Radiation Hardened CMOS/SOS Code Generator for Space Applications.

摘要

The primary objective of this program was to design, fabricate, and test a radiation hardened LSI code generator array suitable for use in the NAVSTAR Global Positioning System (GPS). The LSI array developed is a mask programmable custom cell CMOS/SOS array which was fabricated using both standard processing and radiation hardened processing. Designated TCS102, this array contains two 12-stage pseudorandom sequence generators and a 12-stage synchronous counter along with associated control logic. The Precision (P) Code Generator in the GPS operates with a fixed 10.23-MHz clock. The radiation hardness objectives for this development effort were a total dose hardness of 1 million rads(Si), with a minimum transient upset level of 2 x 10 to the 10th power rads(Si)/s, with a goal of 10 to the 11th power rads(Si)/s. Extensive computer simulations were made to predict circuit performance over the full range of total dose radiation and ambient temperature to +125 C. Design techniques used to obtain high speed include: the elimination of long signal paths, retiming of all control signals on the array, optimizing device widths for maximum speed, and designing all devices with a channel length of 6.25 micrometers. Radiation hardening techniques included: clamped channels on P transistors, elimination of transmission gates from the design, use of gated diodes for the input protection, and restriction of stacked devices to a maximum of three.