DCCII based frequency compensation method for three stage amplifiers

Abstract

A new frequency compensation scheme using a second generation differential current conveyor (DCCII) for three-stage amplifiers is proposed. By adding a DCCII as a feedback path from output of the second and the third stage to the output of the first stage, feed-forward path and the right-half plane zero will be removed subsequently, which significantly improves phase margin and gain-bandwidth product. Calculations are derived for two states. First state, a DCCII and two miller capacitors form the feedback paths and in the second state, two nulling resistors will be set series with miller capacitors. Analyses show that in both states, stability can be perfectly ensured.To demonstrate advantages of this technique over the traditional RNMC architecture, a three-stage amplifier is designed and simulated employing the proposed technique in a standard 0.18μm CMOS process. Simulation results show that, with the same load capacitance, the new amplifier achieved 85° and 9.63MHz as phase margin and gain-bandwidth product, respectively. The proposed amplifier dissipates only 0.31mW of power with a 1.8V supply.