| 摘要 |
PURPOSE:To obtain an exclusive NOR circuit where an output of a N-channel FET is not decreased by a threshold level when both of two input signals are at 'H' by adding a P-channel FET outputting an 'H' level when both two input signals are at 'H' and a control circuit of the FET in the circuit constitution of MOSFETs. CONSTITUTION:A P-channel FET 21 is controlled by a control circuit 24. The on-resistance ratio of the FET 21 and the N-channel FETs 13, 14 is decided so that the output C goes to 'H'-Vth or below when both are turned on simultaneously and a through-current flows. With both input signals A, B at 'H', a series circuit 9 of the P-channel FET is turned off and a series circuit 16 of the N-channel FET is turned on. A level of 'H'-Vth is fed to a terminal 7 from terminals 3, 5, but the gate of the P-channel FET 21 goes to 'L' and an 'H' level is outputted to the terminal 7 from a power terminal 20 through the FET 21, resulting that the output signal goes to 'H', and even when both inputs A, B are at 'H', an exclusive NOR circuit obtaining an output without decreased Vth is obtained even when both inputs A, B are at 'H'.
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