This work presents an ultra energy efficient 60 GHz on-off keying (OOK) demodulator capable of data rates up to 19 Gbps. The demodulator consists of an envelope detector (ED), a baseband amplifier, and a Schmitt trigger (ST). A novel envelope detection technique based on asymmetric inverters together with a cross-coupled gain-boosting circuit enable high-speed and low-power operation. Fabricated in a 22 nm fully-depleted silicon-on-insulator (FD-SOI) technology, the demodulator consumes only 5.7 mW from a 0.4 V supply. Together with a measured maximum data rate of 19 Gbps at a bit-error rate less than 10 −12 , a high efficiency of 0.3 pJ/bit is achieved. To the authors’ best knowledge this is the highest reported energy efficiency for 60 GHz OOK demodulators, making the circuit ideal for short range wireless communications such as wireless body-area networks (WBANS).