TABLE OF CONTENTS Basic MOS amplifiers are the main building blocks of a vast array of analog signal processing systems as well as other analog electronic circuits. The overall performance of a complex circuit strongly depends on the performances of its basic building blocks. In this chapter the main properties of these basic circuits will be investigated.
The basic structure of a common source amplifier is shown in Fig. 2.1(a). The gate of the NMOS transistor, M, is biased with a DC voltage source V GS, to conduct the appropriate DC (quiescent) current. A signal source ( v i) is connected in series with the bias voltage to control the drain current. The load resistor R D helps to convert the drain current variations into output voltage variations (output signal). Since the output of a MOS amplifier is usually connected to the gate of another MOS amplifier, the DC and low-frequency load coming from the subsequent stage is negligible [1] and the only load is R D. In Fig. 2.1(b), this DC load line with a slope equal to ( ?1/ R D) is drawn on the output curves of M. For a given value of the gate bias voltage (for example V GS1), the drain current is I D1, which corresponds to the intersection of the load line and the output curve corresponding to V GS1. This intersection point is called as the operating point or...
