Passive GaN Mixers Reach New Benchmark Of Linearity

Ratio of input third-order intercept point to applied LO drive surpasses GaAs designs

Custom MMIC has announced a new technical brief illuminating its progress with reaching high limits of linearity with passive MMIC mixers using GaN technology.

For decades, GaAs has been the process of choice for passive mixers fabricated on MMIC technologies. However, in terms of linearity, GaAs mixers tend to have input third-order intercept (IP3) points that reach +20 to +24 dBm, which is typically only 3 to 8 dB above the applied LO drive. This level of ‘linear efficiency’, which is newly defined as the difference between IP3 and LO drive level, is one reason higher IP3 has generally been unachievable in GaAs.

Over the past year, mixer experts at Custom MMIC have been exploring the use of GaN processes as the basis for extremely linear RF mixers to break through this linearity ‘stalemate’.

Deducing that the high linearity performance of GaN power amplifiers may cross-over to other critical microwave components, Custom MMIC engineers have gone through several iterations of GaN mixer technologies and typologies with several of their key foundry partners.

Ultimately, the fruits of their efforts have led to passive GaN mixer designs that surpass all GaAs passive mixer designs in terms of the ratio of input third-order intercept point (IIP3) to local oscillator (LO) drive – a figure-of-merit Custom MMIC is coining as Linear Efficiency. From S-band to K-band (2 GHz to 19 GHz) these new passive GaN mixers are demonstrating IIP3 figures well above 30dBm, LO drive levels around 20 dBm, and linear efficiencies above 10dB.