| 摘要 |
PURPOSE:To enable a simple circuit to control a continuous resistance of FET's by forming the fixed circuit. CONSTITUTION:Gates of FET's T11-T13 of the same characteristics and that of FETT14 of the same characteristics are connected in common and sources of FET's are all grounded. The gates of respective FET's are connected to the output of operational amplifier A and the drain of FETT14 to the positive input of amplifier A. As a result, since amplifier A forms a negative feedback loop via FETT14, the output, i.e., the gate voltage of FET14 is controlled to equalized voltages applied to positive and negative inputs of amplifier A, so that the continuous resistance will vary. Accordingly, the continuous resistance of FET's T11-T13 of the same characteristics becomes equal to the resistance of FETT14. Thus, the continuous resistance of the FET's can be controlled by the simple circuit. |
