Nonlinearity analysis of the boosted bucket brigade device for high-speed charge-domain ADCs

The charge-domain analog-to-digital converter (ADC) based on boosted bucket-brigade devices (BBD) is an opamp-less pipelined ADC architecture, which can provide high conversion speed with very low power consumption compared with traditional pipelined ADC architectures. However, the charge transfer characteristics of the MOS BBD exhibits severe nonlinearity, which poses a hard limit on the linearity performances of the pipelined ADC. In this paper, the influences of the circuit parameters of the BBD on its linearity performance are analyzed theoretically and verified by simulation. The results of analysis and simulation show that the nonlinear response of boosting amplifier has the most serious impact on the linearity of the BBD. Based on the analysis results of the paper, relatively higher linearity of charge-domain ADCs can be obtained by choosing reasonable circuit parameters for the BBDs used in the ADC.