The Cryogenic Temperature Behavior of Bipolar, MOS, and DTMOS Transistors in Standard CMOS

Harald Homulle,Fabio Sebastiano,Lin Song,Edoardo Charbon

doi:10.1109/jeds.2018.2798281

Harald Homulle, Fabio Sebastiano + Show 2 more

Open Access

https://doi.org/10.1109/jeds.2018.2798281

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Abstract

Both CMOS bandgap voltage references and temperature sensors rely on the temperature behavior of either CMOS substrate BJTs or MOS transistors in weak inversion. Bipolar transistors are generally preferred over MOS transistors because of their lower spread. However, at deep-cryogenic temperatures, the performance of BJTs deteriorates due to a significant reduction in current gain and a substantial increase in the base resistance. On the contrary, MOS devices show more stable performance even down to 4 K, but accurate device characterization for the design of such a circuit is currently missing. We present the characterization and analysis over the temperature range from 4 K to 300 K of both substrate bipolar PNP transistors and MOS transistors in standard and dynamic threshold MOS (DTMOS) configurations implemented in a standard 0.16- $\mu \text{m}$ CMOS technology. These results demonstrate that employing MOS or DTMOS enables the operation of bandgap references and temperature sensors in standard CMOS technologies even at deep-cryogenic temperatures.

Highlights

Cryogenic electronics is used in several applications, either for its improved performance, e.g., for the reduced thermal noise in the read-out for high-energy and nuclear physics experiments [1], [2], or for its operability in harsh environments, e.g., in space and quantum computing applications [3], [4]
For the same reasons, existing circuits operating at cryogenic temperatures comprise only bandgap references relying on alternative processes, such as SiGe BiCMOS [13], and a non-conclusive attempt to implement a CMOS bandgap-based temperature sensor operating at 93 K [14]
We extend our prior results on the characterization of substrate PNPs presented in [12] by including the characterization of MOSFETs in standard and dynamic threshold configuration fabricated in a standard 0.16 μm CMOS technology over the temperature range from 4 K to 300 K

Summary

Introduction

Cryogenic electronics is used in several applications, either for its improved performance, e.g., for the reduced thermal noise in the read-out for high-energy and nuclear physics experiments [1], [2], or for its operability in harsh environments, e.g., in (deep) space and quantum computing applications [3], [4]. Any CMOS subsystem, such as voltage regulators, analogto-digital and digital-to-analog converters, requires a reference voltage, usually generated by a bandgap-reference circuit that can be implemented with either bipolar or MOS transistors in weak inversion as core devices. Especially substrate PNP transistors (Fig. 1(a)), readily available in any CMOS process, are generally preferred for their lower spread compared to MOS transistors (Fig. 1(b)) [6]–[9]. Prior research on CMOS devices was limited to characterizing substrate PNP transistors over the industrial temperature range (−55◦C–125◦C) [10]. For the same reasons, existing circuits operating at cryogenic temperatures comprise only bandgap references relying on alternative processes, such as SiGe BiCMOS [13], and a non-conclusive attempt to implement a CMOS bandgap-based temperature sensor operating at 93 K [14]

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