Design of Low-Voltage, Low-Power Operational Amplifier Cells

This text describes the theory and design of the circuit elements that are required to realize a low-voltage, low-power operational amplifier. These elements include constant-gm rail-to-rail input stages, class-AB rail-to-rail output stages and frequency compensation methods. Several examples of each of these circuit elements are investigated. Furthermore, the book illustrates several silicon realizations, giving their measurement results. The text focuses on compact low-voltage low-power operational amplifiers with good performance. Six simple high-performance class-AB amplifiers are realized using a very compact topology making them particularly suitable for use as VLSI library cells. All of the designs can use a supply voltage as low as 3V. One of the amplifier designs dissipates only 50 & micro; W with a unity gain frequency of 1.5 MHz. A second set of amplifiers run on a supply voltage slightly above 1V. The amplifiers combine a low power consumption with a gain of 120 dB. In addition, the design of three fully differential operational amplifiers is addressed.