03-05-2017 | | By Paul Whytock
In two separate design projects Gallium Nitride (GaN) technology has surpassed GaAs passive mixer designs relative to input third-order intercept point to local oscillator drive and has facilitated increased solar power inverter efficiencies.
Manufacturer of monolithic microwave integrated circuits (MMICs), Custom MMIC, has during the past 12 months had mixer experts investigating the use of GaN processes as the technical foundation for extremely linear RF mixers.
Recognising that the high linearity performance of GaN power amplifiers may be adaptable for various microwave components, the company’s engineers worked through various design iterations of GaN mixer technologies and typologies with a number of different foundry partners.
According to the company this eventually culminated in passive GaN mixer designs that surpass GaAs passive mixer designs in terms of the ratio of input third-order intercept point (IIP3) to local oscillator (LO) drive. From S-band to K-band (2 GHz to 19 GHz) these new passive GaN mixers are demonstrating IIP3 figures above 30 dBm, LO drive levels around 20 dBm and linear efficiencies above 10 dB.
Gallium Arsenide (GaAs) has for many years 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 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. IF=100 MHz USB.
GaN Power Boost
In a separate Gallium Nitride development, transistors from fabless power semiconductor company, GaN Systems, are being used by power inverter design engineers to increase power efficiency whilst simultaneously cutting inverter size and weight. GaN operational advantages means energy systems specialists SolPad have designed into its FlexGrid inverter GaN Systems’ 650V GaN transistors.
Concern over whether silicon or SiC solutions would provide the required inverter performance, SolPad selected GaN Systems transistors. The company says the 650 V GaN transistors delivered significant performance advantages. Gallium Nitride transistors also helped to provide system stability across a range of power levels.