A Ka-band broadband frequency doubler in a 0.18 μm SiGe BiCMOS technology is presented in this paper. The frequency doubler employs a configuration of a common-base (CB)/common-emitter (CE) pair to enhance the second harmonic efficiently. This frequency doubler features a conversion gain of higher than ™7 dB with an input power of 5 dBm between 26 and 40 GHz. The maximum output 1-dB compression point (P 1dB) is 4.3 dBm and the output saturation power (P sat) is higher than 5 dBm at 31 GHz. The overall chip size is 0.85×0.66 mm 2. To the best of the author's knowledge, this work demonstrates the first SiGe-based frequency doubler using CB-CE configuration with good output power and good figure-of-merit (FOM) covering the entire Ka band.