This paper covers the design and testing of a high temperature signal conditioning unit for integration with temperature and strain gauge sensors. The developed signal conditioning unit system includes an instrumentation amplifier, a single-ended to differential converter, an Analogue to Digital converter, and an ARINC 429 transmitter. This unit was designed and fabricated on 1 μm Silicon-on-Insulator CMOS (Complementary Metal Oxide Semiconductor) technology and has been characterized up to 225 degrees Celsius.