The amplifier in this part is the same, in principle, as the basic common-source amplifiers of Figs. 2.4 and 5.1. However, now the actual resistor RD is replaced with a current-source load as shown in the circuit of Fig. 10.1. As noted in Unit 9, a benefit of replacing bias resistors with current sources is a reduced requirement for resistors in the circuit; the reference voltage associated with M3 can be used elsewhere in a typical circuit. Additionally, as will be shown, the gain of the common-source stage is substantially improved over that with actual bias resistor RD. The specific circuit of Fig. 10.1 is that for the project amplifier. The bias and gain of the amplifier are evaluated in the following.
3.17.5.68