| 摘要 |
PURPOSE:To always secure the optimum threshold voltage for the MOSFET by providing the following means: the application means to apply the bias potential to the semiconductor substrate; the means to detect the change of the bias potential; and the by-pass means to control the current amount via the detecting means respectively. CONSTITUTION:The circuit consists of the following component units: oscillator 11; driving circuit 12; coupling capacity 13; MOS diode Q11 and Q12; reference voltage generator circuit 21; circuit 23 which compares the reference voltage of node 22 with the threshold voltage of MOSFET element 14 and then generates the control voltage; and MOSFET element Q15 which give by-pass to the substrate bias voltage respectively. In such constitution, the output voltage of circuit 23 increases in case the leak current reduces and with the substrate bias voltage increased. Thus, the increment can be prevented for the substrate bias voltage. On the contrary, in case the leak current is large, the decrement of the substrate bias voltage is prevented to always secure a constant level for the threshold voltage of the MOSFET within the chip. |
