Packing more RF functions on a single die at low cost and without compromising performance is not a trivial task. But that is what new-generation cellular and mobile phones are demanding. Toward that goal, RFIC supplier Anadigics has succeeded in combining heterojunction bipolar transistors (HBTs) with pseudomorphic high-electron mobility transistors (pHEMTs) on a single indium gallium phosphide (InGaP) gallium arsenide (GaAs) die. The result is the ability to integrate both power amplifiers (PAs) and RF switches on the same chip. Earlier such functions were built on separate dies.

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According to Aditya Gupta, Anadigics’ vice president of technology, “In this integrated HBT/pHEMT process, we have achieved optimal performances on both types of devices to minimize the cost. It allows you to go from multiple die solution to a single die solution, thereby offering huge cost savings to the designers," noted Gupta.

Gupta added that the complexity is only marginal, but the yield is good and is comparable to standalone HBT process.

Labeled InGaPPlus, this process was under development for two years and was demonstrated in early 2003 with production capability achieved toward the end of 2003. Recently, it resulted in high-efficiency-at-low-power (HELP) line of WCDMA PAs with almost 50% reduction in power consumption as well as significant improvement in power-added efficiency at mid-range power. By comparing data sheets of HELP model AWT6138 to an older-model AWT6135 built on standard HBT process, it is seen that HELP PA provides 22% PAE at +16 dBm as compared to 9% for AWT6135. Also, the quiescent or idle current for HELP is substantially lower, which dramatically improves talk time.

The company continues to refine the process and improve the transistor behavior for new PA designs, enabling the company to build high-performance PAs at lower voltages. Meanwhile, with new refinements, it is also looking at extending the technology to functions beyond PAs. However, further details were unavailable at the time of print.