Low-voltage CMOS op-amp with rail-to-rail input and output signal swing for continuous-time signal processing using multiple-input floating-gate transistors

A scheme for low-voltage CMOS op-amp operation with rail-to-rail input and output signal swing and constant g_m is presented. Single-ended and fully differential versions are discussed. The scheme is based on the use of multiple-input floating-gate transistors and allows direct implementation of linear weighted addition of continuous-time signals. Simulations are presented that verify the scheme operating with a 1.2-V single supply, 1.2-V input and output solving, 5-MHz op-amp gain-bandwidth product, and a 192-μW power dissipation with a 50-pF load and 300×300 μm² silicon area. These results are obtained for 0.85-V transistor threshold voltages. Experimental results are shown that verify the correct functionality of the proposed approach