20-40 GHz dual-gate frequency doubler using 0.5 μm GaAs pHEMT technology

A Ka-band dual-gate frequency doubler using 0.5 mu m GaAs enhancement-mode pHEMT process is presented. The cascode circuit is equalised to the dual-gate frequency doubler and the relationship between bias and output matching is discussed to obtain the maximum output power and conversion efficiency. Since a pinch-off gate-to-source bias is driven at the input gate node, the frequency doubler consumes little DC power when injecting a low-power fundamental signal. Based on the analysis, the designed dual-gate doubler has a 3 dB bandwidth of 5.6 GHz, from 36 to 41.6 GHz. The fundamental suppressions are better than 15 dB. The measured maximum conversion gain is -0.9 dB at an injected power of 7 dBm. A high saturation output power is 7 dBm with a conversion efficiency of 14.3%. The measured results confirm the validity of the proposed analysis method.