Power performance of AlGaN-GaN HEMTs grown on SiC by plasma-assisted MBE

We report AlGaN-GaN high electron mobility transistors (HEMTs) grown by molecular beam epitaxy (MBE) on SiC substrates with excellent microwave power and efficiency performance. The GaN buffers in these samples were doped with carbon to make them insulating. To reduce gate leakage, a thin silicon nitride film was deposited on the AlGaN surface by chemical vapor deposition. At 4 GHz, an output power density of 6.6 W/mm was obtained with 57% power-added efficiency (PAE) and a gain of 10 dB at a drain bias of 35 V. This is the highest PAE reported until now at 4 GHz in AlGaN-GaN HEMTs grown by MBE. At 10 GHz, we measured an output power density of 7.3 W/mm with a PAE of 36% and gain of 7.6 dB at 40-V drain bias.     

Ka波段5W GaAs PHMET功率MMIC

报道了一款采用0.15μm GaAs功率MMIC工艺研制的Ka波段功率放大器芯片。芯片采用四级放大拓扑结构,在29～32GHz频带范围内6V工作条件下线性增益25dB,线性增益平坦度小于±0.75dB;饱和输出功率大于5W,饱和效率大于20%,功率增益大于22dB;1dB压缩点输出功率大于36.5dBm,效率大于18%。     

X- and Ka-band power performance of AlGaN/GaN HEMTs grown by ammonia-MBE

A report is presented on the power performance of deep submicron AIGaN/GaN high electron mobility transistors grown by ammonia molecular beam epitaxy. At 10 GHz, 70% power-added-efficiency (PAE) and 3 W/mm power density were demonstrated at a drain bias of 20 V. At 30 GHz, 31% PAE and 6.5 W/mm power density were achieved at a drain bias of 40 V.     

High-power AlGaN/GaN HEMTs for Ka-band applications

We report on the fabrication and high-frequency characterization of AlGaN/GaN high-electron mobility transistors (HEMTs) grown by molecular beam epitaxy (MBE) and metal-organic chemical vapor deposition (MOCVD). In devices with a gate length of 160 nm, a record power density of 10.5 W/mm with 34% power added efficiency (PAE) has been measured at 40 GHz in MOCVD-grown HEMTs biased at V/sub DS/=30 V. Under similar bias conditions, more than 8.6 W/mm, with 32% PAE, were obtained on the MBE-grown sample. The dependence of output power, gain, and PAE on gate and drain voltages, and frequency have also been analyzed.     

A high-efficiency class-E GaN HEMT power amplifier at 1.9 GHz

A single stage class-E power amplifier in GaN high electron mobility transistor (HEMT) technology is reported. The circuit operates at 1.9 GHz. At 30-V drain bias, a power-added-efficiency (PAE) of 57% and a maximum output power of over 37dBm was achieved, corresponding to a power density of 5.25W/mm. At 40-V drain bias, an output power of 38.7dBm is achieved at 50% PAE corresponding to a power density of 7.4W/mm.     

Millimeter-wave low-noise and high-power metamorphic HEMTamplifiers and devices on GaAs substrates

This paper reports on state of-the-art HEMT devices and circuit results utilizing 32% and 60% indium content InGaAs channel metamorphic technology on GaAs substrates. The 60% In metamorphic HEMT (MHEMT) has achieved an excellent 0.61-dB minimum noise figure with 11.8 dB of associated gain at 26 GHz. Using this MHEMT technology, two and three-stage Ka-band low-noise amplifiers (LNAs) have demonstrated <1.4-dB noise figure with 16 dB of gain and <1.7 with 26 dB of gain, respectively. The 32% In MHEMT device has overcome the <3.5-V drain bias limitation of other MHEMT power devices, showing a power density of 650 mW/mm at 35 GHz, with V_ds=6 V     

