E-mode pHEMT Research Articles

A Compact 1.0–12.5-GHz LNA MMIC With 1.5-dB NF Based on Multiple Resistive Feedback in 0.15-μm GaAs pHEMT Technology

In this paper, a 2-stage compact wideband low-noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) with multiple resistive feedback (MRFB) is presented. From the DC point of view, the proposed MRFB functions as a self-biasing structure to bias transistors in the optimal condition, improving the noise figure (NF) and linearity. Meanwhile, by employing MRFB with source degeneration and input inductor, the proposed LNA achieves wideband flat gain at the AC side. In comparison with traditional topologies, a wide bandwidth of more than 11.5 GHz with low noise figure of less than 2.5 dB can be achieved. To verify the proposed LNA structure, a chip prototype is fabricated in a 0.15- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> GaAs E-mode pHEMT process with a compact die size of only 0.75 mm2 including all the testing pads. From the measurement results, the proposed LNA circuit features a 1.0 to 12.5 GHz 3-dB working bandwidth (172% fractional bandwidth), 23.6 peak gain, 1.51 dB minimum NF, 66.7± 15 ps group delay, and 24.3/12.6 dBm best OIP3/OP1dB, respectively. The total DC power is around 87.5 mW from a single 2.5-V power supply.

A 9-to-42-GHz High-Gain Low-Noise Amplifier Using Coupled Interstage Feedback in 0.15-μm GaAs pHEMT Technology

This article presents a 3-stage millimeter-wave low-noise amplifier (LNA) monolithic microwave integrated circuit (MMIC) design for broadband applications. The proposed structure consists of cascading common-source (CS) LNA with coupled interstage feedback (CIF) paths at the second and third stages. By tuning the coupling factor and the inductance of the CIF, enhanced overall gain and extended working bandwidth can be achieved simultaneously. The proposed CIF formed by a simple on-chip edge-coupled parallel metal-lines features small size and high flexibility. To facilitate circuit design and optimization, an equivalent circuit for the proposed CIF structure is developed. Besides, to address the trade-off between impedance matching and noise performance, a noise matching strategy focusing more on higher frequencies is presented to achieve good noise performance. With the proposed techniques, an LNA prototype is demonstrated in a commercial 0.15- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> GaAs E-mode pHEMT process. The fabricated LNA has a die size of 1.15 mm2 and DC power consumption of 109 mW. The measurement results show a peak gain of 25.6 dB with a 3-dB bandwidth of 9~42 GHz, the minimal noise figure (NF) of 1.91 dB, a group delay of 68.7± 20.5 ps, and 20.8 dBm best OIP3 under 2.0-V VDD.

Design and Analysis of a Cascode Distributed LNA With Gain and Noise Improvement in 0.15-μm GaAs pHEMT Technology

This brief presents a 2.0~42.0 GHz ultra-wide bandwidth Cascode distributed low-noise amplifier (CDLNA) MMIC design. With the proposed coupled-line (CL) sections between each drain-artificial transmission line (D-ATML) node and related gate-artificial transmission line (G-ATML) node, the traveling signal is reused to enhance the gain and broaden the operation bandwidth simultaneously. To improve the gain further, the inductive gain peaking has also been employed at each drain of common-source (CS) and common-gate (CG) transistors. Meanwhile, an active termination technique incorporating active and passive elements has been adopted to achieve better noise figure (NF) performance. Employing the proposed techniques, an LNA prototype has been designed and fabricated in a 0.15- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> GaAs E-Mode pHEMT technology with the chip size of 1.53 mm2 including all the pads. From test results, the proposed CDLNA demonstrates a peak gain of 14.1 dB, the best NF of 2.1 dB, a group delay of 102 ± 58.4 ps, and 23.25/14.7 dBm best OIP3/OP1dB, respectively. The total power consumption is 129 mW under 3 V VDD.

