RF Power Performance Research Articles

A novel double-recessed 0.2-μm T-gate process for heterostructure InGaP-InGaAs doped-channel FET fabrication

A double-recessed T-gate process has been successfully developed to fabricate 0.2-/spl mu/m gate-length heterostructure InGaP-InGaAs doped-channel FETs (DCFETs) to increase the gate-to-drain breakdown voltage. This technology uses direct electron-beam lithography with a single exposure of a four-layer stack polymethylmethacrylate and polydimethylmethacrylate (photoresists). After the combination of chemical and dry etchings, the double gate-recessed DCFETs exhibit improved DC and RF power performance, as compared with the conventional ones, resulting from the gate-leakage current. The Schottky gate breakdown voltage enhances from 5 to 7 V, and the output power increases from 148 to 288 mW/mm at 5.2 GHz.

MBE growth of ALGaN/GaN HEMTS on resistive Si(1 1 1) substrate with RF small signal and power performances

In this paper, we report on the properties of GaN films and AlGaN/GaN HEMT structures grown by molecular beam epitaxy on resistive Si(1 1 1) substrates. The properties of the GaN buffer layer and the AlGaN/GaN HEMTs are presented. Finally, both static and high-frequency performances of sub-micron gate length devices are analyzed demonstrating their RF power capability.

AlGaN/GaN HEMTs on Resistive Si(111) Substrate: From Material Assessment to RF Power Performances

In this paper, we report on the properties of GaN films and AlGaN/GaN HEMT structures grown by molecular beam epitaxy on resistive Si(111) substrates. The properties of the GaN buffer layer and the AlGaN/GaN HEMTs are presented. Finally, both static and high frequency performances of submicron gate length devices are analysed demonstrating their RF power capability.

Optimum Au/WSi 0.3 μm-gate-length n-HIGFETs for microwave power applications in X band

An investigation of pseudomorphic Ga/sub 0.25/Al/sub 0.75/As/Ga/sub 0.80/In/sub 0.20/As/GaAs heterostructure insulated-gate FETs (HIGFET) far microwave power applications is presented. Devices have been fabricated using Au/WSi self-aligned gate technology with SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> sidewalls. The fabrication process has been optimized in order to realize 0.3 μm gate-length transistors with reduced short-channel effects and improved rf power performance. dc and rf extracted parameters suggest very attractive capabilities: for N-type HIGFET, a current density of 460 mA/mm and an extrinsic transconductance of 480 mS/mm are obtained. Measurements at 10 GHz using a load-pull power setup have been carried out: 300 mW/mm maximum output power, 14 dB linear gain, and 65% PAE, for low Vds (3 V) value. To our knowledge, these power results are the first reported for 0.3 μm-HIGFFTs.

AlGaAs/InGaAs heterostructure doped-channel FET's exhibiting good electrical performance at high temperatures

High-power and high-efficiency GaAs heterostructure field-effect transistors (FETs) are attracting tremendous attention in RF power amplifier applications. However, thermal effects can be an important issue in RF power devices, owing to the huge amount of heat generated during their operation. In this paper, the temperature-dependent characteristics of Al/sub 0.3/Ga/sub 0.7/As/In/sub 0.15/Ga/sub 0.85/ As doped-channel FETs (DCFETs) are investigated and compared with conventional pseudomorphic-HEMTs (pHEMTs) devices, in terms of their dc, microwave and RF power performance at temperatures ranging from room temperature to 150/spl deg/C. Due to conducting carriers being less influenced by temperature and the better Schottky diode characteristics that can be obtained in DCFETs, the intrinsic device parameters and output performance remain almost constant at high temperatures, which also results in better device reliability. The performance variation of DCFETs associated with temperatures from 25/spl deg/C to 150/spl deg/C all fall within a single digit, i.e., output power (P/sub out/, 16.2 dBm versus 15.8 dBm), power gain (G/sub p/, 16.6 dB versus 15.1 dB), power added efficiency (PAE, 34.2% versus 31.3%), which is not the case for conventional pHEMTs. Therefore, DC devices are very promising for microwave power device applications operating at high temperature.

