PROBLEM 014 · Beginner · The PMOS common-source stage
Mirror Universe
PMOS common-source amplifier
The problem
Build a common-source amplifier with a PMOS: its source on VDD, its gate driven by an Input source named “in”, and a resistor from its drain to ground as the load. The output is the drain, “out”.
Everything is mirrored from the NMOS stage. The gate voltage must be below VDD by more than |Vth| for the transistor to conduct, the current flows from the supply down through the load, and a rising input makes the output fall.
The test bench
- Supply: VDD = 1.8 V.
- The test bench hangs a 200 fF load capacitor from “out” to ground and applies the AC stimulus to “in”.
Numbers to hit
- Gain at least 14 dB
- Bandwidth (−3 dB) at least 25 MHz
- Output DC level between 0.5 V and 1.1 V
- Power at most 150 µW
- Every transistor in saturation
Design it yourself
Draw the circuit on a schematic canvas, size every transistor, and see it simulated in your browser with ngspice and the SkyWater SKY130 models. Every transistor lights up green, gold or red by operating region as you move the sliders.
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