X-band monolithic three-stage LNA with GaAs E-mode PHEMT

An LNA for 8∼12 GHz is proposed in this paper. The amplifier uses a GaAs process with cost-effective, E-mode HEMTs with gate widths of 0.25 µm and 0.45 µm. The three stages of the LNA are powered by dual power supplies, with a drain operating voltage of +3V and a gate operating voltage of +0.7V. The simulation results of the schematic diagram show that the noise factor of the low-noise amplifier is less than 2.5dB in the frequency range of 8-12GHz, the in-band gain is greater than 30dB, the gain flatness is ±1.5dB, the 1dB compression point is 7dbm, the VSWRs are less than -10dB, and the LNA is absolutely stable in the X-band.

A 15 Gbps-NRZ, 30 Gbps-PAM4, 120 mA laser diode driver implemented in 0.15-µm GaAs E-mode pHEMT technology

This paper presents the design and testing of a 15 Gbps non-return-to-zero (NRZ), 30 Gbps 4-level pulse amplitude modulation (PAM4) configurable laser diode driver (LDD) implemented in 0.15-µm GaAs E-mode pHEMT technology. The driver bandwidth is enhanced by utilizing cross-coupled neutralization capacitors across the output stage. The output transmission-line back-termination, which absorbs signal reflections from the imperfectly matched load, is performed passively with on-chip 50-Ω resistors. The proposed 30 Gbps PAM4 LDD is implemented by combining two 15 Gbps-NRZ LDDs, as the high and low amplification paths, to generate PAM4 output current signal with levels of 0, 40, 80, and 120 mA when driving 25-Ω lasers. The high and low amplification paths can be used separately or simultaneously as a 15 Gbps-NRZ LDD. The measurement results show clear output eye diagrams at speeds of up to 15 and 30 Gbps for the NRZ and PAM4 drivers, respectively. At a maximum output current of 120 mA, the driver consumes 1.228 W from a single supply voltage of –5.2 V. The proposed driver shows a high current driving capability with a better output power to power dissipation ratio, which makes it suitable for driving high current distributed feedback (DFB) lasers. The chip occupies a total area of 0.7 × 1.3 mm2.

Analysis and Design of a Broadband Receiver Front End for 0.1-to-40-GHz Application

In this paper, a broadband receiver front end for 0.1 to 40 GHz application, fabricated using 0.15-μm GaAs E-mode pHEMT process, is reported. The receiver front end consists of a broadband low-noise amplifier (LNA) and a broadband mixer. To achieve low noise and significant bandwidth extension, a three-stage LNA, cascading one stage cascode amplifier with feedback and bandwidth extension techniques, to two stage cascode Darlington amplifiers with feedback, is proposed. The bandwidth extension principles of LNA are analyzed theoretically and verified experimentally. Measurement results show that the proposed LNA exhibits an average gain of 23.7 dB with ± 1.5-dB variation, a typical noise figure of 3.8 dB, maximum OP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> of 8.7 dBm in the frequency range from 0.1 to 40 GHz. A symmetric distributed drain mixer (SDDM) is proposed to provide broad bandwidth while ensuring an IP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> of up to 5.8 dBm. The design procedure of SDDM is presented in detail. Experimental results indicate that the SDDM features a less than 7-dB conversion loss, an IP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1dB</sub> of up to 5.8 dBm with zero dc dissipation and better than 15-dB isolation of LO-to-RF and IF-to-RF ports from 0.1 to 40 GHz. Finally, the LNA and SDDM are integrated as a 0.1 to 40-GHz receiver front end. Measurements illustrate that the receiver front end shows good matching with better than 10-dB return loss at RF and LO ports, and larger than 15-dB conversion gain in 0.1 to 40-GHz frequency range. The receiver occupies only 1.89-mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> chip area including test pads. To the best of the authors' knowledge, the designed receiver front end has the widest bandwidth among reported receivers fabricated by using GaAs process.

A technique for bandwidth extension and noise optimization of wideband low-noise amplifier with dual feedback loops

A technique for bandwidth extension and noise optimization of wideband low-noise amplifier with dual feedback loops is presented. A LC-ladder matching network has been added in front of conventional amplifier with dual feedback loops. Detailed circuit analysis and general design procedures for the modified amplifier have been provided. The technique is applied to an amplifier covering the frequency range from DC to 6 GHz in a 0.5 μm InGaAs E-mode pHEMT process. Post-layout simulation shows S 11 below ?10 dB, S 22 below ?10 dB, flat S 21 of 16 ± 0.2 dB, and flat NF of 1.85 ± 0.35 dB across the entire band, which confirms the improvement in bandwidth and noise performance.

