Analog integrated circuit design using fixed-length devices

This work explores a simple method for implementing longer transistors: connecting devices in series, herein called the series-stack. The series-stack may be necessary for designers using fixed-length transistors, while requiring high gain and low noise performance. To test the feasibility of this architecture, a two-stage CMOS amplifier is designed using the TSMC 65nm process. Analysis of the results yield differences from 2% to 30% between the series-stack and traditional methods, depending on the metric. Yet, most discrepancies are expected, and the two implementations follow similar trends with respect to current density and length. The series-stack is deemed a suitable alternative to long transistor designs, especially when considering organizational advantages at the layout level.