For decades, gallium arsenide (GaAs) has been the process of choice for passive mixers fabricated on monolithic microwave integrated circuit (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 have generally been unachievable in GaAs. Custom MMIC has recently investigated the use of gallium nitride (GaN) to break through this linearity stalemate. Using GaN MMIC processes, Custom MMIC has achieved mixer IP3 levels of +40 dBm, with a very high linear efficiency of 10 to 15 dB.