B.R. Blaes

On-chip p-MOSFET dosimetry (CMOS ICs)

On-chip p-FETs were developed to monitor the radiation dose of n-well CMOS ICs by monitoring threshold voltage shifts due to radiation-induced oxide and interface charge. The design employs closed-geometry FETs and a zero-biased n-well to eliminate leakage currents. The FETs are operated using a constant current chosen to greatly reduce the FETs temperature sensitivity. The dose sensitivity of these p-FETs is about -2.6 mV/krad(Si) and the off-chip instrumentation resolves about 440 rad(Si)/b. When operated with a current at the temperature-independent point, it was discovered that the preirradiation output voltage is about -1.5 V, which depends only on design-independent silicon material parameters. The temperature sensitivity is less than 63 mu V/ degrees C over a 70 degrees C temperature range centered about the temperature-insensitive point. >

Integrated environmental monitoring system for spacecraft

This paper describes an integrated space environmental monitoring system for geosynchronous satellites. The system provides measurements of surface charging, internal charging, and total dose radiation from the space environment. It is installed on seven of Martin Mariettas commercial communications spacecraft, which are scheduled for launch in the near future. There are two components: an internal charge monitor, and a surface charge detector. Total weight is less than one pound; power consumption, about 0.5 watt. Charging flux information from these detectors will permit evaluation of the effects of internal charging on electronic PC boards and will lead to the development of reliable, low-weight methods to detect on-orbit spacecraft charging events and to control charging and discharging.

CRRES microelectronic test chip orbital data. II

Data from a MOSFET matrix on two JPL (CIT Jet Propulsion Laboratory) CRRES (Combined Release and Radiation Effects Satellite) chips, each behind different amounts of shielding, are presented. Space damage factors are nearly identical to ground test values for pMOSFETs. The results from neighboring rows of MOSFETs show similar radiation degradation. The SRD (Space Radiation Dosimeter) is used to measure the total dose accumulated by the JPL chips. A parameter extraction algorithm that does not underestimate threshold voltage shifts is used. Temperature effects are removed from the MOSFET data. >

A monolithic RF microsystem in SOI CMOS for low-power operation in radiation-intense environments

A monolithic radio-frequency (RF) microsystem has been designed and fabricated in an advanced 0.25-micron SOI CMOS technology. The architecture is comprised of a compact digital core for local program execution and command handling; a 400-MHz RF transceiver for wireless program download and data transfer; and analog baseband circuitry which doubles as an embedded testability network. The IC is intended to support nanosatellite avionics and wireless remote sensing. The motivation of the work was to develop a team design methodology for producing integrated circuit (IC) intellectual property (IP) in the context of a specific application. Another intention is to investigate the suitability of an ultra-low-power digital technology for mixed-signal/RF circuit design. The design was a collaborative effort between UIC and JPL that demonstrates the potential for technology transfer between universities and federal laboratories.

Bench-level characterization of a CMOS standard-cell D-latch using alpha-particle sensitive test circuits

A methodology is described for predicting the SEU susceptibility of a standard-cell D-latch using an alpha-particle sensitive SRAM, SPICE critical charge simulation results, and alpha-particle interaction physics. Measurements were made on a 1.6- mu m n-well CMOS 4-kb test SRAM irradiated with an Am-241 alpha-particle source. A collection depth of 6.09 mu m was determined using these results and TRIM computer code. Using this collection depth and SPICE derived critical charge results on the latch design, an LET threshold of 34 MeV cm/sup 2//mg was predicted. Heavy ion tests were then performed on the latch and an LET threshold of 41 MeV cm/sup 2//mg was determined. >

A Hardware Platform for Tuning of MEMS Devices Using Closed-Loop Frequency Response

We report on the development of a hardware platform for integrated tuning and closed-loop operation of MEMS gyroscopes. The platform was developed and tested for the second generation JPL/Boeing post-resonator MEMS gyroscope. The control of this device is implemented through a digital design on a field programmable gate array (FPGA). A software interface allows the user to configure, calibrate, and tune the bias voltages on the microgyro. The interface easily transitions to an embedded solution that allows for the miniaturization of the system to a single chip

Proton-sensitive custom SRAM detector

Because of the recently discovered importance of protons to the upset of spaceborne electronics, a custom 4-kB SRAM (static random-access memory) chip was tested with protons. The SRAM was developed to determine the single-event-upset hardness of CMOS latches using alpha particle measurements, by adjusting an offset voltage that reduces the charge required to upset a cell. The authors describe a calibration procedure for the SRAM detector. Source spectra were acquired with this chip by measuring the number of upset cells versus offset voltage. The SPICE assisted calibration utilizing 56 fC/V and the proton data identified a 4.32-pm silicon equivalent overlayer and a 6.64+or-0.31 mu m effective charge collection depth for protons and a 6.33- mu m collection depth for alpha particles. These collection depths can be used to predict the SRAM detector response to proton-produced ionization in space. The SRAM collects all of the charge from silicon recoils produced by Rutherford scattering; this charge is collected from very deep in the SRAM substrate.<<ETX>>

Test SRAMs for characterizing alpha particle tracks in CMOS/bulk memories

Describes a methodology for using alpha particles to provide an independent measure of the cross section of an upset sensitive region in test SRAMs (static random-access memories). In addition, the thickness of over-layers and the alpha-particle collection depth were determined. These parameters are necessary in order to make precise estimates of the upset rates of memories due to cosmic-ray strikes. Measurements were made on 1.6- mu m n-well CMOS 4-kb test SRAMs irradiated with an Am-241 alpha-particle source.<<ETX>>

Clementine RRELAX SRAM particle spectrometer

The Clementine RRELAX radiation monitor chip consists of a p-FET total dose monitor and a 4-Kbit SRAM particle spectrometer. Eight of these chips were included in the RRELAX and used to detect the passage of the Clementine (S/C) and the innerstage adapter (ISA) through the Earths radiation belts and the 21-Feb 1994 solar flare. This is the first space flight for this 1.2-/spl mu/m rad-soft custom CMOS radiation monitor. This paper emphasizes results from the SRAM particle detector which showed that it (a) has a detection range of five orders of magnitude relative to the 21-Feb solar flare, (b) is not affected by electrons, and (c) detected microflares occurring with a 26.5 day period. >

Inverter matrix for the Clementine mission

An inverter matrix test circuit was designed for the Clementine space mission and is built into the RRELAX (Radiation and Reliability Assurance Experiment). The objective is to develop a circuit that will allow the evaluation of the CMOS FETs using a lean data set in the noisy spacecraft environment. As is shown, only nine data points are needed to acquire ten CMOS FET parameters.<<ETX>>