This paper presents design issues of a wideband, low power implementation of a frequency doubler (FD) in a commercial 0.18 lm CMOS process. The FD consists of two identical unbalanced source-coupled pairs with different width-to-length (W/L) ratios, whose inputs are connected in parallel and its output is taken singleended. Amplitude and phase mismatch at the differential input are considered and it is shown that there is minimal effect on the output amplitude of the 2nd harmonic for a 5 dB difference in input amplitude and a 45°difference in phase. Under matched conditions, the implemented frequency doubler can be operated at a supply voltage as low as 1 V, which corresponded to a power consumption of less than 1 mW, has a 3 dB output bandwidth of 4 GHz and a conversion gain of 2.5 dB. At a supply voltage of 1.2 V, the frequency doubler consumed 1.32 mW, has a 3 dB output bandwidth of 3 GHz and a conversion gain of 5 dB. The phase niose degradation is 6 dB in both cases.