A 77-GHz MMIC power amplifier for automotive radar applications

A MMIC 77-GHz two-stage power amplifier (PA) is reported in this letter. This MMIC chip demonstrated a measured small signal gain of over 10 dB from 75 GHz to 80 GHz with 18.5-dBm output power at 1 dB compression. The maximum small signal gain is above 12 dB from 77 to 78 GHz. The saturated output power is better than 21.5 dBm and the maximum power added efficiency is 10% between 75 GHz and 78 GHz. This chip is fabricated using 0.1-/spl mu/m AlGaAs/InGaAs/GaAs PHEMT MMIC process on 4-mil GaAs substrate. The output power performance is the highest among the reported 4-mil MMIC GaAs HEMT PAs at this frequency and therefore it is suitable for the 77-GHz automotive radar systems and related transmitter applications in W-band.     

An ultra-low power InAs/AlSb HEMT Ka-band low-noise amplifier

The first antimonide-based compound semiconductor (ABCS) MMIC, a Ka-Band low-noise amplifier using 0.25-/spl mu/m gate length InAs/AlSb metamorphic HEMTs, has been fabricated and characterized on a 75 /spl mu/m GaAs substrate. The compact 1.1 mm/sup 2/ three-stage Ka-band LNA demonstrated an average of 2.1 dB noise-figure between 34-36 GHz with an associated gain of 22 dB. The measured dc power dissipation of the ABCS LNA was an ultra-low 1.5 mW per stage, or 4.5 mW total. This is less than one-tenth the dc power dissipation of a typical equivalent InGaAs/AlGaAs/GaAs HEMT LNA. Operation with degraded gain and noise figure at 1.1 mW total dc power dissipation is also verified. These results demonstrate the outstanding potential of ABCS HEMT technology for mobile and space-based millimeter-wave applications.     

30-GHz-band over 5-W power performance of short-channel AlGaN/GaN heterojunction FETs

This paper describes the small-signal characterization through delay-time analysis and high-power operation of the Ka-band of AlGaN/GaN heterojunction field-effect transistors (FETs). An FET with a gatewidth of 100 /spl mu/m and a gate length of 0.09 /spl mu/m has exhibited a current gain cutoff frequency (f/sub T/) of 81 GHz, a maximum frequency of oscillation (fmax) of 187 GHz, and a maximum stable gain of 10.5 dB at 30 GHz (8.3 dB at 60 GHz). Delay-time analysis has demonstrated channel electron velocities of 1.50/spl times/10/sup 7/ to 1.75/spl times/10/sup 7/ cm/s in a gate-length range of 0.09-0.25 /spl mu/m. State-of-the-art performance-saturated power of 5.8 W with a linear gain of 9.2 dB and a power-added efficiency of 43.2%-has been achieved at 30 GHz using a single chip having a gatewidth of 1.0 mm and a gate length of 0.25 /spl mu/m.     

GaAs heterostructure FET frequency dividers fabricated with high-yield 0.5 mu m direct-write trilevel-gate-resist

Frequency dividers and FET test structures have been fabricated on selectively doped n/sup +/AlGaAs/GaAs heterostructure FETs (HFETs) with 0.5 mu m gate length electron-beam direct-writing on a novel trilevel resist, EBR-9/Ge/PMGI. A divide-by-two master-slave frequency divider fabricated with direct-coupled FET logic gates operated up to 9.3 GHz. The input frequency range of a divide-by-two transmission-gate frequency divider was from 3.2 to 12.2 GHz, with a supply voltage of 1.2 V at room temperature. The average propagation delay (fan-in and fan-out=1) was 18.2 ps/gate, with a power dissipation of 3.9 mW/stage. With a 3.5 mu m source-drain spacing, a peak transconductance of 360 mS/mm was measured. The functional yield of both discrete devices and circuits was 92% across 2 in-diameter wafers.<>     

Enhanced microwave performance of ion-implanted MESFET with graded GaAs/AlGaAs heterojunctions

Ion-implanted MESFETs have been fabricated on an inverted GaAs/AlGaAs heterostructure. The aluminium concentration in the AlGaAs is graded from 0% at the substrate to 30% at the heterointerface. A maximum extrinsic transconductance of 410 mS/mm is achieved with 0.5 mu m gate devices. This heterojunction ion-implanted FET (HIFET) also exhibits enhanced microwave performance, especially at low drain current, when compared to conventional ion-implanted GaAs MESFETs. At 20% of I/sub dss/, the current gain cutoff frequency f/sub t/ is 40 GHz, which increases up to a maximum value of 47 GHz as the drain current rises. These characteristics of high f/sub t/ and high gain at low current are advantageous for low-noise applications.<>     

