Digital Calibration Method for High Resolution in Analog/RF Designs
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Transistor random mismatch continuously poses challenges for analog/RF circuit design for achieving high accuracy and high yield as the process technology advances. Existing statistical element selection (SES) design method can improve transistor matching property, but it falls short of being a general calibration method due to its limited calibration range. In this dissertation, we propose a high resolution digital calibration method, called extended statistical element selection (ESES). As compared to the SES method, the ESES method not only provides wider calibration range, but also it results in higher calibration yield with same calibration resolution target. Two types of ESES based calibration application in analog/RF circuits are also proposed. One is current source calibration and the other is phase/delay calibration. To verify this proposed digital calibration method in circuit implementation, we designed, fabricated and tested a wideband harmonic rejection receiver design. The receiver utilizes ESES-based gain and phase error calibration for improving harmonic rejection ratios. With the high calibration resolution provided by the ESES method, after calibration, we achieved best-in-class harmonic rejection ratios. To extend the application of the proposed method, we further designed a current-steering D/A data converter (CS-DAC). The CS-DAC utilizes ESES-based amplitude and timing error calibration for improving linearity performance. Simulation results showed that we can achieve more than one order of magnitude linearity improvement after performing ESES-based calibration in the CS-DAC.
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