A 20–40 GHz Harmonic Rejection Enhanced Frequency Doubler in 150 nm GaAs p-HEMT

This paper presents a broadband monolithic microwave integrated circuit (MMIC) frequency doubler within a 20-40GHz frequency operation range in a 0.15μm GaAs p-HEMT process. A broadband balun with a branch line compensation is employed in the frequency doubler to improve the suppression of the fundamental and odd harmonics signal. The branch line compensates for the phase mismatch of the broadband balun to excite more balanced differential signal, which effectively suppresses the unwanted fundamental and odd harmonic components; In addition, an integrated filtering technique with multiple zero-point control is introduced to the driver amplifier, enhancing the overall out-of-band harmonic suppression capability of the frequency doubler. The experimental results show that, with an input power of 0 to 1 dBm, the output power of the second harmonic of 16 to 17 dBm is achieved with the corresponding frequencies ranging from 20 to 40 GHz. The typical suppression of the fundamental signal and the third harmonic exceeds 38dBc, and the typical suppression of the fourth harmonic exceeds 30dBc. The power consumption is 100mA at +5V with chip are of 1.6mm*1.25mm.