In spacecraft applications there is a great need for robust analogue to digital converters (ADC) that can withstand the harsh space environment. Commercially available ADCs cannot operate in the space environment due to radiation effects. In this paper we present an ADC that has been developed for the NASA TRIO smart sensor system on a chip (SoC), a versatile low power device specifically designed for spacecraft data acquisition and telemetry of several types of sensors such as temperature, voltage/current transducers, radFETs, etc. It is required for the ADC to operate in excess of 300 Krad total ionizing dose and to be robust to single event upsets. The successive approximation topology was chosen and it was enhanced with a special auto-zeroing technique to compensate for possible lifetime offset errors. Due to the comparator design, a rail-to-rail input capability is achieved, a feature very useful in some type of Vdd ratio metric sensors. It has 10-bit resolution for a reference in the range 0.1 to Vdd + 1 V, and for power supply in the range 2.5 to 5.5 V; the positive reference terminal Vref+ is settable up to Vdd + 0.5 V and the negative voltage terminal is settable down to GND-0.5 V. The power dissipation is less than 2 mW at 50 Ksamlles/sec. The TRIO chip is used in several NASA spacecraft including CONTOUR, STEREO, MESSENGER, EUROPA, PLUTO, etc.

An 11-bit time-to-digital converter (TDC) with high time resolution implemented in CMOS VLSI is presented. The TDC operates with a wide and clock-adjustable resolution of LSB = 50 ps to 1 ns, and with good power supply, temperature, and environmental effects compensation. The dead time of the measurement is as low as 0.5 /spl mu/s and the event rate can be as high as 1 MEvents/s. The power dissipation is a function of event rate and clock frequency; the TDC dissipates <10 mW at an event rate of 100 kEvents/s and LSB=100 ps. The TDC was incorporated in a complete time-of-flight (TOF) system on a chip that in addition included front-end analog signal processing. The TOF chip is already flying onboard the HENA (High Energy Neutral Atoms) instrument of the IMAGE NASA mission, launched in 2000, and is part of many other instruments such as particles, X-ray, and the laser altimeter of the Messenger spacecraft.

A CMOS time to digital converter (TDC) chip with wide dynamic range, high resolution and ability to accept input asynchronous to the time reference (external clock) is discussed. The system presents low power dissipation, small processing time and an adjustable range and measurement step. The chip is intended for laser altimetry and particle detection and recognition instruments in scientific space missions.

This paper presents several design and testing aspects of the TRIO smart sensor data acquisition chip, developed by JHU/APL for NASA spacecraft applications. TRIO includes a 10-bit self corrected ADC, 16/32 analog inputs, a front end multiplexer with selectable acquisition time, a current source, a memory unit, a serial and a parallel bus, and a control logic. So far TRIO is used in many missions including Contour, Messenger, Stereo, Pluto and the generic JPL X2000 spacecraft bus.

Many remote sensing instruments include the detection of photon/particle events, position decoding and time-of-hit measurement. Microchannel plates (MCPs) are widely used to detect photons and particles for position sensing and relative time of impact in imaging and time-of-flight (TOF) spectrometers. Two dimensional delay lines are used for fast and accurate readout of MCPs. Instruments that use these techniques are Neutral Atom Imagers and Particle Spectrometers to study planetary magnetospheres; photon counting detectors for spectrographic imaging in the far-UV and extreme-UV to study the earth's aurora and airglow; laser range finders. In all these there is a requirement of accurate and/or fast time interval measurement. An advance TOF system-on-a-chip has been developed that includes the complete signal processing electronics for MCP readout: two channels (start- stop) of amplifiers and constant fraction discriminators (CFDs), an 11-bit Time to Digital Converter (TDC), and control/readout logic. The TOF chip is capable for a time resolution of <50ps including time walk and time jitter, the dead time is as low as 0.5us; the power dissipation is a function of counting rate and time resolution-for resolution of similar to100ps the power is <20mW at rates <100K/sec and <50mW at rates <1M/sec. The TOF chip flies on the NASA/IMAGE spacecraft launched in 2000 and is part of many other science instruments such as particles and fields, and laser altimeter on MESSENGER.

A CMOS time-of-flight (TOF) system-on-a-chip (SoC) for precise time-interval measurement with low power and high rate has been developed. Microchannel plate electron multipliers or photomultiplier tubes (PMTS) typically produce the start-stop delta-Ts of radiation events to be processed. The TOF chip includes two constant fraction discriminators (CFDs) and a time-to-digital converter (TDC). The CFDs interface to start and stop anodes through two simple preamplifiers and perform the signal processing for time walk compensation. The TDC digitizes the time difference with reference to an off-chip precise oscillator. The design is full custom in both the analog and the digital sections. A first version of the TOF chip developed in a 0.8-mum CMOS process achieved CFD time walk of similar to350 ps for an input amplitude dynamic range of 40 db and a combined CFD+TDC time jitter of similar to180 ps. The total power dissipation was similar to20 mW at an event rate of 100 K/s and similar to30 mW at a rate of 1 Meg/s. This chip is part of the high-energy neutral atom instrument onboard the NASA/IMAGE spacecraft launched in March 2000. It is selected for many other instruments, including the particle sensor, the fast plasma sensor, and the laser altimeter of Messenger for the Mercury exploration to be launched in 2004.

A time-of-flight (TOF) system-on-a-chip (SoC) for precise time interval measurement at low power and high rate has been developed. A micro-channel plate (MCP) electron multiplier typically produces the start and stop of a radiation event to be processed. The TOF chip includes two Constant Fraction Discriminators (CFDs) and a Time to Digital Converter (TDC). The CFDs interface to start and stop anodes through two simple preamplifiers and perform the signal conditioning for time walk compensation. The TDC portion digitizes the time difference with reference to an external precise oscillator. A first version of the TOF chip developed in a 0.8 u CMOS process achieved /spl sim/350 ps total time resolution, including time walk and time jitter, with /spl sim/20 mW power consumption at a rate of /spl sim/100 K events/sec and /spl sim/30 mW @ 1Mevents/sec. This chip is part of the HENA instrument of the NASA/IMAGE mission launched in March 2000 and is baselined for many other missions including the Energetic Particle Sensor (EPS) of Messenger etc.

In spacecraft applications there is a great need for robust analogue to digital converters (ADC) that can withstand the harsh space environment. Commercially available ADCs can not operate in space due to radiation effects. We present an ADC that has been developed for the NASA TRIO smart sensor system on a chip (SoC), a versatile low power device specifically designed for spacecraft data acquisition and telemetry of several sensors such as temperature, voltage/current transducers, radFETs, etc. A key element of the TRIO chip is the ADC, which is required to operate in excess of 500Krad ionising dose and to be robust to single event upsets. The topology chosen is simple with a special auto-zeroing technique to compensate for offset errors. The ADC has 10-bit resolution for a reference in the range 0.1V to Vdd + 1V, and for power supply in the range 2.5 V to 5.5 V. The power dissipation is ∼2mW at 40Ksamlles/sec. The TRIO chip is used in several spacecraft including Contour, Messenger, Europa, Pluto, etc.