A frequency doubler with high conversion gain and good fundamental suppression

A frequency doubler architecture with high conversion gain and high suppression of the input frequency is presented. The basic form operates at supply voltages down to 1.2 V and the simple topology allows for broad band operation. The new design was applied to a K/sub u/-band frequency doubler which drives the LO port of a single-balanced Gilbert mixer. Fabricated in an advanced SiGe-HBT technology with f/sub T/ = 80 GHz / f/sub max/ = 90 GHz, the compact design of LO buffer, LO doubler and mixer measures just 295 /spl mu/m /spl times/ 325 /spl mu/m (excluding pads). A conversion gain of +17 dB at an output frequency of 14 GHz has been achieved for the doubler (including buffers), while the mixer conversion gain is +8.4 dB.