Low-Power Precision Voltage References

Abstract

Temperature-insensitive precision voltage references are critically needed for passive wireless microsystems. Although bandgap voltage references are widely studied and numerous designs are available, the rapid reduction of supply voltages, the need for precision voltage references, and the low-power consumption requirement of passive wireless microsystems impose stringent constraints on the design of voltage references. This chapter deals with the principles and design of CMOS voltage references. The chapter starts with a brief examination of the f gure-of-merits that characterize the performance of voltage references in Section 5.1. It is followed by an in-depth investigation of the temperature-dependent characteristics of semiconductors and MOS devices in Section 5.2. First-order voltage references are studied in Section 5.3 while high-order voltage references are dealt with in Section 5.4. The performance of recently reported f rst-order voltage reference and that of high-order voltage references such as temperature coeff cient, power consumption, power supply rejection ratio, and minimum supply voltage are compared. Section 5.5 focuses on the design of ultra low-power voltage references where devices operate in weak inversion. These voltage references are of particular importance to passive wireless microsystems. The chapter is concluded in Section 5.6.