CMOS RF switches avoid potential GaAs pains
By Bill Schweber -- EDN, October 28, 2004
The RF-antenna switch of a cell phone is critical to performance, and it must meet severely conflicted signal requirements. Providing the first meeting of CMOS-process technology with a handset antenna, Peregrine Semiconductor says that its two RF antenna switches, which it built with its sapphire-based SOI (silicon-on-insulator)-process technology, enable the first direct CMOS-to-antenna interconnection. According to President and Chief Executive Officer James S Cable, the company’s PE4261 SP4T switch for dual-band GSM designs and the PE4263 SP6T quad-band GSM switch show that this proprietary process technology can provide performance equivalent to GaAs (gallium-arsenide) but with the numerous and well-known benefits of CMOS—albeit just for the 0- to 3-GHz range (Picture).
Basic performance specifications of the two parts are similar. The 50Ω PE4261 SP4T IC integrates the two-line control-logic decoder and driver, reducing parts count and footprint. Insertion loss is 0.55 dB at 900 MHz and rises to only 0.65 dB at 1.9 GHz. Similarly, isolation is 45 and 40 dB at 900 and 1.9 GHz, respectively. Maximum switching time is 3 μsec, and power handling is 41 dBm (P1 dB). The 2.6V IC, priced at 52 cents (10,000), does not need the approximately 10 external blocking capacitors that you would include if you used a PHEMT (positive high-electron-mobility transistor)-based switch. ESD tolerance, a practical but vital issue in assembly, is 1500V using the human-body-model standard. The similar quad-band PE4263, also a 2.6V, 50Ω IC, sells for 60 cents.
Peregrine Semiconductor Corp, 1-858-455-0660, www.psemi.com.
