A Digitally Assisted Telescopic Amplifier With Improved ICMR and Programmable Unity Gain Frequency

Abstract: Telescopic amplifiers are often preferred for their large DC gain, low power dissipation and low flicker noise. On the other side, they suffer from serious problems like poor input common mode range and output swing. In this work, a simple technique to improve the input common mode range of telescopic structure is presented. To achieve this, two telescopic amplifiers using complementary differential pairs are utilized. The proposed design incorporates a digital switching technique which enables to maintain a flat response throughout the extended input common mode range. It also provides a facility to elevate the performance of the circuit over a predefined range of input common mode level, at the cost of extra power. The entire design is verified using UMC 180 nm CMOS technology and the simulation results are presented.