Novel GaAs enhancement-mode/depletion-mode pHEMTs technology using high-k praseodymium oxide interlayer

In this study, a novel metal–semiconductor gate enhancement-mode (E-mode) and a metal–insulator-metal–semiconductor (MIMS) gate depletion-mode (D-mode) AlGaAs/InGaAs pseudomorphic high electron mobility transistor (pHEMT) on a single GaAs substrate have been developed by using high dielectric constant praseodymium insulator layer. The epitaxial layers were design for an enhancement-mode pHEMT after gate recess process. To achieve E/D-mode pHEMTs on single GaAs wafer, traditional Pt/Ti/Au metals were deposited as Schottky contact for E-mode pHEMTs and Pr/Pr 2O 3/Ti/Au were deposited as MIMS-gate for D-mode pHEMTs. This AlGaAs/InGaAs E-mode pHEMTs exhibit a gate turn-on voltage ( V ON) of +1 V and a gate-to-drain breakdown voltage of −5.6 V, and these values were +7 V and −34 V for MIMS-gate D-mode pHEMTs, respectively. Therefore, this high-k insulator in D-mode pHEMT is beneficial for suppressing the gate leakage current. Comparing to previous E/D-mode pHEMT technology, this E-mode pHEMTs and MIMS-gate D-mode pHEMTs exhibit a highly potential for high uniformity GaAs logic circuit applications due to its single recess process.

Voltage-controlled oscillator phase-noise improvement using a GaAs 0.5 µm Pt-buried gate enhancement-mode pHEMT

This paper presents a voltage-controlled oscillator (VCO) with low phase-noise performance by employing the Pt-buried gate process in enhancement-mode (E-mode) pHEMT technology. After the 4 h stabilization bake process, Pt diffuses into an AlGaAs Schottky layer to form a PtAs2 amorphous layer and native dangling bonds in AlGaAs can be eliminated to improve surface flicker noise. To further evaluate the Pt/AlGaAs interface stability at continuous waveform output operation, the cross-coupled 9 GHz VCO with an E-mode pHEMT (Pt/Ti/Pt/Au gate) and depletion-mode (D-mode) pHEMTs was designed and fabricated in a 0.5 µm gate length 6 inch GaAs wafer simultaneously. The measured phase noise of the Pt-buried gate E-mode pHEMT VCO is −126 dBc Hz−1 at the 1 MHz offset frequency. Compared to the D-mode pHEMT VCO, this novel design achieved an average 10 dB phase-noise improvement at the offset frequency from 100 kHz to 10 MHz.

A 38% Tuning Bandwidth Low Phase Noise Differential Voltage Controlled Oscillator Using a 0.5 $\mu$m E/D-PHEMT Process

This paper presents a 38% tuning bandwidth low phase noise differential voltage controlled oscillator (VCO) using a 0.5 mum enhancement/depletion-pseudomorphic high-electron mobility transistor (E/D-PHEMT) process. The proposed VCO is based on a differential topology with two common-gate transistors. To achieve a wide tuning range with low phase noise, varactor in the VCO core employs the E-mode PHEMT device. The frequency of the VCO is from 18.8 to 27.5 GHz with a tuning bandwidth of 38% and an output power of higher than 5 dBm. The VCO demonstrates a phase noise of -109 dBc/Hz at 1 MHz offset frequency. This circuit can be compared with the VCOs fabricated using the advanced InP HBT technologies.

A 30–130 GHz Ultra Broadband Direct-Conversion BPSK Modulator Using a 0.5-$\mu$m E/D-PHEMT Process

A 30-130 GHz ultra broadband direct-conversion binary phase shift keying (BPSK) modulator using a 0.5-mum enhancement/depletion-pseudomorphic high-electron mobility transistor (E/D-PHEMT) process is presented in this letter. The BPSK modulator was designed using a modified reflection-type topology with E-mode PHEMT devices. An advantage for the E-mode PHEMT process is positive gate bias, and therefore the bias circuit for the modulation would be less complicated. Moreover, the BPSK modulator demonstrates an error vector magnitude of within 5.5%, an adjacent channel power ratio of better than -35 dBc, and an on-off isolation of greater than 20 dB from 30 to 130 GHz. The chip size of the BPSK modulator is only 0.8x0.7 mm2. To the best of the authors' knowledge, this work is the highest operation frequency with the widest bandwidth among all the reported monolithic microwave integrated circuit-based BPSK modulators.

