Super-Gain-Boosted AB-AB Fully Differential Miller Op-Amp With 156dB Open-Loop Gain and 174MV/V MHZ pF/μW Figure of Merit in 130nm CMOS Technology

Abstract

A fully differential Miller op-amp with a composite input stage using resistive local commonmode feedback and regulated cascode transistors is presented here. High gain pseudo-differential auxiliary amplifiers are used to implement the regulated cascode transistors in order to boost the output impedance of the composite input stage and the open-loop gain of the op-amp. Both input and output stages operate in class AB mode. The proposed op-amp has been simulated in a 130nm commercial CMOS process technology. It operates from a 1.2V supply and has a close to rail-to-rail differential output swing. It has 156dB DC openloop gain and 63MHz gain-bandwidth product with a 30pF capacitive load. The op-amp has a DC open-loop gain figure of merit FOM AOLDC of 174 (MV/V) MHz pF/µW and large-signal figure of merit FOM LS of 3(V/µs) pF/µW.

A Review of Techniques to Enhance an Amplifier’s Performance Using Resistive Local Common Mode Feedback

“…This is in order to reduce the silicon area if resistors R >> ro1||ro2 are required to achieve maximum K enh values. Ultra high gain op-amps [39], Bulk driven and multistage operational amplifiers [29,35,45], rail-to-rail sample and hold circuits [18], buffers for high-density microelectrode arrays [24], LDOs [27], delta-sigma modulators [34], VGAs [36], gain and GB improved common mode feedback networks used in fully differential op-amps [30], etc. Other possible applications include the implementation of high frequency, high Q bandpass amplifiers using inductive common mode feedback (Figure 16c) where resistors are replaced by inductors and capacitors Ca, Cb by varactors C L to achieve tunable resonant frequencies ω res = 1/(LC L ) 1/2 in a multistage feedforward configuration similar to the one shown in Figure 13.…”

Analog CMOS Readout Channel for Time and Amplitude Measurements With Radiation Sensitivity Analysis for Gain-Boosting Amplifiers

“…To this end, several approaches have been introduced [13]- [16]. One of the most extended techniques is the regulated cascode, based on the use of an extra amplifier to achieve a local negative feedback loop that further enhances the output resistance of the circuit [17]. The implementation of this extra amplifier determines the performance of the complete op-amp in terms of power consumption, bandwidth, chip area, and supply voltage.…”