A CMOS Low-Voltage Super Follower Using Quasi-Floating Gate Techniques

摘要

A quasi-floating gate (QFG) "super-follower" is presented. The high resistance used by the QFG transistor is constructed by two diodes connected back-to-back, leading to a simple-, temperature-stable- and small-area solution. Expressions for the behavior of the follower are introduced and verified by circuit simulations in LTSPICE using 0.5 mu m CMOS process models, which show an improved performance of the proposed circuit with respect to the original super-follower. To prove the principle, a test cell was fabricated in the same 0.5 mu m CMOS technology and characterized. Measurement results show a gain-bandwidth product of 10 MHz and power consumption of 120 mu W with a 1.5 V single supply.