Hsiang-Ming Huang

A fully matched 8W X-band PHEMT MMIC high power amplifier

A X-band 8-watt AlGaAs/InGaAs/GaAs PHEMT MMIC power amplifier for the active phase radar applications is demonstrated. This amplifier is designed to fully match 50 ohm input and output impedance. With 8 volts and 850 mA DC bias condition, 17.5 dB small-signal gain, 39.3 dBm (8.5 watt) 2-dB gain compression power with 33.7% power-added efficiency and 40 dBm (10 watt) saturation power from 9.3 to 10.4 GHz can be achieved.

High reliability in low noise InGaP gated PHEMTs

This work presents a study on the high reliability of noise characteristics of InGaP low noise PHEMTs, which was demonstrated through DC and thermal stress. The devices that we used were In/sub 0.49/Ga/sub 0.51/P/In/sub 0.15/Ga/sub 0.85/ As/GaAs low noise pseudomorphic high electron mobility transistors (PHEMTs) with the gate dimensions of 0.25 /spl times/ 160 /spl mu/m/sup 2/. The DC-stress conditions are 1) V/sub DS/ = 6V, V/sub GS/ = 0V and 2) I/sub G/ = -8 mA (50mA/mm). The ranging of thermal-stress is from 100/spl deg/C to 250/spl deg/C. The noise characteristics were measured at 12 GHz and DC bias condition is V/sub DS/ = 2V, I/sub DS/ = 10 mA. The key noise-effect parameters of devices are the deep-trap behaviour in device, source/gate resistances, gate to source capacitance and intrinsic transconductance. We showed the very small variation of minimum noise figure, NF/sub min/ and associated power gain, G/sub a/ after DC and thermal stress by explaining the variation of these key parameters to demonstrate the high reliability in InGaP low noise PHEMTs.

Super low noise InGaP gated PHEMT

Very high performance InGaP/InGaAs/GaAs PHEMT is demonstrated. The fabricated InGaP gated PHEMT device with 0.25/spl times/160 /spl mu/m/sup 2/ of gate dimension shows a 304 mA/mm of saturation drain current at V/sub Gs/=0V, V/sub DS/=2 V and a 320 mS/mm of extrinsic transconductance. Noise figure at 12 GHz is measured to be 0.46 dB with a 13 dB associated gain. With such a high gain and low noise, the drain-to-gate breakdown can be as high as 10 V. Standard deviation in the threshold voltage of 22 mV across a 4-inch wafer can be achieved using a highly selective wet recess etching process.

A Self-bias Ku-band 1-Watt PHEMT Power Amplifier MMIC With A Compact Source Capacitor

In this paper, the design of a self-bias 1.8 mm AlGaAs/InGaAs/GaAs PHEMT with a compact source capacitor for operation in Ku-band frequency is described. Based on the proposed device, a self-bias Ku-band 1-W two-stage power amplifier MMIC is also demonstrated. Under single bias condition of 8 V and 630 mA, the self-bias MMIC possesses 14.2 dB small-signal gain, 30.2 dBm output power at 1-dB gain compression point with 19.2% power added efficiency and 31.3 dBm saturated output power with 22.5% power added efficiency at 14 GHz. With the performance comparable to the dual-bias MMIC counterpart, the proposed self-bias MMIC is more attractive to system designers on VSAT applications.

A Single-bias 2W PHEMT MMIC by Gate Zero-Bias Technique for C Band Applications

A single supply, fully matched high linearity 2W power amplifier utilizing the gate zero-bias power PHEMT technology is developed for 5.8GHz WLAN applications. At Vgs= 0 V, Vds= 5 V, the power amplifier with 33dBm of peak P1dB, 25% of PAE, 12.8dB small-signal gain can be seen. Moreover, high-linearity with 43dBm third-order intercept point at a single carrier output power level of 23dBm is also achieved.

