  • \$\begingroup\$ The circuit is not included. \$\endgroup\$
    – Daniel
    Oct 20, 2015 at 1:03
  • \$\begingroup\$ No schematic, a diffpair by itself cannot have a voltage gain as it has current outputs. What is the load of the diffpair ? What is Veff ? Assume the transistors are in saturation mode and use the appropriate formula. \$\endgroup\$ Oct 20, 2015 at 7:51
  • \$\begingroup\$ Veff in this text book is Vov = Vgs-Vt \$\endgroup\$ Oct 20, 2015 at 14:17

1 Answer 1


Well, it seems it was easier than thought. I was stacked in a point. If I have the total power consumption (1mW) and the source voltage (1,8V) I can get the bias current and work with it.


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