Barry Lin

High efficiency 28V class AB InGaP/GaAs HBT MMIC amplifier with integrated bias circuit

InGaP/GaAs HBTs have demonstrated excellent lifetime and linearity performance for 3 to 10 V operation. This is very attractive for infrastructure applications. However, the low voltage is a drawback in this application where 28 V is a common voltage used. In this effort, a high voltage InGaP/GaAs HBT is developed for 28 V operation. The safe operation area is carefully designed, allowing the device to function in class A mode. A thermal resistance of 30/spl deg/C/W for a 1 W HBT design is measured using the V/sub be/ method. 4 W CW power with 71% efficiency is measured from this 1 W design, with a junction temperature rise of 49/spl deg/C. The integrated temperature compensated bias circuit provides <9% quiescent current change over base plate temperatures from -40 to +85/spl deg/C. Two tone and CDMA2000 linearity is also characterized. Initial WLR (wafer level reliability) results indicate that it has a similar lifetime to the standard InGaP/GaAs HBT.

Linearity improvement of multi-Watts 24-28 V InGaP/GaAs HBT by low frequency low source impedance matching

InGaP/GaAs HBT running at 24-28 V operation voltage has demonstrated over 20 W output power in the standard MMIC format with efficiency over 60%. On-chip power combining of multiple HBT building-blocks successfully delivered the power transistor with multi-tens watt output power without any undesired spur. Two-tone linearity and other modulation signal were used to characterize the linearity of the HBT power transistor. By properly matching the HBT at the RF frequency, as well as the low frequency source impedance, linearity is clearly improved. WCDMA signal with ACLR1=-45 dBc is achieved with only 8 dB backoff, as compared with the WCDMA test method 1 of 9.8 dB peak-to-average ratio; the efficiency reaches 20%. This effort clearly demonstrated the potential of InGaP/GaAs HBT in the high power, high voltage operation.

Advanced heterostructure transistor technologies for wireless communications

Abstract Wireless communication has enjoyed tremendous growth in the last five years. Most of the market is below the 3 GHz. Recently, millimeter wave frequency band was also opened up to commercial applications, such as the Local Multipoint Distribution System. The rapid growth of the market demands cost effective RF circuitry with ever better performance. Thus, the heterostructure transistors are pursued to meeting the market needs. This article will first analyze the technical demand on RF transistor circuitry for wireless application. Existing and emerging transistor technologies will be discussed for its strength. A general comparison will be made.

High linearity 40 watt, 28V InGaP/GaAs HBT

This paper reports on a 40W high linearity InGaP/ GaAs 28V HBT. It uses a high breakdown voltage, high ruggedness HBT process developed by WJ. The device employs a dynamic bias circuit to improve ACLR under WCDMA modulation conditions. The P-1dB of the device reaches 46dBm (40W), with a gain around 14.5dB. With WCDMA one carrier modulation (PAR=8.5dBc), the device achieves an ACLR of −50dBC and an efficiency of 19.5% at an output power of 37.5dBm (5.6W) at 920–960MHz frequency band. Without the help of a DPD, the performance of this device will make it an excellent choice for base station and repeater applications.

1.5–2.7 GHz ultra low noise bypass LNA

Bypass low-noise amplifier (LNA) can be used in the base station receiver to improve the dynamic range. It is difficult to achieve both ultra low noise at LNA mode and maintain good linearity at bypass mode simultaneously. In this work, we present the best performance bypass LNA with 0.5 dB of noise figure (NF), 20 dB of gain at 1.95 GHz and high OIP3 of 35 dBm for both LNA and bypass mode. Fabricated in 0.25um GaAs E/D pHEMT process, the LNA is based on enhancement mode pHEMT cascode topology and the switches are designed with the depletion mode pHEMT.

A scalable high power nonlinear HBT model for a 28V HVHBT

A scalable nonlinear HBT model for a Building Block (1BB) of 28V InGaP/GaAs HBT is presented. It is based on the AgilentHBT (AHBT) model. The building block consists of 32 finger HBTs, an input pre-matching circuit and a transistor used as an emitter follower in the related bias circuit. The P1dB of 1BB is 32.5dBm. The model can account not only for DC, thermal, junction capacitances, S-parameters but also RF power, gain, IM3, operation current and collector efficiency. A good match between simulation and measurement has been achieved. By using a multiplicity parameter the model can accurately predict the DC and nonlinear RF performance of two Building Blocks (64 fingers, P1dB of 35.7dBm) and four Building Blocks (128 fingers, P1dB of 38.2dBm).

Ultra low-noise highly linear integrated 1.5 to 2.7 GHz LNA

This paper presents a wideband, fully integrated, low-noise amplifier with a noise figure of less than 0.5 dB. The device is fabricated in a 0.35 μm GaAs enhancement-mode pHEMT process because of its positive threshold voltage and superior noise performance. The amplifier is housed in a low-cost 2×2 mm2 8-pin QFN plastic package with internal gate biasing and input and output matching. To our knowledge, this work achieved the best result of reported combination of low noise figure, OIP3 (40 dBm), and Linearity Figure of Merit (LFOM) of 15dB at a frequency range of 1.5-2.7GHz for sub-0.5 dB NF LNA, and integrated power-down function for system control.

An accurate packaged model for HVHBT 120W power amplifiers and its application to 250W Doherty amplifiers

An accurate yet straightforward modeling approach is reported to develop a packaged model for InGaP/GaAs HVHBT 120W power amplifiers (PA) at 2140MHz. The model consists of an accurate HBT model, models for internal pre-match circuits and models for coupled bond-wire arrays. The HBT model is scaled up from an AHBT (Agilent HBT) model for a unit cell transistor. The models for the internal pre-match circuits are lumped-element equivalent circuit models derived from the EM simulated S-parameters. For high power amplifiers, the coupling between the bond-wires must be accounted for. In this work, the coupling between the bond-wires is determined up to the 4th next bond-wires. The model of 120W PA can precisely simulate small signal S-parameters as well as large signal performances of harmonic load-pull power sweep, such as output power, P1dB, G1dB, efficiency and operation current. A very good agreement between simulation and measurement has been achieved. The model is then applied to simulate a 250W symmetric Doherty amplifier with an efficiency above 70%. The results of simulation agrees well with the measurement. The difference in efficiency between simulation and measurement is only 1.6%.