current mirror

Hi, I'm currently struggling to solve the biasing of this circuit without ORCAD (so as an exercise). The parameters given are referred to all thre PMOS. A previous polarization with LAMBDA=0 gives Vout=1.25V. I'll call the Early resistance r0 . I've had no problems biasing the mosfet M3...

I found this circuit below from a research paper and been trying to simulate it without success. The circuit is about measuring capacitance values of the Femto range. Please give your suggestion so that I will be able to measure the capacitance of a very small value.

The attached schematic is taken from the Raspberry Pi drawing. I am trying to understand how it works and I am pretty much stuck with it. I guess the purpose of the resettable PTC fuse and the TVS diode is clear, being as overvoltage protection. It looks quite obvious that the transistors are...