Biasing of the circuit with implementation of floating sources

Implementation of floating sources

The next step of biasing is to swap out the floating voltage sources for transistor implementations. The following figure shows the chosen implementation to create floating sources.

Biased circuit

After implementation, the full circuit is shown in the following figure. One other change is that the voltage on the source of the first transistor of the differential pair is adjusted for the lower common-mode voltage after the differential pair. This has no drastic influences on the performance of the amplifier

Conclusion on amplifier performance

The performance of the amplifier is still within specs after creating the floating sources. The AC analysis barely changes, the noise performance has enough headroom for the added transistors and resistors and the amplifier can still drive around $400 mV$. There is a little more weak nonlinearity, but it still is within specifications as seen in the following figure.