| 摘要 |
PURPOSE:To improve the S/N of a signal outputted serially by providing a differential means inputting each output of the 1st and 2nd read means and outputting a signal corresponding to the difference. CONSTITUTION:Signal input terminals S1-Sm are connected to a common signal line 102 via analog switches SWt1-SWtm respectively, further analog switches SWr1-SWrm are provided, other terminals are connected to a common line 103, the common signal line 102 and the common line 103 are connected to drains of transistors (TRs) 107, 108 and connected to gates of field effect TRs 110, 111 of source follower constitution respectively. An Sig terminal and a Comp terminal are connected respectively to the non-inverting terminal and the inverting terminal of a differential amplifier 112, a noise due to a gate- source capacitance of the analog switches SWt1-SWtm and a noise due to a gate-source capacitance of the analog switches SWr1-SWrm are cancelled together and a signal at the signal input terminals S1-Sm is outputted from an output terminal. |