A Gate Zero-Bias 2W PHEMT Power Amplifier Operating at 3.5 GHz

A single supply 2W MMIC power amplifier, operating between 3.3GHz and 3.8GHz by implementing AlGaAs/InGaAs/GaAs PHEMT for the applications of WiMax, is demonstrated. Using the gate zero-bias configuration, i.e., VGS=0 and IDSS, one can use only one single bias instead of dual bias in the depletion mode PHEMTs. This two-stage amplifier is designed by using a zero gate bias configuration i.e., VGS=0 and at saturated drain current IDSS, for class A power amplifier operation. The two-stage MMIC amplifier possesses the characteristics of 25.9dB small-signal gain and 34.0dBm 1-dB gain compression power. Moreover, with a single carrier output power level of 2ldBm, very high linearity with a 47dBm third-order intercept point operating at 3.5GHz is also achieved.

Comparison of InGaP-with AlGaAs-gated Low Noise PHEMTs by Current-Dependent Hot-Electron Stresses

A newly proposed method, called the current-dependent hot-electron stresses, is used to study InGaP-gated and AlGaAs-gated low noise PHEMT devices with different drain currents at high drain voltage. The impact ionization between gate and drain is major mechanism affecting devices during hot-electron stressing, which are excited by the high gate-to-drain electric field. However, the measure of the effects of impact ionization related to the drain current, during the hot-electron stressing, is less discussed in the published literatures. In this work, the designed hot-electron stressed conditions, which are related to the different drain currents are used to demonstrate the influence of drain currents in hot-electron stresses and, furthermore, to estimate and compare InGaP-gated with AlGaAs-gated PHEMTs.

High linearity power amplifier for PHS base station using a 50 mm AlGaAs/InGaAs/GaAs PHEMT

A high linearity, high efficiency 1.9 GHz power amplifier sub-system using a 50 mm AIGaAs/InGaAs/GaAs PHEMT for PHS 500 mW base station is demonstrated. Under 10 V and 3.8 A bias condition, the output stage amplifier has achieved 12.5 dB small-signal gain, 43.7 dBm PldB with 43% PAE and 44 dBm saturated output power with 41% PAE. For the amplifier sub-system, the ACPR at 600 KHz and 900 KHz offset from 1.906 GHz when operating at 38.5 dBm output power with /spl Pi//4-DQPSK signal are better than 75 dBc and 79 dBc, respectively.

L-band, high efficiency 25 watt power amplifier using PHEMT for base station system

In this paper, a 1.9 GHz watt high power amplifier using AlGaAs/InGaAs/GaAs PHEMT device for PHS base station applications is demonstrated. This amplifier utilizes a pre-matched FET which is composed of only a single 50 mm FET device and a MIS capacitor in a CuW flange package with other matching circuits on the FR4 PCB. Under 10 Volts and a 4 A dc bias condition, the amplifier has achieved 12.5 dB small-signal gain, 43.7 dBm 1 dB gain compression power with 43% power-added efficiency (PAE) and 44 dBm saturated output power with 41% PAR. In addition, high linearity with 53 dBm third-order intercept point is achieved. The ACP at 600 KHz offset from 1.906 GHz when operating at 39 dBm output power with /spl pi//4-DQPSK signal is better than 71 dBc.

Hot electron effects on AlGaAs/InGaAs/GaAs PHEMT's under accelerated DC stresses and comparison with InGaP PHEMT's

The influence of the hot electron accelerated stress on DC characteristics of AIGaAsfInGaAsfGaAs pseudomorphic high electron mobility transistors (PIIEMTs) is found to be related to the Schottky characteristics. The studies of reverse Schottky characteristics before and after stress are presented and found to be related to the following two major mechanisms: ( I ) the widening of the depletion under the gate atter stress; (2) the influence of the camers trapping under the gate after stress, which is mainly due to DX-centers. A new model based on the image force of Schottky barrier on hot electrons effects on leakage gate current is proposed. Both AlGaAs and InGaP PHEMTs with the extreme small variation of miniinutn noise figure and associated power gain measured at 12 GHz under hot electron accelerated stress will be investigated. Comparing the noise perfonnance of AIGaAs PHEMTs wilh InGaP PHEMTs, the higher reliability in ItiGaP low noise PHEMTs will be demonstrated.