| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a sensor circuit capable of stabilizing an output from a C-V conversion circuit (charge amplifier) in a short time. <P>SOLUTION: A switch 49 is connected in parallel to a capacitor 42 connected between an inversion input terminal and an output terminal of an operational amplifier 41, and the switch 49 is turned on to form structure of constituting a buffer circuit in the operational amplifier 41. Just after an electric power source is fed to the sensor circuit, the switch 49 is turned on at first, a MOS resistance 43 is brought into a low resistance condition, the switch 49 is turned off when a voltage of the electric power source exceeds the first threshold value Vref1 and when a voltage of a step-up electric power source exceeds the second threshold value Vref2, and the MOS resistance 43 is switched thereafter from the low resistance condition to a high resistance condition. A time until outputs of the charge amplifier circuits 22, 31, 32 are stabilized is shortened thereby. <P>COPYRIGHT: (C)2007,JPO&INPIT |