Watt-level Ka- and Q-band MMIC power amplifiers operating at lowvoltages

Ka- and Q-band watt-level monolithic power amplifiers (PAs) operating at a low drain bias of 3.6 V are presented in this paper. Design considerations for low-voltage operation have been carefully studied, with an emphasis on the effect of device models. The deficiency of conventional table-based models for low-voltage operation is identified. A new nonlinear device model, which combines the advantages of conventional analytical models and table-based models, has been developed to circumvent the numerical problems and, thus, to predict optimum load impedance accurately. The model was verified with load-pull measurements at 39 GHz. To implement a low-voltage 1-W monolithic-microwave integrated-circuit amplifier, careful circuit design has been performed using this model. A Q-band two-stage amplifier showed 1-W output power with a high power gain of 15 dB at 3.6-V drain bias. The peak power-added efficiency (PAE) was 28.5% and 1-dB compression power (P_{1 dB}) was 29.7 dBm. A Ka-band two-stage amplifier showed a P_{1 dB} of 30 dBm with 24.5-dB associated gain and 32.5% PAE. Under very low dc power conditions (P_dc<2 W, V_ds=3.4 V), the amplifiers showed 29-dBm output power and PAE close to 36%, demonstrating ultimate low-power operation capability. To the best of our knowledge, this is the first demonstration of watt-level PA's under 3.6-V operation at 26 and 40 GHz. Compared with the published data, this work also represents state-of-the-art performance in terms of power gain, efficiency, and chip size     

High-power microwave 0.25-μm gate doped-channel GaN/AlGaNheterostructure field effect transistor

We report on the high-power performance of the 0.25-μm gate Doped-Channel GaN/AlGaN Heterostructure Field Effect Transistors (DC-HFETs). At a drain bias voltage of 18 V and drain bias current of 46 mA, these 100-μm wide devices exhibit high gain at 8.4 GHz with a power density reaching 1.73 W/mm. The devices also display high gain at moderate power over a wide range of frequencies. This high gain at high frequency is a result of an optimal doping level in the AlGaN layer that gives rise to a high sheet charge density while maintaining a high-channel electron mobility. These results demonstrate the excellent microwave power capability of the GaN/AlGaN based heterostructure field effect transistors     

60-GHz high power performance In/sub 0.35/Al/sub 0.65/As-In/sub 0-35/Ga/sub 0.65/As metamorphic HEMTs on GaAs

We report on a double-pulse doped, double recess In/sub 0.35/Al/sub 0.65/As-In/sub 0.35/Ga/sub 0.65/As metamorphic high electron mobility transistor (MHEMT) on GaAs substrate. This 0.15-/spl mu/m gate MHEMT exhibits excellent de characteristics, high current density of 750 mA/mm, extrinsic transconductance of 700 mS/mm. The on and off state breakdown are respectively of 5 and 13 V and defined It gate current density of 1 mA/mm. Power measurements at 60 GHz were performed on these devices. Biased between 2 and 5 V, they demonstrated a maximum output power of 390 mW/mm at 3.1 V of drain voltage with 2.8 dB power gain and a power added efficiency (PAE) of 18%. The output power at 1 dB gain compression is still of 300 mW/mm. Moreover, the linear power gain is of 5.2 dB. This is to our knowledge the best output power density of any MHEMT reported at this frequency.     

The effect of surface passivation on the microwave characteristicsof undoped AlGaN/GaN HEMTs

Surface passivation of undoped AlGaN/CaN HEMT's reduces or eliminates the surface effects responsible for limiting both the RF current and breakdown voltages of the devices. Power measurements on a 2×125×0.5 μm AlGaN/GaN sapphire based HEMT demonstrate an increase in 4 GHz saturated output power from 1.0 W/mm [36% peak power-added efficiency (PAE)] to 2.0 W/mm (46% peak PAE) with 15 V applied to the drain in each case. Breakdown measurement data show a 25% average increase in breakdown voltage for 0.5 μm gate length HEMT's on the same wafer. Finally, 4 GHz power sweep data for a 2×75×0.4 μm AlGaN/GaN HEMT on sapphire processed using the Si₃N₄ passivation layer produced 4.0 W/mm saturated output power at 41% PAE (25 V drain bias). This result represents the highest reported microwave power density for undoped sapphire substrated AlGaN/GaN HEMT's     

