GaAs microwave power FET

A design consideration for an X-band GaAs power FET, features of the fabrication process, and electrical characteristics of the FET are described. Interdigitated 53 source and 52 drain electrodes and an overlaid gate electrode for connecting 104 Schottky gates in parallel have been introduced to achieve a 1.5-µm-long and 5200-µm-wide gate FET. A sheet grounding technique has been developed in order to minimize the common source lead inductance (L8= 50 pH). The resulting devices can produce 0.7-W and 1.6-W saturation output power at 10 GHz and 8 GHz, respectively. At 6 GHz, a linear gain of 7 dB, an output power of 0.85 W at 1-dB gain compression and 30-percent power added efficiency can be achieved. The intercept point for third-order intermodulation products is 37.5 dBm at 6.2 GHz.     

DC and RF Characteristics of 0.15 pm Power Metamorphic HEMTs

DC and RF characteristics of 0.15 °m GaAs power metamorphic high electron mobility transistors (MHEMT) have been investigated. The 0.15 °m ° 100 °m MHEMT device shows a drain saturation current of 480 mA/mm, an extrinsic transconductance of 830 mS/mm, and a threshold voltage of ‐0.65 V. Uniformities of the threshold voltage and the maximum extrinsic transconductance across a 4‐inch wafer were 8.3% and 5.1%, respectively. The obtained cut‐off frequency and maximum frequency of oscillation are 141 GHz and 243 GHz, respectively. The 8 ° 50 °m MHEMT device shows 33.2% power‐added efficiency, an 18.1 dB power gain, and a 28.2 mW output power. A very low minimum noise figure of 0.79 dB and an associated gain of 10.56 dB at 26 GHz are obtained for the power MHEMT with an indium content of 53% in the InGaAs channel. This excellent noise characteristic is attributed to the drastic reduction of gate resistance by the T‐shaped gate with a wide head and improved device performance. This power MHEMT technology can be used toward 77 GHz band applications.     

High-efficiency GaAs power MESFETs prepared by ion implantation

GaAs power MESFETs have been fabricated using ion implantation to form channel layers. A 1 ?m gate length by 2400 ?m gate width device has demonstrated an output power of 1.63 W with 6.9 dB associated gain, 35% power-added efficiency and 9.7 dB linear gain at 10 GHz. The transconductance of this device is 280 mS, which corresponds to 117 mS/mm. This result demonstrates that excellent GaAs power MESFETs can be made by ion implantation, and is comparable to average results demonstrated by devices made by AsCl3 vapour phase epitaxy.     

High-power GaAs FET's prepared by ion implantation

High-power GaAs FET's have been developed by using ion implantation to form channel layers and n⁺ohmic contact regions. The burn-out characteristics have been improved by introducing n⁺regions with high surface carrier concentration. The source-drain burnout voltage has been found to be more than 40 V. The distributions of saturated source-drain current (Idss) and RF output power of the devices have been found much more uniform than those of power GaAs FET's prepared by metalorganic chemical vapor deposition (MOCVD). Multichip operation of the FET's has demonstrated an excellent power combining efficiency due to the good uniformity among the chips. The two-chip device (total gate width WG= 14.4 mm) has delivered 5 W at 10 GHz with 4-dB gain and 23-percent power added efficiency (ηadd). The four-chip device (WG= 28.8 mm) has given 10 W at 8 GHz (gain = 4.5 dB, ηadd= 23 percent). The four-chip device (WG= 48 mm) has developed 15 W at 5 GHz (gain = 8 dB, ηadd= 30 percent).     

