This article explores the effect of using source follower buffers (SFB) at the output of source coupled logic (SCL) circuits. This technique can help to improve the power-delay product (PDP) in an SCL gate by a factor close to two. The proposed approach has been applied to improve the PDP in sub-threshold SCL circuits that have been developed for ultralow power applications. Designed in conventional digital 0.18um CMOS technology, the proposed SCL gate utilizing SFB at the output achieves a PDP of 0.5fJ/fF/gate while the gate draws 10nA from a 0.6V supply voltage.