Four-stage CMOS operational transconductance amplifier: Compensated via double differential blocks

Advancements in integrated circuits technology, force designers to adopt methods and approaches with posed limitations. Nowadays, multistage amplifiers are widely in demand due to high-gain performance while avoiding placing transistors vertically in contrast with cascode structures. In this work, a four-stage amplifier is investigated and frequency is compensated via a compensation network that includes two Miller capacitors at the outputs of differential blocks. So, using two Miller capacitors and sharing these capacitors common in four Miller loops, provide an opportunity to achieve acceptable frequency response regarding gain-bandwidth product and phase margin. The proposed amplifier is modeled symbolically and simulated with the HSPICE circuit simulator with the help of 0.18 mu m CMOS technology. According to the simulation results, the proposed approaches show superior performance compared with previously existing methods. Additionally, the sensitivity of the proposed amplifier against load and compensation capacitors expresses a stable and relatively fixed frequency response. Such a high gain amplifier with more than 180 dB as DC gain and 88 degrees phase margin, is in great demand for realizing modulators and data converters.

Automated summary

In this work, a four-stage amplifier is investigated and frequency is compensated via a compensation network that includes two Miller capacitors at the outputs of differential blocks. According to the simulation results, the proposed approaches show superior performance compared with previously existing methods. Additionally, the proposed amplifier demonstrates less sensitivity to load and compensation capacitors, resulting in a stable frequency response. Such a high gain amplifier is in great demand for realizing modulators and data converters.