An integrated channel noise-based true random number generator

The circuit described retrieves true random numbers from CMOS channel noise, suitable for Smart Card applications. The new concept uses MOS transistors in subthreshold and linear region, and applies continuous time offset cancellation. By this technique a high, well defined gain and small area is achieved simultaneously. A two-stage amplifier architecture ensures low sensitivity to supply and substrate noise. The presented solution is simple and does not require tuning. It was implemented in a 0.18 mum SMIC process, consuming only 25 muW with a 1.8 V supply. Good entropy values can be obtained with sampling frequencies up to 5 MHz.