Low-voltage differential voltage follower for WTA and fully differential applications

A low-voltage differential version of a high performance voltage follower is presented. The proposed circuit is very compact, and symmetric with respect to the input devices. Both differential input devices are enhanced by local shunt feedback, increasing the gain and, thus, reducing the output resistance for higher precision. The circuit has proved useful as a winner-take-all (WTA) circuit. It also features operation as a fully differential amplifier with low supply voltage requirements close to a transistor’s threshold voltage. Experimental results verifying the operation of the proposed structure are provided.