High performance 0.14 /spl mu/m gate-length AlGaN/GaN power HEMTs on SiC

High electron mobility transistors (HEMTs) were fabricated from AlGaN/GaN on semi-insulating SiC substrates with excellent performance and high yield. The devices had 0.14 /spl mu/m T-gates with a total width of 300 /spl mu/m. Extrinsic, unpassivated peak performance values for these HEMTs include transconductance of 338 mS/mm, maximum drain current of 1481 mA/mm, unity current gain cutoff frequency of 91 GHz, and maximum frequency of oscillation of 122 GHz. Saturated CW power measurements of these devices at 10 GHz result in 4.6 W/mm with PAE at 46% when optimized for power and 3.0 W/mm with PAE at 65% when optimized for efficiency.     

High performance fully selective double recess InAlAs/InGaAs/InPHEMTs

InP HEMTs with a double recess 0.12 μm gate have been developed. The material structure was designed to be fully selective etched at both recess steps for improved uniformity and yield across the whole wafer. Devices demonstrated DC characteristics of extrinsic transconductances of 1000 mS/mm, maximum current density of 800 mA/mm and gate-drain reverse breakdown voltages of -7.8 V. Power measurements were performed at both 20 GHz and 60 GHz. At 20 GHz, the 6×75 μm devices yielded 65% maximum power added efficiency (PAE) with associated gain of 13.5 dB and output power of 185 mW/mm. When tuned for maximum output power it gave an output power density of 670 mW/mm with 15.6 dB gain and 49% PAE. At 60 GHz, maximum PAE of 30% has been measured with associated output power density of 290 mW/mm and gain of 7.4 dB. This represents the best power performance reported for InP-based double recess HEMT's     

八胞合成X波段140W AlGaN/GaNHEMT的研究与应用

主要研究第三代半导体AlGaN/GaN功率管内匹配问题.采用8个2.5 mm GaN功率芯片设计、合成以及内匹配电路的测试,在漏极电压40 V,脉冲占空比10％,脉宽100μs的条件下进行功率匹配,实现了GaN功率HEMT在X波段8 GHz 140 W功率输出的内匹配电路,并使整个电路的输入、输出电路阻抗提升至50 Ω...     

14W X波段AlGaN/GaN HEMT功率MMIC

报道了研制的SiC衬底AIGaN/GaN HEMT微带结构微波功率MMIC,芯片工艺采用凹槽栅场板结构提高AlGaN/GaNHEMTs的微波功率特性.S参数测试结果表明AlGaN/GaN HEMTs的频率特性随器件的工作电压变化显著.研制的该2级功率MMIC在9～11GHz带内30V工作,输出功率大于10W,功率增益大于12dB,带内峰值输出功率达到14.7W,功率增益为13.7dB,功率附加效率为23%,该芯片尺寸仅为2.0mm×1.1mm.与已发表的X波段AlGaN/GaN HEMT功率MMIC研制结果相比,本项工作在单位毫米栅宽输出功率和芯片单位面积输出功率方面具有优势.     

Millimeter-wave high-power 0.25-/spl mu/m gate-length AlGaN/GaN HEMTs on SiC substrates

Reports on the CW power performance at 20 and 30 GHz of 0.25 /spl mu/m /spl times/ 100 /spl mu/m AlGaN/GaN high electron mobility transistors (HEMTs) grown by MOCVD on semi-insulating SiC substrates. The devices exhibited current density of 1300 mA/mm, peak dc extrinsic transconductance of 275 mS/mm, unity current gain cutoff (f/sub T/) of 65 GHz, and maximum frequency of oscillation (f/sub max/) of 110 GHz. Saturated output power at 20 GHz was 6.4 W/mm with 16% power added efficiency (PAE), and output power at 1-dB compression at 30 GHz was 4.0 W/mm with 20% PAE. This is the highest power reported for 0.25-/spl mu/m gate-length devices at 20 GHz, and the 30 GHz results represent the highest frequency power data published to date on GaN-based devices.     