Noise parameters for design of MMIC HEMT LNA

The letter gives the noise parameters of MOVPE HEMTs or the design of MMIC HEMT low-noise amplifiers. An example of the design of an HEMT LNA is given using these parameters. The MMIC LNA has been fabricated and exhibits a 2.3+or-0.2 dB noise figure with an associated gain of 12+or-2 dB in the 12-16 GHz frequency range. The measured performance is within 0.5 dB of the simulation.<>     

High performance of induced-channel heterojunction field-effect transistor (HFET)

AlGaAs/GaAs high-performance, minority-carrier, induced-channel, heterojunction field-effect transistors (HFETs) fabricated on semi-insulating GaAs using molecular beam epitaxy (MBE) are reported. A 0.6 mu m self-aligned gate HFET exhibited a room-temperature transconductance of 540 mS/mm with a cutoff frequency of 25 GHz.<>     

Dual-gate AlGaN/GaN modulation-doped field-effect transistors with cut-off frequencies f/sub T/>60 GHz

We demonstrate dual-gate AlGaN/GaN modulation-doped field-effect transistors (MODFETs) with gate-lengths of 0.16 /spl mu/m and 0.35 /spl mu/m for the first and second gates, respectively. The dual-gate device exhibits a current-gain cut-off frequency f/sub T/>60 GHz, and can simultaneously achieve a high breakdown voltage of >+100 V. In comparison to single-gate devices with the same gate length 0.16 /spl mu/m, dual-gate FETs can significantly increase breakdown voltages, largely increasing the maximum allowable drain bias for high power application. The continuous wave (CW) output power is in excess of 3.5 W/mm at 8.2 GHz. The corresponding large-signal gain is 12 dB and the power added efficiency is 45%. The dual-gate device with different gate lengths shows the capability of providing simultaneous high cut-off frequencies, and high breakdown voltages for broadband power amplifiers.     

Low-noise HEMT using MOCVD

Low-noise HEMT AlGaAs/GaAs heterostructure devices have been developed using metal organic chemical vapor deposition (MOCVD). The HEMT's with 0.5-µm-long and 200-µm-wide gates have shown a minimum noise figure of 0.83 dB with an associated gain of 12.5 dB at 12 GHz at room temperature. Measurements have confirmed calculations on the effect of the number of gate bonding pads On the noise figure for different gate Widths. Substantial noise figure improvement was observed Under low-temperature operation, especially compared to conventional GaAs MESFET's. A two-stage amplifier designed for DBS reception using the HEMT in the first stage has displayed a noise figure under 2.0 dB from 11.7 to 12.2 GHz.     

A Compact Broadband PHEMT MMIC Power Amplifier for K through Ka-band Applications

A compact and broadband MMIC power amplifier operating from 18 GHz to 35 GHz is developed for K- through Ka-band applications implementing a rigorous electromagnetic (EM) simulation of closely spaced matching networks. The EM simulation results in a compact chip size as small as 2.16 mm × 2.0 mm and isolations of less than -25 dB up to 40 GHz between neighboring distributed structures. The two-stage balanced power amplifier fabricated using a 0.25 µm AlGaAs/InGaAs/GaAs PHEMT technology has an average gain of 11 dB, return losses less than -10 dB, and P1 dB above 20.5 dBm from 18 GHz to 35 GHz. This compact and broadband MMIC power amplifier is suited for power amplifiers for most K through Ka-band communication systems such as the FSS, LMDS, and ITS.     

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.     

Gallium arsenide MBE structure comprising mixer diodes and FETs for monolithic millimetre-wave receivers

The formation of millimetre-wave GaAs mixer diodes and 0.5 mu m gate FETs on the same wafer has been demonstrated using a three-layer MBE structure. The diodes have a measured cut-off frequency of 780 GHz and the FETs typically exhibit f/sub max/ greater than 50 GHz. This technology is suitable for the implementation of monolithic microwave and millimetre-wave receivers.<>     

Ultra low noise characteristics of AlGaAs/InGaAs/GaAs pseudomorphicHEMT's with wide head T-shaped gate

The fully passivated low noise AlGaAs/InGaAs/GaAs pseudomorphic (PM) HEMT with 0.13 μm T-shaped gate was fabricated using dose split electron beam lithography method (DSM). This device exhibited low noise figures of 0.31 and 0.45 dB at 12 and 18 GHz, respectively. These noise figures are the lowest value ever reported for the GaAs based HEMT's. These results are attributed to the extremely low gate resistance which results from wide head T-shaped gate having the higher ratio more than 10 of gate head length to gate footprint     

Ultra-high gain, low noise monolithic InP HEMT distributed amplifier from 5 to 40 GHz

A monolithic 5-45 GHz distributed amplifier has been developed utilising 0.25 mu m InAlAs/InGaAs lattice matched HEMTs with a mushroom gate profile as active devices. A measured gain of 12.5+or-0.5 dB from 5 to 40 GHz and a measured noise figure of 2.5-4 dB in the Ka-band were achieved.<>     

A study of high-speed normally off and normally on Al0.5Ga0.5As heterojunction gate GaAs FET's (HJFET)

