Design and analysis of a two-stage CMOS op-amp using Silterra´s 0.13 μm technology

This paper presents the design and analysis of a high-gain, low-power, two-stage CMOS operational amplifier (op-amp) for a sigma-delta ADC. Op-amp topologies, such as folded cascade, telescopic and two-stage, are discussed in this paper. The theoretical and topological analyses of each design are highlighted in detail, including the tradeoff among various parameters such as gain, noise, output swings and power consumption. The designs have been simulated using 0.13 μm CMOS technology from Silterra (Malaysia) with Cadence EDA tools. From the simulation results, the two-stage amplifier gives better performance compared to other topologies, especially in terms of gain, output swing, slew rate and CMRR. The circuit is able to achieve 85.93 dB gain, a 1.1 V output swing, a 44.29 V/μs slew rate and a CMRR of 61 dB with a power supply voltage of 1.2 V.