Highly efficient double-doped heterojunction FET's forbattery-operated portable power applications

Microwave power performance of double-doped AlGaAs-InGaAs-AlGaAs heterojunction field-effect transistors (HJFET's) operated at a drain bias of 3 V is described. The fabricated 1.0 μm gate-length HJFET exhibited a maximum drain current of 500 mA/mm, a transconductance of 300 mS/mm, and a gate-to-drain breakdown voltage of 10 V. Power performance for a 14 mm gate periphery device demonstrated a maximum output power of 1.7 W with a 66% power-added efficiency (PAE) at 900 MHz. When the device was tuned for a maximum PAE, it delivered a 71% PAE with an output power of 1.2 W. The results indicate that the developed HJFET has great potential for 3 V battery-operated portable power applications     

Metamorphic InAlAs/InGaAs enhancement mode HEMTs on GaAs substrates

In_0.5Al_0.5As/In_0.5Ga_0.5 As HEMTs have been grown metamorphically on GaAs substrates oriented 6° off (100) toward (111)A using a graded InAlAs buffer. The devices are enhancement mode and show good dc and RF performance. The 0.6-μm gate length devices have saturation currents of 262 mA/mm at a gate bias of 0.7 V and a peak transconductance of 647 mS/mm. The 0.6 μm×3 mm devices tested on-wafer have output powers up to 30 mW/mm and 46% power-added-efficiency (PAE) at 1 V drain bias and 850 MHz. When biased and matched for best efficiency performance, this same device has up to 68% PAE at V_d=1 V     

9.4-W/mm power density AlGaN-GaN HEMTs on free-standing GaN substrates

High power microwave AlGaN-GaN high electron-mobility transistors (HEMTs) on free-standing GaN substrates are demonstrated for the first time. Measured gate leakage was -2.2 /spl mu/A/mm at -20 V and -10 /spl mu/A/mm at -45 V gate bias. When operated at a drain bias of 50 V, devices showed a record continuous-wave output power density of 9.4 W/mm at 10 GHz with an associated power-added efficiency of 40%. Long-term stability of device RF operation was also examined. Under room conditions, devices driven at 25 V and 3-dB gain compression remained stable in 200 h, degrading only by 0.18 dB in output power. Such results illustrate the potential of GaN substrate technology in supporting reliable, high performance AlGaN-GaN HEMTs for microwave power applications.     

Power Stability of AlGaN/GaN HFETs at 20 W/mm in the Pinched-Off Operation Mode

High power-added efficiency (PAE) (ap74%) and rf-power (20 W/mm) operation of Schottky and insulated-gate AlGaN/GaN heterostructure field-effect transistors (HFETs) is reported at 2 GHz. In the pinched-off mode of operation, the PAE increases from a value of 55% to 74% when the drain bias is changed from 35 to 60 V. While both the Schottky and the insulated HFETs show high powers and PAE values, only the insulated-gate devices are stable at 20-W/mm output powers during a 60-h continuous wave rf-stress test. Their power drop of less than 0.1 dB is much smaller than the 0.8-dB drop for identical geometry Schottky-gate HFETs. The superior stability of the insulated-gate HFETs is attributed to the low forward gate currents     

Power Performance of AlGaN/GaN HEMTs Grown on SiC by Ammonia-MBE at 4 and 10 GHz

In this letter, we report on the microwave power and efficiency performance of AlGaN/GaN high-electron mobility transistors (HEMTs) grown by ammonia molecular beam epitaxy (ammonia-MBE) on SiC substrates. At 4 GHz, an output power density of 11.1 W/mm with an associated power-added efficiency (PAE) of 63% was measured at V _ds = 48 V on passivated devices. At 10 GHz, an output power density of 11.2 W/mm with a PAE of 58% was achieved for V _ds = 48 V. These results are the highest reported power performance for AlGaN/GaN HEMTs grown by ammonia-MBE and the first reported for ammonia-MBE on SiC substrates.