IBM combines transistors to speed wireless chips

IBM Corp. has developed a technique for building two different types of silicon transistors atop a single wafer that is expected to boost the performance of communications devices, the company announced Tuesday. The overwhelming majority of transistors built since the mid-1980s are known as CMOS (complementary metal-oxide semiconductor) transistors. But in the earlier part of the history of computing, most chips used what are known as bipolar transistors, said Ghavam Shahidi, director of silicon science for IBM Research.

Bipolar transistors are very good at amplifying low noises, or picking up quiet signals in loud environments, Shahidi said. For that reason, they are still used in some communications chips, although in small quantities due to their rabid power consumption and high manufacturing cost, he said.