| 摘要 |
PURPOSE: A back bias voltage level detector is provided to cut off an unnecessary operation of a pump generated due to bouncing of a supply voltage(Vcc) or a ground voltage(Vss) and to maintain a constant back bias voltage level by adjusting the number of differential amplifiers and MOS transistors for controlling the pump. CONSTITUTION: The circuit includes a differential amplifier(40) and the first and second input circuits(50,60). The differential amplifier receives two output signals of the first and second input circuits and amplifies the difference of the two signals. The first input circuit has the first PMOS transistor, a resistor(R2), a capacitor(C1) and a plurality of the first PMOS transistors. The first PMOS transistor outputs a voltage in response to a control signal(CS). The resistor connects the first PMOS transistor with a node and adjusts the output of the first PMOS transistor. The capacitor is charged with a voltage of the node. The first PMOS transistors are serially connected between the node and a back bias voltage(VBB). The output of the first input circuit is applied to an input terminal of the differential amplifier. The second input circuit has the second PMOS transistor, a resistor(R3), a capacitor(C2) and a plurality of the second PMOS transistors. The second PMOS transistor outputs a voltage in response to the control signal. The resistor connects the second PMOS transistor with a node and adjusts the output of the second PMOS transistor. The capacitor is charged with a voltage of the node. The second PMOS transistors are serially connected between the node and the ground voltage(Vss). The output of the second input circuit is applied to the other input terminal of the differential amplifier.
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