# Ultra-small Form-Factor Helix on Pad-Type Stage-Bypass WCDMA Tx Power Amplifier Using a Chip-Stacking Technique and a Multilayer Substrate

• Yoo, Chang-Hyun (School of Electrical Engineering and Computer Science, Hanyang University) ;
• Kim, Jung-Hyun (School of Electrical Engineering and Computer Science, Hanyang University)
• Accepted : 2010.01.22
• Published : 2010.04.30

#### Abstract

A fully integrated small form-factor HBT power amplifier (PA) was developed for UMTS Tx applications. For practical use, the PA was implemented with a well configured bottom dimension, and a CMOS control IC was added to enable/disable the HBT PA. By using helix-on-pad integrated passive device output matching, a chip-stacking technique in the assembly of the CMOS IC, and embedding of the bulky inductive lines in a multilayer substrate, the module size was greatly reduced to 2 mm ${\times}$ 2.2 mm. A stage-bypass technique was used to enhance the efficiency of the PA. The PA showed a low idle current of about 20 mA and a PAE of about15% at an output power of 16 dBm, while showing good linearity over the entire operating power range.

#### Acknowledgement

Supported by : Hanyang University

#### References

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