This paper presents a multicarrier 60GHz transmitter for distance measurement (ranging) in an indoor wireless localization system, achieving mm-precision with high update rate. The architecture comprises a baseband subcarrier generator, an upconverter, and a power amplifier. There are three key innovations, all stemming from careful hardware-algorithm co-design: 1. efficient frequency planning of the 6GHz-wide band; 2. power-efficient multicarrier signal generation by means of digital frequency divisions exploiting the phase-based time-of-arrival ranging algorithm; and 3. PAPR reduction to enable efficient operation of the power amplifier. By implementing these key techniques, 0.7-2.7mm precision is achieved over 5m measured distance with 5.4µs symbol duration. During operation, the core digital subcarrier generator generates 16 non-equidistant subcarriers from a 3GHz input clock, while consuming an average power of 1.8mW out of 0.9V supply. The upconverter and the power amplifier altogether consume around 127mW. The total area of the transmitter is 1.1mm2 . The chip is fabricated in a 40nm general purpose CMOS process.P. Indirayanti, T. Ayhan, M. Verhelst, W. Dehaene, and P. Reynaert are with the MICAS Division, Departement of Electrical Engineering (ESAT), KU Leuven,