A broadband millimetre-wave differential pHEMT frequency doubler MMIC

This paper presents the design and performance of a broadband millimetre-wave frequency doubler MMIC using active 0.15-μm GaAs pHEMT and operating at output frequencies from 10 to 50GHz. Thanks to a differential pHEMT structure and distributed amplifier, the MMIC doubler exhibits more than 10dB conversion gain from 15 to 50GHz with more than 18-dBm of saturated output power. The fundamental rejection is typically -25dBc up to 40GHz and better than -15dBc to 50GHz. The chip size is 2.7mm² and nominal DC power consumption is 1250mW, although 6-dB broadband conversion gain is obtained with as little as 250mW of DC power. To the authors´ knowledge, these results represent the largest bandwidth and the highest gain-bandwidth product reported to date for any solid-state frequency doubler.