SENSING CIRCUITS: Nanopower MOSFETs promise long-life sensors

Sunnyvale, Calif. — Right on the heels of its zero-threshold MOSFETs, Advanced Linear Devices (ALD) is bringing out a line of Nanopower MOSFETs, devices that can build circuits that operate on as little as 100 millivolts.

The devices, based on ALD's floating-gate charge-programming technology, can pave the way for a new generation of electronic sensor-amplifier circuits that run forever on batteries or ambient power, the company said. Ambient-power generators include solar cells, capacitors and microminiature generators. In addition to sensor networks, Nanopower devices will support medical monitoring applications.

The parts are based on enhancement-mode MOSFET arrays with extraordinarily low turn-on characteristics. As with ALD's other electrically programmable arrays, the threshold is controlled by a floating-gate charge that is set at the factory. Gate thresholds for the new devices are 200 mV, with a tolerance of 20 mV and an offset of 10 mV.

This family will play an important role in such circuits as current sources, current mirrors, discrete differential amplifiers and analog multiplexers, said Bob Chao, ALD's president and chief technical officer. With operating currents of less than 1 microamp (0.1 nA quiescent), the ultralow-turn-on voltages offer designers the ability to construct circuits whose power consumption is measured in nanowatts.

The first MOSFETs in the family are quad/dual n-channel matched pairs, differentiated by their thresholds. The ALD110802 and ALD110902 have a gate threshold voltage of 0.2 V (0.02 V) at 1 µA. The ALD110808 and ALD110908 turn on with 0.8 V (0.02 V) at 1µA, while the ALD110814 and ALD110814 turn on with 1.4 V (0.04 V). Available in PDIP and SOIC packages, the MOSFETs are now available from stock. Pricing starts at 67 cents each in quantities of 100.