For a block of memory cells interconnected by single-ended bit lines, a sense amplifier receives the input from a single-ended bit line to determine the logic state of a selected memory cell connected to the single-ended bit line. The sense amplifier also receives a reference voltage generated from a base-emitter voltage of a emitter follower bipolar transistor. The base-emitter voltage is controllably divided by a voltage divider network with selectable resistive elements to tune the reference voltage.