Output circuit for a CCD with cascode depletion MOSFET loads and a feedback capacitor

摘要

Herein disclosed is an amplification circuit for realizing a substantially high sensitivity with a simple structure. The amplification circuit comprises: a first capacitor C1 for receiving a signal charge; a source-follower circuit for receiving a voltage of the first capacitor C1; an inversion amplification circuit including a source-earth type amplification MOSFET Q5 having its gate fed with the output signal of the source-follower circuit through a second capacitor C2; a feedback third capacitor C3 connected between the gate and drain of the amplification MOSFET Q5; and a switch element Q6 for feeding the gate of the amplification MOSFET Q5 with a predetermined bias voltage while the signal charge of the first capacitor C1 is being reset. The amplification MOSFET Q5 has its drain equipped as load means with a depletion type MOSFET Q4 having its gate and source connected, and the depletion type MOSFET Q4 has its source given the same potential as the substrate potential thereof.