High Temperature SOI CMOS Voltage Reference

Abstract

The purpose of this study was to design a Silicon-On-Insulator (SOI) CMOS band-gap voltage reference that achieves a temperature dependence of 300 ppm/ C. The procedure consisted of three major portions: test, design and simulation, and layout for fabrication. Measurements were completed on two SOI structures, the gated-diode and parasitic bipolar junction transistor (BJT), which determined the gated-diode was more suitable for the voltage reference. The band-gap voltage reference was designed and simulated using the Cadence Design Suite. Finally, the design was prepared for fabrication using the Cadence Design Suite. The circuit was fabricated and tested for comparison against design and simulation results. The measurements conducted on the gated-diode and BJT indicated the gated-diode is the preferred solution in the voltage reference. A new model was developed to simulate the measured temperature behavior of the device. The gated-diode exhibited temperature dependence undocumented in current literature. Several small additions to recently published eorts provided improvements in the simulated performance of the circuit, particularly in extending the range of operating temperatures. The design's simulation results exhibited a temperature dependence of 182 ppm/ C, voltage supply dependence of 123 ppm / V, consumes 180 uW of power, and occupies 460 um x 3100 um area. The fabricated circuit achieved a voltage supply dependence of 975 ppm/ V, a minimum supply of 2.5 V, and consumes 310 uW of power. The temperature dependence was measured as 120 ppm / C at temperatures up to 120 C, and 202 ppm/ C at 180 C.