Wide bandgap semiconductor transistors for microwave power amplifiers

Explores the RF power performance of microwave amplifiers fabricated from wide bandgap semiconductor transistors and demonstrates that microwave power amplifiers fabricated from 4H-SiC and AlGaN/GaN transistors offer superior RF power performance, particularly at elevated temperatures. Theoretical models predict room temperature RF output power on the order of 4-6 W/mm and 10-12 W/mm, with power-added efficiency (PAE) approaching the ideal values for class A and B operation, available from 4H-SiC MESFETs and AlGaN/GaN HFETs, respectively. All calculations were thoroughly calibrated against dc and RF experimental data. The simulations indicate operation at elevated temperature at least up to 5000/spl deg/C is possible. The RF output power capability of these devices compares very favorably with the 1 W/mm available from GaAs MESFETs. The wide bandgap semiconductor devices will find application in power amplifiers for base station transmitters for wireless telephone systems, HDTV transmitters, power modules for phased-array radars, and other applications. The devices are particularly attractive for applications that require operation at elevated temperature.

AlGaN Microwave Power HFETs on Insulating SiC Substrates

ABSTRACTAIGaN HFETs are attractive devices for high power microwave applications. Sapphire, which is the typical substrate for AlGaN epitaxy, has a very poor thermal conductivity, and the power performance of AlGaN HFETs fabricated on sapphire substrates is severely limited due to this large thermal impedance. We report on HFETs fabricated on high thermal conductivity electrically insulating SiC substrates. Excellent RF power performance for large area devices is demonstrated. On-wafer CW measurements at 10 GHz of a 320 micron wide FET resulted in an RF power density of 2.8 Watts/mm, and measurements of a 1280 micron wide FET resulted in a total power of 2.3 Watts. On-wafer pulsed measurements, at 8 GHz, of a 1280 micron wide FET resulted in a total power of 3.9 Watts. Design of a hybrid microwave amplifier will be discussed.

High power applications for GaN-based devices

The microwave performance potential of electronic devices fabricated from GaN-based semiconductors is described. The investigation makes use of theoretical simulations and the results are compared to experimental measurements. Excellent agreement between the simulated and measured data is obtained. It is demonstrated that devices fabricated from these semiconductors make possible microwave power amplifiers with superior RF power performance, particularly at elevated temperature, compared to comparable components fabricated from GaAs MESFET's. In particular, room temperature RF output power on the order of 4–5 W mm −1 of gate periphery with power-added efficiency approaching the ideal values for class A and B operation is available. These devices are likely to find application in power amplifiers for base stations transmitters for cellular telephone systems, HDTV transmitters, power modules for phased-array radars, and other applications. The devices are particularly attractive for applications that require high RF output power and operation at elevated temperature since cooling requirements can be minimized or eliminated.

Silicon Carbide And Gallium Nitride Rf Power Devices

AbstractImpressive RF power performance has been demonstrated by three radically different wide bandgap semiconductor power devices, SiC MESFET's, SiC SIT's, and AlGaN HFET's. AlGaN HFET's have achieved the highest fmax 97 GHz. 4H-SiC MESFET's have achieved the highest power densities, 3.3 W/mm at 850 MHz (CW) and at 10 GHz (pulsed). 4H-SiC SIT's have achieved the highest output power, 450 W (pulsed) at 600 MHz and 38 W (pulsed) at 3 GHz. Moreover a one kilowatt, 600 MHz SiC power module containing four multi-cell SIT's with a total source periphery of 94.5 cm has been demonstrated.

