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-mum CMOS process, and reference voltages ranging from 50 mV to 0.6 V have been achieved. We demonstrate a voltage reference programming accuracy of plusmn40 muV . Experimental results indicate a temperature sensitivity of approximately 53 muV/degC for a nominal reference voltage of 0.4 V over a temperature range of -60degC-140degC.