| 摘要 |
PURPOSE:To improve DNL characteristics and precision by shifting the code output of an AD converter and dropping lower bits of the code output to obtain a prescribed data output. CONSTITUTION:An analog input VIN and an offset voltage EOS are inputted to an adding circuit 2, and the output is outputted to an M-bit AD converter 1. A digital memory 3 shifts a code output (p) of the AD converter 1 by number of codes except 2<n> (n is the number of unused bits) and converts the shifted code output to data consisting of a prescribed number N of bits and outputs this data as a data output (q) (M=N+n). Data outputs whose lower one bits are dropped after one code shift are shown in a table. Since the number of used bits is reduced (lower bits are dropped) after one code shift, there are certainly a pair of data outputs having a reat difference in bit pattern in one group. Consequently, positive and negative nonlinear errors in this part are cancelled by each other to improve DNL characteristics. |
