Compact low-voltage self-calibrating digital floating-gate CMOS logic circuits

We present a new real time reconfigurable floating-gate CMOS linear threshold element that does not require either UV-programming or Fowler-Nordheim tunneling / hot electron injection. Instead an initial UV-erase is used, in combination with an automatic periodic matching of the effective threshold voltages for NMOS and PMOS driving transistors. We show how the circuit can be used to implement the INVERT, NAND2, NOR2, and CARRY' functions. The circuit output depends on the number of 1s in the binary input. The Boolean function can be changed in real time by using one or more of the inputs as control signals instead of inputs for information processing signals. The circuit is suitable for subthreshold operation. Preliminary measurements for floating-gate logic are included.