Patent ID: 8461932

Claim:
A signal amplifier comprising: an inverting amplification circuit comprising a first voltage terminal connected to a first voltage line that is applied with a first voltage, a second voltage terminal connected to a second voltage line that is applied with a second voltage that is different from the first voltage, an inverting input terminal connected to a signal line into which a signal is input, an output terminal connected via a resistance element to the inverting input terminal and connected to a section having an inductive component, a first protected switching element disposed between the first voltage line and the output terminal, which switches a conducting state between the first voltage line and the output terminal during normal operation to a non-conducting state, and a second protected switching element disposed between the second voltage line and the output terminal, which switches a conducting state between the second voltage line and the output terminal during normal operation to a non-conducting state; a first conducting switching element comprising a first terminal connected to the first voltage line, a second terminal connected to the signal line, and a first control terminal, the first conducting switching element switching a non-conducting state between the first terminal and the second terminal during normal operation to a conducting state when an ON voltage is applied to the first control terminal; a second conducting switching element comprising a third terminal connected to the second voltage line, a fourth terminal connected to the signal line, and a second control terminal, the second conducting switching element switching a non-conducting state between the third terminal and the fourth terminal during normal operation to a conducting state when an ON voltage is applied to the second control terminal; and a control section that effects control such that when an overcurrent flows in the first voltage line, the first protected switching element and the second protected switching element are switched to a non-conducting state after switching the first conducting switching element to a conducting state and switching the second conducting switching element to a non-conducting state, and effects control such that when an overcurrent flows in the second voltage line, the first protected switching element and the second protected switching element are switched to a non-conducting state after switching the first conducting switching element to a non-conducting state and switching the second conducting switching element to a conducting state.