The study of δ-doped InGaP/InGaAs/GaAs pseudomorphic high electron mobility transistor

An enhancement-mode pseudomorphic high electron mobility transistor (E-mode pHEMT) with In0.49Ga0.51P/In0.25Ga0.75As/GaAs structure is studied in this paper. The two-dimensional device simulator, MEDICI, is used to solve the Poisson's equation and the electron/hole current continuity equations. An optimized δ-doped InGaP/InGaAs pHEMT structure is found to be superior to the conventional AlGaAs/InGaAs pHEMT. It reveals that the maximum drain-source current (IDS) goes up to 1600mA/mm and transconductance (Gm) is 2120mS/mm.

Microwave Performance of ( Al0.3Ga0.7 ) 0.5In0.5P , In0.5Ga0.5P , Al0.28Ga0.72As Enhancement-Mode Pseudomorphic HEMT with Succinic Acid Gate Recess Process

, , compounds on GaAs substrates are important materials that are used as Schottky layers in microwave transistors. This study systematically explores the electrical characteristics of various enhancement-mode pseudomorphic high electron mobility transistors (E-mode pHEMTs) with , , Schottky layers. These E-mode pHEMTs were fabricated using a high-selectivity succinic acid solution for gate recess and buried-Pt gate technology. The E-mode pHEMT has a Schottky diode turn-on voltage of . The corresponding values for and E-mode pHEMTs are 0.72 and , respectively. Because a larger can be obtained at the interface, the E-mode pHEMT also more effectively confined carriers and yielded a higher sheet charge density than other Schottky materials. Based on these measured results, this E-mode pHEMT is more appropriate for microwave low-noise and high-power device applications.

High Uniformity ( Al0.3Ga0.7 ) 0.5In0.5P / InGaAs Enhancement-Mode Pseudomorphic HEMTs by Selective Succinic Acid Gate Recess

High selectivity succinic acid: H 2 O 2 solution (SA) wet etching processes were used in the gate recess process to fabricate (Al 0 . 3 Ga 0 . 7 ) 0 . 5 In 0 . 5 P quaternary enhancement-mode pseudomorphic high electron mobility transistors (E-mode pHEMT). High uniformity of threshold voltage (V t h ) was achieved due to a high wet etching selectivity during gate recess process. In this study, we improved the power density and uniformity of the device by using wide bandgap (Al 0 . 3 Ga 0 . 7 ) 0 . 5 In 0 . 5 P Schottky layers. In addition, the best wet etching selectivity between GaAs and (Al 0 . 3 Ga 0 . 7 ) 0 . 5 In 0 . 5 P was obtained for large area power transistors. The developed 0.5 μm long and 1.2 mm wide gate FETs exhibited a V t h of +0.1 V and a maximum drain current (I d m a x ) of 385 mA/mm. The maximum output power at 1.9 GHz was 95 mW/mm with a linear power gain of 22 dB and a power-added efficiency of 60%. These characteristics demonstrate this novel E-mode pHEMTs have great potential for use in microwave power device applications.

High uniformity enhancement- and depletion-mode InGaP/InGaAs pHEMTs using a selective succinic acid gate recess process

High uniformity enhancement-mode (E-mode) and depletion-mode (D-mode) InGaP/InGaAs pseudomorphic high electron mobility transistors (pHEMTs) have been developed on 6 inch GaAs substrate using a selective succinic acid gate recess process. The 0.5 µm long gate fingers of E-mode and D-mode pHEMTs are deposited simultaneously in this process simplification. The InGaP/InGaAs E-mode pHEMT exhibits a maximum drain-to-source current (Ids) of 460 mA mm−1, and a maximum transconductance (gm) of 430 mS mm−1. At 5.2 GHz operation, 216 mW mm−1 power density, 40% power-added efficiency and a 0.81 dB minimum noise figure (NFmin) are also achieved for the E-mode device. In this study, D-mode pHEMTs are applied for a switch monolithic microwave integrated circuit which provides an insertion loss of −1.8 dB and isolation of −9.2 dB under 28 dBm input power (Pin) and 5.5 GHz operation. From these measured results, this uniform E/D-mode InGaP/InGaAs pHEMT technology exhibits a high potential for WLAN applications.

