A 4- $\mu\hbox {W}$ CMOS Front End for Particle Detection Applications

A complete low-power front end for particle detection applications is presented. The front end integrates a charge-sensitive amplifier with a novel adaptive biasing scheme that allows the dc bias currents to be scaled below conventional limits. A downstream peak detector circuit captures the peak value for each detection event, which is then fed to an integrated analog-to-digital converter (ADC). The event-driven ADC is shut off in between detection events to further reduce power consumption. The circuit has been fabricated using a 0.18- μm CMOS technology, with a power consumption ranging between 4 and 20 μW, depending on the particle detection rate. This low-power operation facilitates the development of compact long-life battery-powered remote particle sensors.