Four-quadrant multiplier using the floating-bulk technique for rail-to-rail input range and insensitivity to different input dc levels

Abstract

A four-quadrant analog multiplier with ultra-low supply voltage operation, rail-to-rail input swing and insensitive to different dc levels between the multiplied input signals is presented. It is based on the Floating-Bulk technique, in which the input signal is coupled to the bulk terminal of a PMOS transistor by means of an input capacitor. This allows rail-to-rail operation and eliminates the dc level of the input signals regardless of the offset between them, maintaining linearity. Moreover, it also eliminates the threshold-voltage requirement in the signal path of the input transistors, allowing very low voltage operation defined by a gate-source and a drain-source voltages. Experimental results in 0.5µm technology demonstrate rail-to-rail operation with a 1.1 V supply voltage even with different dc level voltages between the multiplied input signals. It offers a distortion of THD = 0.95 % for an input signal of 0.2Vpp at 100kHz.