Thermal Noise Measurement May Boost Wireless Device Battery Life

It usually happens at the worst moment: You lose your link to the outside world when your wireless device's battery dies. Now the National Institute of Standards and Technology is developing heartier batteries by measuring energy-sapping thermal noise on transistors.

The motion of electrons produces thermal noise in electronic circuits. At times these noises are barely discernible, making them difficult to measure. NIST researchers working with IBM and RF Micro Devices have developed a way to measure faint thermal noise before wireless devices' transistors are cut from silicon wafers. The method may improve a device's signal range and data rate, meaning longer life for its battery.

Low background noise usually means better performance in electronics, such as longer ranges or higher information-carrying capacity. But circuit designers can't optimize performance when thermal noise is too low to measure. The NIST research focuses on improving complementary metal oxide semiconductor, or CMOS, transistors used in integrated circuits for wireless devices. Noise levels for CMOS transistors have been too low to measure accurately in much of their signal frequency range, so they've been a poor match for use in wireless transmission systems.

NIST--a federal agency that promotes standards for U.S. industry--says this measurement method is the first to be tied to standards for thermal noise power.