SEMICONDUCTOR DEVICE, AND AMPLIFYING CIRCUIT, AND ACTIVE FILTER

摘要

PROBLEM TO BE SOLVED: To provide a semiconductor device, an amplifying circuit, and an active filter which can fix the resistance values of resistance elements irrespective of temperatures, and can simplify the circuit constitution. SOLUTION: A secondary biquad filter circuit 100 is composed of a differential amplifier A1, transconductance amplifiers gm5 and gm6, buffers B1 and B2, and resistors R1, R2, and R3. The transconductance amplifier gm5 is composed of resistors 17, 18, RX1, and RY1, and transistors 31, 32, 33, and 34, and a current source IS3. Here, it is possible to fix the conductance of the transconductance amplifiers gm5 and gm6 irrespective of the temperature, by connecting the resistor RX1 having negative temperature property and the RY1 having positive temperature property in series.