Using the design techniques presented in the previous chapters, many circuitand device-related errors inCMOSsmart temperature sensors can be sufficiently reduced. However, variations in the base-emitter voltage of the bipolar transistors (as a result of process spread and mechanical stress) will ultimately limit the achievable accuracy. Trimming, and an associated calibration procedure, are needed to correct for these variations. If high accuracy is desired, traditional calibration techniques are time-consuming and therefore costly. This chapter presents three alternative calibration techniques that combine accuracy with low production costs: batch calibration, calibration based on Δ
measurement, and voltage reference calibration.