A high-gain, low-power CMOS op amp using composite cascode stages

This work demonstrates that the composite cascode differential stage, operating in the subthreshold region, can form the basis of a high-gain (110 dB), low-power op amp (27.8 μW). The circuit can be fabricated without adding a compensation capacitance. Advantages of this architecture include high voltage gain, low harmonic distortion, low quiescent current and power, and small chip area. These advantages suggest that this design might be well-suited for low-power instrumentation applications requiring multiple amplifiers as often found in biomedical applications.