| 摘要 |
<p>PURPOSE:To improve AD converting errors by providing an MOS transistor (TR) having the same characteristic as an MOS switch and an amplifier circuit applying a voltage amplifying twice the voltage of a non-inverting input of an operational amplifier to a drain of the MOS TR. CONSTITUTION:The source and gate of an N-MOS TR Q10 are connected to the non-inverting terminal of the operational amplifier A1 forming an integration device and a terminal voltage across capacitor C2 is doubled by using a non- inverting amplifier comprising an operational amplifier A10 and resistors R10, R11 having identical resistance and the result is fed to the drain. Through the constitution above, since the drain-source voltage of an MOS switch S4 is nearly equal to a constant voltage source Vs in the 2nd step of AD conversion, a current equal to the drain current due to tailing of the MOS switch S4 is fed by the N-MOS TR Q10 to attain compensation. Thus, the operation by a low voltage and unipolar power supply is attained and the AD converter with higher accuracy is obtained.</p> |