Highpower 0.15-mm V-band pseudomorphic InGaAs-AlGaAs-GaAs HEMT

The DC and RF power performance of double heterostructure pseudomorphic InGaAs-AlGaAs-GaAs HEMTs at V-band is reported. A 0.15-mm*400-mm device has demonstrated output power of 225 mW (0.55 W/mm) with 4.5-dB power gain and 25.4% power-added efficiency (PAE) at 60 GHz. A 0.15-mm*320-mm device demonstrated 31.1% PAE with 170-mW (0.53 W/mm) output power and 5.3-dB power gain. These data represent the highest reported combination of output power, power gain and power-added efficiency for a single device at V-band. >

InGaAs field-effect transistors with submicron gates for K-band applications

Depletion mode InGaAs microwave power MISFETs with 0.7 mu m gate lengths and 0.2 mm gate widths have been fabricated using an epitaxial process. The devices employed a plasma deposited silicon dioxide gate insulator. The RF power performance at 18 GHz, 20 GHz, and 23 GHz is presented. An output power density of 1.04 W/mm with a corresponding power gain and power-added efficiency of 3.7 dB and 40%, respectively, was obtained at 18 GHz. This is the highest output power density obtained for an InGaAs based transistor on InP at K-band. Record output power densities for an InGaAs MISFET were also demonstrated to the stable within 3% over 17 hours of continuous operation at 18 GHz.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Indium gallium arsenide microwave power transistors

Depletion-mode InGaAs microwave power MISFETs with 1- mu m gate lengths and up to 1-mm gate widths have been fabricated using an ion-implanted process. The devices employed a plasma-deposited silicon/silicon dioxide gate insulator. The DC current-voltage (I-V) characteristics and RF power performance at 9.7 GHz are presented. The output power, power-added efficiency, and power gain as a function of input power are reported. An output power of 1.07 W at 9.7 GHz with a corresponding power gain and power-added efficiency of 4.3 dB and 38%, respectively, was obtained. The large-gate-width devices provided over twice the previously reported output power for InGaAs MISFETs at X-band. In addition, the first report of RF output stability of InGaAs MISFETs over 24 h period is also presented. An output power stability within 1.2% over 24 h of continuous operation was achieved. In addition, a drain current drift of 4% over 10/sup 4/ s was obtained. >

High-power V-band pseudomorphic InGaAs HEMT

The author's present the DC and RF power performance of planar-doped channel InGaAs high-electron-mobility transistors (HEMTs). The planar-doped channel (PDC) pseudomorphic GaAs HEMT with 400 mu m of gate width exhibited an output power of 184 mW, corresponding to 460 mW/mm, with 4.6-dB saturation gain and 25% power-added efficiency at 55 GHz. Although higher power density is possible, the authors have designed the device to operate at less than 500 mW/mm for thermal and reliability reasons. Devices with unit gate finger widths ranging from 30 to 50 mu m were fabricated and characterized, with no performance degradation observed from using the longer gate fingers.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

High-efficiency 0.25- mu m gate-length pseudomorphic power heterostructure FETs at millimeter-wave frequencies

The authors compare the 35-GHz power performance of four different 0.25- mu m gate-length pseudomorphic AlGaAs/InGaAs/GaAs heterostructure FET (HFET) devices. The devices that are examined include the HEMT (high-electron-mobility transistor), double-heterojunction HEMT (DHHEMT), doped-channel HFET (DCHFET), and the doped-channel MODFET (DCHMODFET). A maximum 35-GHz power-added-efficiency and a power density of 49% and 0.94 W/mm were measured, for the DCHMODFET; 43% and 0.97 W/mm for the DHHEMT, 32% and 0.75 W/mm for the HEMT, and 31% and 0.77 W/mm for the DCHFET. The DC parameters that influence RF power performance were analyzed, and it was found that the I-V linearities of the DCHMODFET, DCHFET, and DHHEMT are much better than that of the HEMT and that the pinchoff characteristics of the DCHMODFET are superior to those of the DHHEMT. The first point explains why the efficiencies of the DCHMODFET and DHHEMT are significantly better than that of the HEMT. It is believed that the second point is responsible for the better efficiency in the DCHMODFET compared to the DHHEMT.