A low-distortion K-band GaAs power FET

A K-band low-distortion GaAs power MESFET was developed by incorporating a pulse-type channel doping profile using molecular-beam-epitaxial technology and a novel 0.3-μm T-shaped gate. The low-distortion FETs offer about 10 to 15 dBc improvement in second-harmonic distortion compared to devices fabricated on a uniformity doped active layer. Significantly larger power load-pull contours are obtained with the low-distortion devices, indicating the improved linearity of these devices. In an 8-20-GHz single-stage broad-band amplifier, up to 10 dBc improvement in harmonic performance was achieved using the low-distortion device. This low-distortion device exhibits very linear transconductance as a function of the gate bias. A typical 750-μm-gate-width device is capable of 26 dBm of output power with 6 dB of gain, and power-added efficiency in excess of 35% when measured at 18 GHz. At 25 GHz, the device is capable of 24 dBm of output power with 5 dB associated gain     

Theoretical characterization and high-speed performance evaluation of GaAs IGFET's

Fundamental characterization of GaAs IGFET's is carried out utilizing two-dimensional numerical analysis, and high-speed operation performances are evaluated. Two-dimensional analysis shows that the operational mechanism of GaAs IGFET's is very similar to that of MESFET's, i.e., channel depletion-type operation due to control of the gate depletion layer. But normally-off-type current-voltage characteristics can be easily realized because of positive VFBfor GaAs dioxide films. Electrical characteristics are strongly dependent on the oxide film. Although the transconductance gmdeteriorates compared to MESFET's due to the potential drop through the oxide layer, the deterioration in gmis found to be small for oxide films with large dielectric constant εOX. Furthermore, it is clarified that cutoff frequency fTfor IGFET's is greater than for MESFET's because the input capacitance Cgsin depletion-type device operation is found to be much smaller than for MESFET's. In additional, a high-voltage swing is applicable in device operation because of the IG structure, and higher gm, is achieved by supplying high gate biases. These features give GaAs IGFET's wide application fields as high-performance devices and make them superior to MESFET's, especially in digital circuits.     

GaAs MESFET's by molecular beam epitaxy

The noise performance of "T" shaped Ti/W/Au gate GaAs Schottky-barrier field-effect transistors fabricated on channel layers grown by molecular-beam epitaxy (MBE) is reported. The nominal gate length was about 0.7 µm with a total gate width of 250 µm. Typical noise figure and the associated gain were 1.2 and 14 dB at 4 GHz, and 1.9 and 8.5 dB at 12 GHz. To out knowledge these are the best results reported to date on devices fabricated using MBE-grown GaAs. These preliminary results show the promise of MBE for high-quality GaAs FET's.     

Direct ion-implanted 0.12 μm GaAs MESFET with ft of121 GHz and fmax of 160 GHz

An 0.12 μm gate length direct ion-implanted GaAs MESFET exhibiting excellent DC and microwave characteristics has been developed. By using a shallow implant schedule to form a highly-doped channel and an AsH₃ overpressure annealing system to optimize the shallow dopant profile, the GaAs MESFET performance was further improved. Peak transconductance of 500 mS/mm was obtained at I_ds =380 mA/mm. A noise figure of 0.9 dB with associated gain of 8.9 dB were achieved at 18 GHz. The current gain cutoff frequency f_max of 160 GHz indicates the suitability of this 0.12 μm T-gate device for millimeter-wave IC applications     

大信号设计GaAs MESFET功率合成

利用ＧａＡｓＭＥＳＦＥＴ功率特性的线性化模型，求出ＧａＡｓＭＥＳＦＥＴ近似最佳功率负载阻抗，为利用谐波平衡法计算提供初值。然后，使用自行研制的谐波平衡分析软件包，进行ＧａＡｓＭＥＳＦＥＴ大信号模型参数的提取和非线性电路模拟计算。将两只总栅宽为９．６ｍｍ的ＧａＡｓＭＥＳＦＥＴ管芯，利用内匹配功率合成技术，在Ｃ波段（５．５～５．８ＧＨＺ）制成１ｄＢ压缩功率大于８Ｗ，典型功率增益９ｄＢ的ＧａＡｓＭＥＳＦＥＴ内匹配功率管。     

