| 摘要 |
PURPOSE:To simplify constitution by coding an input analogue signal in a linear A/D converter after amplifying this signal is a variable gain amplifier and by making the signal nonlinear in the stage of the variable gain amplifier. CONSTITUTION:It is supposed that the value obtained by amplifying input analogue signal Ain with a minimum gain by variable gain amplifier 41 and converting this signal to a three-bit digital signal by A/D converter 42 is (011). Control gate circuit 43 where this digital signal is input indicates to amplifier 41 that this signal belongs to prescribed (10) out of nonlinear classifications, and stores (10) in upper bit stage 44-1 of register 44. Amplifier 41 is set to a gain so that signal Ain of the (10) level may be magnified up to the maximum dynamic range of converter 42, and this signal is held in a sample hole circuit and so on and is digitized with a current level scale and is stored in lower bit stage 44-2 of register 44 as it is and is coded to a nonlinear code. Thus, constitution can be simplified. |
