| 摘要 |
PURPOSE: To provide a charge pump which has its output potential varying from an optional power potential through the ground potential without virtually using any steady power supply, has the current source and sink functions which are substantially equivalent to each other and outputs a current that is not substantially affected by the power fluctuation. CONSTITUTION: When a transistor TR 50 is activated by a high logical pump control signal, a current flows from a power supply 66 through resistances 52 and 60 and TR 54 and 62. These resistances and TRs are selected, so that the amounts of currents flowing through the resistances 52 and 60 are substantially equal to each other. Meanwhile, the amounts of currents flowing through the TR 54 and 62 are also set substantially equal to each other. The amounts of currents which are outputted from the TR 64 and 56 are substantially equal to each other. Furthermore, the TR 64 and 56 can be set proportional to the TR 62 and 54 respectively in the necessary relationship owing to the source or sink fluctuation of the current amount. |
