Broad bandwidth transformer coupled differential amplifiers for high dynamic range

Broad bandwidth amplifiers are typically limited in their spurious free dynamic range by second-order products. We have demonstrated more than 30 dB reduction in second-order products for amplifiers with 1-2 octaves of bandwidth utilizing a novel circuit approach. Improved planar baluns (180/spl deg/ transformers) are combined with differential amplifiers fabricated from 0.25-/spl mu/m GaAs pseudomorphic high electron mobility transistors to implement 4-16-GHz and 3-6-GHz small-signal amplifiers. Measured values of OIP2 exceed 60 dBm with a 1-dB compression level of approximately 5 dBm. These unprecedented levels enable miniaturized, low-power front ends for broad bandwidth microwave systems.