The dc, small-signal microwave, and large-signal switching performance of normally off and normally on Al0.5Ga0.5As gate heterojunction GaAs field-effect transistors (HJFET) with submicrometer gate lengths are reported. The structure of both types of devices comprises an n-type 10¹⁷-cm^-3Sn-doped active layer on a Cr-doped GaAs substrate, a p-type 10¹⁸-cm^-3Ge-doped Al0.5Ga0.5As gate layer and a p⁺-type 5 × 10¹⁸-cm^-3Ge-doped GaAs "contact and cap" layer on the top of the gate. The gate structure is obtained by selectively etching the p⁺-type GaAs and Al0.5Ga0.5As. Undercutting of the Al0.5Ga0.5As layer results in submicrometer gate lengths, and the resulting p⁺-GaAs overhang is used to self-align the source and the drain with respect to the gate. Normally off GaAs FET's with 0.5- to 0.7-µm long heterojunction gates exhibit maximum available power gains (MAG) of about 9 dB at 2 GHz. Large-signal pulse measurements indicate an intrinsic propagation delay of 40 ps with an arbitrarily chosen 100-Ω drain load resistance in a 50-Ω microstrip circuit. Normally on FET's with submicrometer gate lengths (∼0.6 µm) having a total gate periphery of 300 µm and a corresponding dc transconductance of 20-30 mmhos exhibit a MAG of 9.5 dB at 8 GHz. The internal propagation delay time measured under the same conditions as above is about 20 ps.     

16*16 bit parallel multiplier based on 6 K gate array with 0.3 mu m AlGaAs/GaAs quantum well transistors

The design and performance of a 16*16 bit parallel multiplier based on a 6 K gate array will be presented. This LSI semicustom IC demonstrates the high potential of the authors' AlGaAs/GaAs quantum well FETs with a gate length of 0.3 mu m. The best multiplication time measured was 7.2 ns.<>     

Application of heterojunction FET to power amplifier for cellulartelephone

The high power properties of heterojunction FETs (H-FET have been investigated. The H-FETs are fabricated by using a strained AlGaAs/GaInAs/GaAs/AlGaAs selectively-doped double heterojunction structure. As compared with GaAs MESFETs, the H-FETs show 1.5 dB higher saturation power and 8% higher power-added efficiency than those of the MESFETs, at 950 MHz and 4.7 V. The H-FETs are more suitable for the power amplifier of cellular telephones     

A 5-10 GHz octave-band AlGaAs/GaAs HBT-Schottky diodedown-converter MMIC

The authors describe an AlGaAs/GaAs heterojunction bipolar transistor (HBT) X-band down-converter monolithic microwave integrated circuit (MMIC) which integrates a double double-balanced Schottky mixer and five stages of HBT amplification to achieve greater than 30 dB conversion gain over an RF bandwidth from 5 to 10 GHz. In addition, an output IP3 as high as +15 dBm has been achieved. The Schottky diodes are constructed from the existing N^$collector and N⁺ subcollector layers of the HBT molecular beam epitaxy (MBE) device structure. A novel HBT amplifier topology employing active feedback which provides wide bandwidth in a compact area is used for the RF, LO, and IF amplifier stages. The complete down-converter MMIC is realized in a 3.6×3.4 mm² area, is self-biased through a 6 V supply, and consumes 530 mW. This MMIC represents the highest complexity X-band down-converter MMIC demonstrated using GaAs HBT-Schottky diode technology     

A novel model of the gate current in heterojunction FETs

The authors present a model of the gate current in heterojunction FETs that takes into account two-dimensional electron gas effects at the heterojunction interface. The gate current results from tunnel and thermionic contributions. This model takes into account a number of technological parameters such as heterojunction barrier height, threshold voltage, gate length, and temperature. It has been tested against experimental measurements of gate current in AlGaAs/GaAs MISFETs at various temperatures. The agreement has been found quite satisfactory in a large range of temperatures     

Super low-noise GaAs MESFET's with a deep-recess structure

Super low-noise GaAs MESFET's for replacement of parametric amplifiers have been successfully developed by adopting a deep-recess structure. The structure of a 0.5-µm gate in a deeply recessed region with a cylindrical edge shape has enabled reduction of the source resistance to a half of that of conventional flat-type MESFET's. The noise figure was improved by more than 0.5 dB by this reduction of the source resistance, and less than 2.0-dB noise figure has been reproducibly obtained at 12 GHz. The best noise figures were 0.7 dB (14.9-dB gain) at 4 GHz and 1.68 dB (10.7-dB gain) at 12 GHz. The developed MESFET's were applied to two-stage amplifiers of 11.7-12.2-GHz band, and the noise figure obtained was 2.16 dB (T_{e}: 185K) at room temperature and 1.94 dB (T_{e}: 163K) at 0°C. This performance is good enough to replace some of parametic amplifiers.