InGaAs microwave switch transistors for phase shifter circuits

A new InGaAs insulated-gate FET (IGFET) with 1 μm gate length and three different gate widths has been designed, fabricated and characterized as switch devices for microwave control applications in phase shifter circuits. The devices employed a plasma deposited silicon dioxide gate insulator and had multiple air bridged source regions. The details of the DC current-voltage (I-V) characteristics and small signal S-parameter measurements up to 20 GHz are presented. The switch IGFET's had a drain saturation current density of 300 mA/mm gate width with breakdown voltages of higher than 35 V. An insertion loss of 1.0, 0.6, and 0.4 dB at 10 GHz and 1.4, 0.8, and 0.4 dB at 20 GHz have been measured for the 300, 600, and 1200 μm gate width IGFET's, respectively. Equivalent circuit models fitted to the measured S-parameters for IGFET's yielded on-state resistances from 10.7 to 3.3 Ω, off-state resistances from 734.4 to 186.8 R and off-state capacitances from 0.084 to 0.3 pF as the gate width is increased from 300 to 1200 μm The simulation results using IGFET models for the phase shifter circuits indicated a maximum phase error of 0.11°, 0.26°, and 0.479 with 0.74, 0.96, and 1.49 dB maximum insertion loss and greater than 33, 26, and 19 dB return loss for the 11.25°, 22.5°, and 45° phase bits, respectively, over the 9.5-10.5 GHz frequency band     

High-power InP MISFETs

InP MISFETs with SiO2 as the gate insulator and a deep channel recess have been fabricated. At 9 GHz the highest power output with 4 dB gain was 3.5 W/mm gate width with 33% power added efficiency. This power is more than twice that of the best GaAs MESFET.     

A 20 GHz Band 0.5 W GaAs FET Amplifier for Satellite Communications

GaAs FET amplifier modules for 20 GHz band satellite communications have been developed using newly developed power FETs. The deep recess gate structure was adopted in the power FET, which improved both power output capability and power gain. Power added efficiency of 22 percent with more than 1 W power output has been achieved with 3 mm gate width FETs. The amplifier modules containing two-stage internally matched FET's can be hermetically sealed in metal packages. The modules had 8.4-8.9 dB linear gain in the 17.7-18.8 GHz band and 7.9-8.4 dB linear gain in the 18.5-19.6 GHz band. The power output at 1 dB gain compression point was more than 0.5 W. The third-order intermodulation distortion ratio was 81-83 dB at 18.2 GHz and 77-80 dB at 18.9 GHz, when individual output signal power was -4 dBm.     

基于InGaP/GaAs HBT的X波段MMIC功率放大器研制

研制了X波段的InGaP/GaAs HBT单级MMIC功率放大器,该电路采用自行开发的GaAs HBT自对准工艺技术制作.电路偏置于AB类,小信号S参数测试在8～8.5GHz范围内,线性增益为8～9dB,输入驻波比小于2,输出驻波比小于3,优化集电极偏置后,线性增益为9～10dB.在8.5GHz进行连续波功率测试,在优化的负载阻抗条件下,P1dB输出功率为29.4dBm,相应增益7.2dB,相应PAE〉40%,电路的饱和输出功率Psat为30dBm.     

Ka波段PHEMT功率放大器

报道了 Ka波段的 PHEMT功率放大器的设计和研制。 PHEMT器件采用 0 .2 μm栅长的 Φ 76 mm Ga As工艺制作 ,并利用 CAD技术指导材料生长和器件制作。单级的 MIC放大器采用0 .3mm栅宽的 PHEMT,在 34GHz处 ,输出功率 10 0 m W,功率增益 4 d B。     

