A current-controlled linear MOS earthed resistor that requires only three transistors is realised by means of a new linearisation technique. A nonlinearity within ±1.5% full scale in the 0–4V voltage range for a 5V supply is experimentally achieved with discrete MOS devices. However, much higher linearity can be expected if we choose the ratio of two transistor sizes exactly, according to the derivation in the paper. A floating resistor, derived from the earthed one, is also presented.