| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a drive unit for a load circuit capable of downsizing a multi-source FET (T1), by reducing the measurement errors caused by an offset voltage that an amplifier AMP 1 possesses. Ž<P>SOLUTION: The drive unit for the load circuit comprises: a reference current generating circuit 11, which includes the amplifier AMP 1 and a resistor R1 and generates a reference current I1 that varies in proportion to voltages Vds at both ends of a main FET (T11); and a criterion current generating circuit 12, which includes an amplifier AMP 2 with the same offset voltage as that of the amplifier AMP 1 and a resistor R2 and generates a criterion current I2 that varies, in proportion to voltages at both ends of a sub FET (T12). Then, a difference current (I1-I2) is generated, by subtracting the criterion current I2 from the reference current I1 and in the case where the difference current is a positive value, and a voltage corresponding to the difference current is generated. When the generated voltage reaches a threshold voltage, MOSFETs (M3), (M4) are turned on and the cut-off state of the multi-source FET (T1) is maintained. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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