A 77 GHz mHEMT MMIC Chip Set for Automotive Radar Systems

A monolithic microwave integrated circuit (MMIC) chip set consisting of a power amplifier, a driver amplifier, and a frequency doubler has been developed for automotive radar systems at 77 GHz. The chip set was fabricated using a 0.15 µm gate‐length InGaAs/InAlAs/GaAs metamorphic high electron mobility transistor (mHEMT) process based on a 4‐inch substrate. The power amplifier demonstrated a measured small signal gain of over 20 dB from 76 to 77 GHz with 15.5 dBm output power. The chip size is 2 mm × 2 mm. The driver amplifier exhibited a gain of 23 dB over a 76 to 77 GHz band with an output power of 13 dBm. The chip size is 2.1 mm × 2 mm. The frequency doubler achieved an output power of –6 dBm at 76.5 GHz with a conversion gain of ?16 dB for an input power of 10 dBm and a 38.25 GHz input frequency. The chip size is 1.2 mm × 1.2 mm. This MMIC chip set is suitable for the 77 GHz automotive radar systems and related applications in a W‐band.     

GaAs microwave power FET with polyimide overlay interconnection

An overlay interconnection technology has been developed for GaAs microwave power FETs, using polyimide as an insulator. An output power of 1017 mW at 4.3 dB gain was achieved at 8 GHz with 27° power added efficiency from a device with a gate width of 1.2 mm. Comparison with devices without overlay interconnection and having a narrower gate width revealed no evidence for degradation in device performance attributable to the interconnection technology.     

High microwave and ultra-low noise performance of fullyion-implanted GaAs MESFETs with Au/WSiN T-shaped gate

Fully ion-implanted n⁺ self-aligned GaAs MESFETs with high microwave and ultra-low-noise performance have been fabricated. T-shaped gate structures composed of Au/WSiN are employed to reduce gate resistance effectively. A very thin and high-quality channel with high carrier concentration can be formed by adopting the optimum annealing temperature for the channel, and the channel surface suffers almost no damage by using ECR plasma RIE for gate formation. GaAs MESFETs with a gate length as short as 0.35 μm demonstrated a maximum oscillation frequency of 76 GHz. At an operating frequency of 18 GHz, a minimum noise figure of 0.81 dB with an associated gain of 7.7 dB is obtained. A K_f factor of 1.4 estimated by Fukui's noise figure equation, which is comparable to those of AlGaAs/GaAs HEMTs with the same geometry, reveals that the quality of the channel is very high     

Ku波段20W GaAs功率PHEMT

报道了采用介质辅助T型栅工艺研制的GaAs功率PHEMT.在该T型栅工艺中栅长和栅帽的尺寸分别进行控制,实现了较好的工艺可控性和较高的工艺成品率.采用该工艺制作了总栅宽为19.2mm的功率PHEMT.用两枚这种芯片合成并研制的Ku波段内匹配功率管在14.0～14.5GHz频带内,输出功率大干20W,功率增益大于6dB,典型功率附加效率为31%.     

A high aspect ratio design approach to millimeter-wave HEMT structures

In MESFET and HEMT structures as the gate length is reduced below 0.5 µm in an attempt to achieve amplification at highest possible frequencies, it is essential that the depletion depth under the gate be also reduced in order to preserve a high aspect ratio that ensures a high device voltage gain factor (gm/g0) and a reasonable value of stable power gain at high frequencies. Results based on this design approach indicate that an n-A1GaAs/GaAs HEMT structure with 0.25-µm gate length could provide stable power gain in excess of 6 dB at the unity current gain frequency of 92.4 GHz, and for an aspect ratio of ten it is difficult to reduce the gate length below 0.25 µm.     

2～8 GHz微波单片可变增益低噪声放大器

报道了一种微波宽带 Ga As单片可变增益低噪声放大器芯片。该芯片采用南京电子器件研究所 76mm圆片 0 .5μm PHEMT标准工艺制作而成。工作频率范围为 2～ 8GHz,在零衰减时 ,整个带内增益大于 2 5d B,噪声系数最大为 3 .5 d B,增益平坦度小于± 0 .75 d B,输入驻波小于 2 .0 ,输出驻波小于 2 .5 ,输出功率大于 1 0d Bm。放大器增益可控大于 3 0 d B。实验发现 ,芯片具有良好的温度特性。该芯片面积为 3 .6mm× 2 .2 mm。