ELECTRIC CHARGE DETECTION CIRCUIT

摘要

Provided is an electric charge detection circuit capable of readily performing gain adjustment on the input side of a differential amplification circuit. One end of a physical quantity detection sensor (21, 22) configured from either a charge-generating sensor or a variable capacitance-type sensor is connected to a negative electrode input terminal in the differential amplification circuit (1), and the other end is connected to a positive electrode input terminal in the differential amplification circuit (1). A feedback resistor (Rf) and a feedback capacitor (Cf) are connected in parallel between an output terminal and the negative electrode input terminal in the differential amplification circuit (1), and a cancellation resistor (Rc) and a cancellation capacitor (Cc) are connected in parallel between the positive electrode input terminal and a reference voltage in the differential amplification circuit (1). Drain voltage adjustment circuits (12, 13), that adjust the drain voltage of at least one of two field effect transistors (FET1, FET2) to which positive/negative differential input from the differential amplification circuit (1) are separately input, are provided, and gain adjustment of at least one of either the positive or negative differential input has been made possible.