PURPOSE: To reduce the power consumption by inserting a resistor division circuit whose dividing ratio is changed by a control signal to the input side and the output side respectively to reduce the circuit scale.
CONSTITUTION: The resistor dividing circuit comprising resistors R1, R2 and R3, R4 is connected respectively to the input terminal and output terminal and the attenuation is changed by switches S13, S14 respectively. The switches S13, S14 are controlled respectively by control signals D1 and D4. That is, the attenuation is controlled by the control signals D1, D4. Furthermore, four kinds of attenuations are obtained by controlling a circuit comprising an operational amplifier A2, capacitors C9∼C12 and switches S11, S12, S15 and S16 with control signals D2 and D3.
NAKAJIMA MASAHIKO
OKADA TOMONORI
SUGA SEIICHI
