| 摘要 |
PROBLEM TO BE SOLVED: To provide a constant voltage source which is compact and high pressure-resistant, and small in process variations and temperature-dependent variations. SOLUTION: According to the circuit configuration of the constant voltage source, when a current is not supplied from an output terminal VHTM to a load, a current from a current source 101 flows to a PMOS 103 and a sufficiently large current does not flow in a current-voltage converting circuit 105. Therefore the current-voltage converting circuit 105 does not generate a voltage sufficient for turning on a PMOS 104. Thus a sum of a gate voltage of the PMOS 103 and a gate-source voltage is output to the VHTM, and when a current is supplied from the output terminal to the load, an output voltage is decreased to turn off the PMOS 103. Therefore a current flowing through the current-voltage converting circuit 105 is increased, which enables the current-voltage converting circuit 105 to supply a gate voltage sufficient for turning on the PMOS 104. As a result, the PMOS 104 supplies a current to the VHTM and increase the output voltage, which result in that the output voltage is maintained in an almost constant value. COPYRIGHT: (C)2005,JPO&NCIPI
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