Simple low-voltage weak inversion MOS 1/x circuit

A circuit with a transfer function I/sub out/=c/I/sub in/ (1/x circuit) with MOSFETs biased in weak inversion is presented. The circuit operates at a supply voltage that is a few hundred millivolts above one threshold voltage. The accuracy is +4%/-8% with respect to the desired transfer over a 6 pA to 2 nA input current range. >