amplifier due to nbti is suppressed the current detection circuit does not change the threshold value at which its output voltage is inverted on the other hand when the current i s is increased to minus it does not affect the circuit operation of the current detection circuit fig2 is a circuit diagram of a current detection circuit according to a second embodiment a difference from the current detection circuit according to the first embodiment is that a pmos transistor 212 is provided instead of the nmos transistor 112 the pmos transistor 212 has a source connected to a non inversion input terminal 103 and a gate and a drain connected to a source of a pmos transistor 108 a substrate is connected to the highest power supply within the circuit since the pmos transistor 212 is connected a voltage drop of a gate voltage v g1 of the pmos transistor 108 and a pmos transistor 109 is limited the pmos transistor 212 has transistor characteristics which allow a sufficient current to flow assuming that the threshold voltage of the nmos transistor 112 is vth the following equation is established thus the voltage drop is limited by this voltage from the above a source gate voltage v sg12 of the pmos transistor 109 is represented by the following equation v sg12 u2032 v s1 u2212 v g1 u2032 v th v sg11 u2212 i u00d7 r thus the source gate voltage v sg12 of the pmos transistor 109 is prevented from becoming a voltage not greater than a constant value regardless.