| 摘要 |
PURPOSE:To compensate the offset of a decoder, by converting the offset of the decoder into an offset digital signal at an encoder, inputting the signal to the decoder and superimposing the offset signal to a digital signal inputted externally with opposite polarity. CONSTITUTION:Before an external digital signal is inputted to a decoder 2, an offset digital signal outputted from an offset register 21 is selected at a selector 17 and inputted to the decoder 2. A controller 22 closes switches SWR and SWG of the decoder 2, operates switches SW1-SWn to connect a capacitor corresponding to the offset digital signal to a reference voltage +VR or -VR and rest capacitors to ground E. Through the connection of the capacitors to the VR and E, the external digital signal and the offset digital signal are converted respectively into analog signals and a signal subtracted with the offset digital signal can be outputted. |
