A high-performance, low-cost, leading edge discriminator has been designed with a timing performance comparable to state-of-the-art, commercially available discriminators. A timing error of 16 ps is achieved under ideal operating conditions. Under more realistic operating conditions the discriminator displays a timing error of 90 ps. It has an intrinsic double pulse resolution of 4 ns which is better than most commercial discriminators. A low-cost discriminator is an essential requirement of the GRAPES-3 experiment where a large number of discriminator channels are used.