A simple variable-width CMOS bump circuit

In this paper, I present a simple CMOS bump circuit whose transfer characteristic width is electronically adjustable via a single back-gate bias voltage. The proposed circuit comprises two asymmetric differential pairs whose transfer characteristics can be shifted left and right about the origin by adjusting this back-gate bias. One output current from each diff pair is fed into a current correlator circuit, which produces the bump current. The circuit can simultaneously produce a complementary antibump current by summing the other two diff pair currents. I describe the proposed circuit's operation, present a large-signal analysis for weak-inversion bias currents, and show measurements from a proof-of-principle prototype made from commercially available MOS transistor arrays.