| 摘要 |
PROBLEM TO BE SOLVED: To provide a highly precise pull-up/pull-down circuit capable of highly precisely matching a pul-up current and a pull-down current with each other in their values. SOLUTION: The highly precise pull-up/pull-down circuit 1 comprises P-channel transistors TP1, TP2, N-channel transistors TN1, TN2, a reference voltage source 11, and a control circuit 12. The control circuit 12 adopts a configuration of an operational amplifier circuit, a voltage Vref at nodes NA, NB is given to a negative (-) input terminal, and the feedback configuration controls a voltage at a connecting point (point C) between the P-channel transistor TP2 and the N-channel transistor TN2 to be equal to the voltage Vref. In this case, since a current Ipuo is equal to a current Ipd and the current Ipuo is accurately mirrored to the current Ipd and the current Ipdo is accurately mirrored to the current Ipd, the circuit 1 can match the pull-up current Ipu and the pull-down current Ipd with each other in their values highly precisely. COPYRIGHT: (C)2008,JPO&INPIT
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