| 摘要 |
<p>To realize a suitable operation of a variable resistor even without arranging that the drain-source voltage of the variable MOS resistor be equal to that of a reference MOS resistor. The gate voltage (V<SUB>p12</SUB>) of a variable MOS resistor is controlled with reference to a gate voltage (V<SUB>p11</SUB>) controlled such that a voltage occurring across a reference MOS resistor is constant as a reference voltage. A series connection of resistors (R<SUB>11</SUB>,R<SUB>12</SUB>) having the same resistance is connected between and in parallel with the drain and source of the reference MOS resistor. One half of the drain-source voltage (V<SUB>ds</SUB>) of the reference MOS resistor is detected from a midway junction between the series connected resistors. A voltage, which is obtained by subtracting the one half of the drain-source voltage (V<SUB>ds</SUB>) from the gate voltage (V<SUB>p11</SUB>) of the reference MOS resistor, is established as the gate voltage (V<SUB>p12</SUB>) of the variable resistor.</p> |
