| 摘要 |
PURPOSE:To improve S/N nonlinearity when a range bit is different on frame switching by regarding the sum data of the output data of a fixed pattern setter and the output data of a random data generator as data to be supplemented. CONSTITUTION:A four-bit fixed pattern setter 10, three-bit M-series random data generator 11, and adder 12 which adds the output of the setter 10 and the output of the generator 11 together are provided, and the output of the adder 12 is supplied to an expanding circuit 6. The generator 11 is set to, for example, a degree n=10 of a primitive polynomial and its upper three bits (000-111) are outputted. The bit pattern of the generator 10 is set to (0100) because the output of the adder 12 is set to a region a half as large as the whole range corresponding to range bits. Consequently, an absolute error as a mean value is minimized and the nonlinearity of the S/N ratio is improved. |
