A W-Band Power Efficient Frequency Doubler

A frequency doubler is reported in a hybrid Microwave Integrated Circuit (MIC) configuration using a Schottky diode based design at the W-band. Unwanted harmonic reuse scheme has been adopted for optimal use of the nonlinearity of the multiplying semiconductor device. Commercially available low cost device has been used in this simple balanced design and required results have been achieved. A comparison with prior art works indicates competitive performance. Output power is enhanced by reflecting the unwanted harmonics from the output side back towards the diode again, which mixes with the input fundamental frequency to effectively enhance the output power at the desired harmonic frequency. Thus, improvement in conversion loss is accomplished. A special technique using microstrip stubs has been adopted to provide proper RF grounding to the Schottky varactor diodes at the desired frequency. Measured result shows a minimum conversion loss of 19.8 dB over 89 to 99 GHz with 15 dBm of input power. Spurious rejection is in excess of 50 dBc. Measured output spectrum is highly stable with elevated spectral purity. Therefore, the proposed frequency multiplier is useful for Wband transceivers for wireless communication, imaging and other potential applications.