A CMOS temperature-compensated current reference

A temperature-compensated current reference for CMOS integrated circuits based on a MOSFET as current-defining element, is described. To minimize the mass-production cost, it uses no external components nor trimming procedures. Comparison with classical current references with a resistor as a current-defining element shows a considerable improvement of the relative tolerance on the current. Theoretical expressions are presented and compared with experimental results from an integrated prototype. For devices from the same batch, the standard deviation is measured to be 2.5%, and the temperature dependence is 3% from 0 to 80 degrees C. From theoretical equations, the standard deviation of devices from different batches is expected to be about 15%.<>