Allen W. Hanson

150 W GaN-on-Si RF power transistor

A large periphery high power AlGaN/GaN HFET grown on a silicon substrate has demonstrated over 150 W of CW RF output power along with excellent drain efficiency of 65%. When operated under WCDMA modulation and 28 Vdc drain supply voltage, these devices produced 20 W of RF output power with a corresponding drain efficiency of 27% while achieving an adjacent channel power ratio (ACPR) of -39 dBc. A 36 mm device was tested in a DPD linearizer under multi-carrier WCDMA modulation and achieved 20 dB of linearity improvement with 35% drain efficiency. Lastly, device reliability data is presented and shows extrapolated 20 year drift estimates of less than 1 dB for Psat. Index Terms - AlGaN/GaN HFETs, GaN high electron mobility transistor (HEMTs), linearity, reliability, RF power transistors.

A high efficiency broadband monolithic gallium nitride distributed power amplifier

A 50-ohm 100–2200MHz distributed power amplifier (DPA) MMIC has been developed using Nitronex’s proprietary GaN-on-Si NRF1 process. The DPA MMIC exhibits −10dB minimum input/output return loss, 39.4dBm average output power, and a power added efficiencies of 30 to 66% over the entire bandwidth.

Performance of AlGaN/GaN HFETs fabricated on 100 mm silicon substrates for wireless basestation applications

Third generation wireless communications standards such as W-CDMA place challenging requirements on microwave power transistors. To date, these challenges have been addressed with two primary technologies, Si LDMOS FETs and GaAs FETs. A new technology (AlGaN/GaN HFET) that shows the potential for addressing these strict system requirements is now becoming available. The growth and fabrication of GaN-based HFETs on a manufacturable 100 mm silicon platform are discussed. Results from 36 mm GaN HFETs are reported with particular attention to their ability to address the needs of the W-CDMA base transceiver station output power stage, demonstrating in excess of 15 W output power at W-CDMA operation with -39 dBc ACPR and 29% drain efficiency. Results of initial high-temperature operating life testing are presented, showing excellent device stability at a junction temperature of 200/spl deg/C, and predicting about 10% drift in DC parameters and less than 1 dB in output power over a 20-year life.

The Development of a High Power SP4T RF Switch in GaN HFET Technology

The development of a high power single-pole four throw (SP4T) hybrid switch using AlGaN/GaN heterostructure field effect transistors (HFETs) on Si substrate is reported for the first time for applications up to 1.5 GHz. The off-state capacitance of a single-gate GaN based HFET is 250 fF and the on-state resistance is 4.1 at a gate length of 0.7 m and a width of 1 mm. The hybrid SP4T switch with a size of 44 mm was implemented for system applications of three transmit paths and a receiver, of which each was configured with a series-shunt self-biased configuration. The switch has achieved an insertion loss of 1.4 dB with power handling of 43 dBm at the transmitter paths and an optimized isolation of better than 25 dB at the receiver path at 1.5 GHz. In addition, a high voltage switch driver using the GaN HFET technology was designed with an input control voltage of 0/4 V to provide an output voltage of 0/26 V. This development provides a baseline design for our next generation monolithic microwave integrated circuit switches in GaN technology.

A broadband low cost GaN-on-silicon MMIC amplifier

The design and performance of a 0.1 to 5 GHz medium power distributed amplifier is described. The circuit is realized using a low-cost GaN-on-silicon MMIC process featuring 0.5 mum gate length GaN HFETs on a 150 mum thick high resistivity silicon substrate. The circuit was designed using a non-linear FET model and standard passive component models. The first pass circuit demonstrates a saturated output power of 2 W and a maximum efficiency of greater than 30% at 1 GHz at a drain bias of 15 V, and a saturated output power of 3 W and maximum efficiency of 23% at 2.5 GHz with a drain bias of 28 V.

A Comparison of AlGaN/GaN HFETs on Si Substrates in Ceramic Air Cavity and Plastic Overmold Packages

AlGaN/GaN HFETs on Si substrates have been assembled in ceramic air cavity and plastic overmold packages. Thermal, DC, small and large signal RF and reliability characterization have been performed on both types of devices. Thermal characterization shows that the thermal resistance of the plastic overmolded parts is higher resulting in higher operating temperatures. The higher operating temperature causes parameters such as the peak CW power to be lower than that seen in the ceramic air cavity package. The advantage of the plastic packaging resides in its >10x lower package assembly cost.

High-Power and High-Voltage AlGaN/GaN HEMTs-on-Si

GaN-on-Silicon technology is a highly manufacturable, reliable, and cost effective AlGaN/GaN HEMT platform. Maximum RF performance (power and efficiency) can be achieved by addressing two main areas related to the silicon substrate: the RF loss to the silicon substrate and the thermal resistance of the device to the heat sink. In this paper, we will report on how the two areas can be addressed in a realistic environment to enable high power, high voltage operation. This device technology can be used to develop high power amplifiers that are significantly smaller, lighter, and operate over a broad bandwidth.

AlGaN/GaN HFETs on Si Substrates for WiMAX Applications

AlGaN/GaN HFETs on Si substrates are tested under OFDM modulations and show excellent performance from 3.3GHz to 3.8GHz. Performance on an 8mm device (NPT35010) in power small outline package (PSOP2) shows 1.5W output power, 11.2dB gain, 28.6% drain efficiency and 2% EVM at 3.5GHz. Large periphery 36mm devices were mounted in ceramic packages (NPT35050) and showed greater than 7W output power, > 11dB gain, 27.2% drain efficiency and 2% EVM at 3.5 GHz. Additionally data was taken across process from 23 devices and 5 process lots to demonstrate repeatability. Finally the same RF data was collected over flange temperature from -40degC to +85degC and demonstrated stable performance over temperature. These results demonstrate the potential for GaN-on-Si HEMTs for use in WiMAX applications