| 摘要 |
PROBLEM TO BE SOLVED: To more quickly recover an amplifier from a drift state.SOLUTION: A fixed time after a detection circuit 7 detects a signal level drop of an input signal, a control section 8 turns Signal 2 from on to off. Signal 2 turned off stops applying a drain voltage. The control section 8 later turns Signal 3 from on to off. Signal 3 turned off brings a variable resistor 52 to a low resistance state to change a gate voltage from a first potential to a second potential having a value of not less than a ground potential. After keeping, for a predetermined time, the gate voltage at the value of not less than the ground potential and the drain voltage from being applied, the control section 8 turns Signal 3 on to bring the gate voltage to the first potential. The control section 8 next turns Signal 2 on to apply the drain voltage. |
