# Geometry Effect on SiGe Heterojunction Bipolar Transistor Unit Cell for 1 W High-Efficiency RF Power Amplifier Applications

## 抄録

The effect of geometry on the RF power performance of silicon–germanium heterojunction bipolar transistor (SiGe HBT) unit cells is investigated using various emitter finger spacing ($S$). Two unit cells, namely, HBT-1 and HBT-2 with the same emitter area of $8\times 0.6\times 10$ μm3 but with different $S$ values are thoroughly discussed. The $S$ values of HBT-1 and an HBT-2 are 2 and 5 μm, respectively. The obtained measurements, including DC characteristics and small- and large-signal performance characteristics of high-breakdown SiGe HBT unit cells, are presented. The HBT-1 in class-AB operations at 2.4 GHz achieves an output 1 dB compression point ($\mathrm{OP}_{\text{1dB}}$) of 16.0 dBm, a maximum output power of 17.4 dBm, and a peak-power added efficiency (PAE) of 59.1%. Under the same testing conditions, HBT-2 achieves an $\mathrm{OP}_{\text{1dB}}$ of 19.6 dBm, a maximum output power of 20.6 dBm, and a PAE of 64.5%. HBT-2 yields significant improvements in all power performance parameters compared with HBT-1, such as 3.6 dB in an $\mathrm{OP}_{\text{1dB}}$, a maximum output power of 3.2 dB, a PAE of 5.4%, and an improvement in the power performance figure of merit (FOM) of approximately 50%, which is attributed to the fact that HBT-2 has a lower thermal effect than HBT-1. The thermal effect affects both DC and output power characteristics. A 1 W power device fabricated by combining eight HBT-2 unit cells achieves a power gain of 14.5 dB and a maximum PAE ($\mathit{PAE}_{\text{max}}$) of 75% in a class-AB operation at 2.4 GHz. The power density is calculated to be up to 2.6 mW/μm2. These results demonstrate that SiGe HBT technology has great potential for high-power amplifier applications.

## 収録刊行物

• Japanese journal of applied physics. Pt. 1, Regular papers & short notes

Japanese journal of applied physics. Pt. 1, Regular papers & short notes 46(3A), 917-925, 2007-03-15

Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physics

## 各種コード

• NII論文ID(NAID)
10018866601
• NII書誌ID(NCID)
AA10457675
• 本文言語コード
EN
• 資料種別
ART
• 雑誌種別
大学紀要
• ISSN
0021-4922
• NDL 記事登録ID
8687883
• NDL 雑誌分類
ZM35(科学技術--物理学)
• NDL 請求記号
Z53-A375
• データ提供元
CJP書誌  NDL  JSAP

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