High breakdown voltage (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P/InGaAs quasi-enhancement-mode pHEMT with field-plate technology

A high breakdown voltage and a high turn-on voltage (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P/InGaAs quasi-enhancement-mode (E-mode) pseudomorphic HEMT (pHEMTs) with field-plate (FP) process is reported for the first time. Between gate and drain terminal, the transistor has a FP metal of 1 μm, which is connected to a source terminal. The fabricated 0.5×150 μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> device can be operated with gate voltage up to 1.6 V owing to its high Schottky turn-on voltage (V/sub ON/=0.85 V), which corresponds to a high drain-to-source current (I/sub ds/) of 420 mA/mm when drain-to-source voltage (V/sub ds/) is 3.5 V. By adopting the FP technology and large barrier height (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P layer design, the device achieved a high breakdown voltage of -47 V. The measured maximum transconductance, current gain cutoff frequency and maximum oscillation frequency are 370 mS/mm, 22 GHz , and 85 GHz, respectively. Under 5.2-GHz operation, a 15.2 dBm (220 mW/mm) and a 17.8 dBm (405 mW/mm) saturated output power can be achieved when drain voltage are 3.5 and 20 V. These characteristics demonstrate that the field-plated (Al/sub 0.3/Ga/sub 0.7/)/sub 0.5/In/sub 0.5/P E-mode pHEMTs have great potential for microwave power device applications.

High-performance enhancement-mode pseudomorphic InGaP/InGaAs/GaAs HEMT structures by gas source molecular beam epitaxy

Abstract Enhancement-mode (E-mode) operation In 0.49 Ga 0.51 P/In 0.2 Ga 0.8 As/GaAs PHEMTs were designed for high performance and were successfully grown by gas source molecular beam epitaxy (GSMBE). An optimized GSMBE growth process based on the memory effect studied has been applied to precisely control the InGaP/InGaAs and InGaP/GaAs interface quality and composition. The lattice mismatch of 10 −4 and composition uniformity of better than ±0.2% for 3″ diameter InGaP/GaAs layers were obtained. E-mode operation InGaP/InGaAs PHEMTs and related low-noise amplifier (LNA) circuits were obtained. The E-mode PHEMT had a threshold voltage near 0 V and the LNA can operate under a single-voltage supply of 1.5–3.0 V and at 2.5 GHz with a gain of over 20 dB and a noise figure ( N f ) of 3.43 dB.

Enhanced power performance of enhancement-mode Al/sub 0.5/Ga/sub 0.5/As/In/sub 0.15/Ga/sub 0.85/As pHEMTs using a low-k BCB passivation

Surface passivation technology plays an important role, especially in E-mode pHEMTs applications, and a new passivation technology has been proposed in this study. This novel benzocyclobutene (BCB) passivation layer takes advantage of the low dielectric permittivity (2.7) and a low loss tangent (0.0008). In this letter, we not only suppress the gate-to-drain leakage current but also improve the device power performance under a high input power swing by using a BCB passivation layer. The passivated 1.0 /spl mu/m-long gate pHEMTs exhibit a better off-state performance than the unpassivated ones. The maximum output power under a 2.4-GHz operation is 118 mW/mm, with a linear power gain of 11.1 dB and a power-added efficiency is 60%.

E-pHEMT complements HBT - may challenge below 3 V

A topic of much debate in gallium arsenide IC manufacturing currently is the challenge to HBTs from new Enhancement-mode pHEMT transistors for power amplifiers in low-volt-age, portable wireless handsets. This was reflected in panel session at 22 nd IEEE GaAs IC Symposium in Seatlle last November (”E-mode pHEMTs are killing HBTs“) and, more recently, by the first E-pHEMT product launches by leading GaAs RFIC manufacturers.