A Highly Linear Single-Balanced Resistive X-band MMIC Mixer in GaN HEMT Technology

In this paper a highly linear X-band MMIC mixer implemented in a 0.25μm GaN HEMT technology is presented. The mixer is based on a single-balanced resistive architecture using a pair of symmetrical 4×125μm GaN HEMTs. A novel minituarized half-wavelength hair-pin type of balun creates the balanced LO signal to be fed to the gates. A lumped-element diplexer network is used to separate the IF and RF signals at the drains. The fabricated MMIC mixer demonstrates a 6.9 dB conversion loss at 10 GHz with an LO power of +24.6 dBm and a bandwidth from 7.8−12.2GHz. Over the same bandwidth the single-tone second and third-order spurious responses are below -66 dBm and -98 dBm, respectively, at an RF input power level of -10 dBm. The experimental results furthermore show that the two-tone third-order input intercept point (IIP3) reaches ∼30 dBm at an applied LO power of +24.6dBm.