A floating-gate-based programmable CMOS reference

We describe a compact programmable CMOS reference, where the reference is determined by the charge difference between two floating-gate transistors, thereby making the reference insensitive to temperature and other environmental effects. Using floating-gate transistors adds programmability making a wide range of reference voltages possible with negligible long-term drift. A prototype circuit has been implemented in a 0.35-[mu]m CMOS process, and reference voltages ranging from 50 mV to 0.6 V have been achieved. We demonstrate a voltage reference programming accuracy of [+ or -] 4-40 [mu]V. Experimental results indicate a temperature sensitivity of approximately 53 [mu]V/[degrees]C for a nominal reference voltage of 0.4 V over a temperature range of -60[degrees]C-140[degrees]C. Index Terms--Current reference, floating-gate transistors, voltage reference.