Title :
A multibit ΣΔ modulator in floating-body SOS/SOI CMOS for extreme radiation environments
Author :
Edwards, Christopher F. ; Redman-White, William ; Bracey, Mark ; Tenbroek, Bernard M. ; Lee, Michael S L ; Uren, Michael J.
Author_Institution :
Dept. of Electron. & Comput. Sci., Southampton Univ., UK
fDate :
7/1/1999 12:00:00 AM
Abstract :
This paper presents the design of an experimental first-order ΣΔ modulator with 4-bit internal quantization, fabricated in a 1.5-μm space-qualified radiation-hard partially depleted silicon-on-sapphire (SOS) digital CMOS process. This converter architecture has been chosen partly to allow investigation into the design of a range of common analog functions with two key issues in mind: one of technology and one environmental. First, both the architecture and the circuit design are optimized using a variety of unconventional techniques to account for the influence of extreme bias-dependent, radiation-induced threshold-voltage shifts of up to 1 V, as well as poor 1/f device noise. Second, the circuitry is specially adapted to accommodate the floating-body behavior of this type of process, wherein drain conductance varies considerably with drain bias and frequency. The design techniques are directly applicable to very large-scale-integration silicon-on-insulator (SOI) design, where similar device physics are encountered. Notwithstanding the severe constraints on the design, the fabricated circuit provides 9.7 bits of dynamic range in a 63-kHz signal bandwidth, only degrading to 9.1 bits after 23 Mrad(Si) of total dose γ radiation
Keywords :
1/f noise; CMOS integrated circuits; gamma-ray effects; integrated circuit design; integrated circuit noise; mixed analogue-digital integrated circuits; radiation hardening (electronics); sigma-delta modulation; silicon-on-insulator; 1.5 micron; 1/f device noise; 23 Mrad; 63 kHz; ADC; Si-Al2O3; VLSI SOI design; bias-dependent threshold-voltage shifts; converter architecture; digital CMOS process; drain conductance variation; extreme radiation environments; first-order ΣΔ modulator; floating-body SOS/SOI CMOS; gamma radiation; internal quantization; multibit ΣΔ modulator; partially depleted SOS CMOS process; radiation-hard CMOS process; radiation-induced threshold-voltage shifts; sigma-delta modulator; space-qualified CMOS process; CMOS process; CMOS technology; Circuit noise; Circuit synthesis; Design optimization; Digital modulation; Frequency; Quantization; Space technology; Working environment noise;
Journal_Title :
Solid-State Circuits, IEEE Journal of
