INFRARED RECEIVER HAVING AN AUTOMATIC GAIN CONTROL CIRCUIT FOR SELECTIVELY CHARGING/DISCHARGING WITH REGARDS TO NOISE AND AN INPUT SIGNAL AND AN AUTOMATIC GAIN CONTROL METHOD, PARTICULARLY CONCERNED WITH SELECTIVELY CONTROLLING A CHARGE CURRENT AND A DISCHARGE CURRENT FOR POWER NOISE AND AN INPUT SIGNAL

摘要

PURPOSE: An infrared receiver having an AGC circuit for selectively charging/discharging with regards to noise and an input signal and an AGC method are provided to intercept power noise by lowering a gain of an amplifier, and to increase the gain by adding the second charging/discharging time constants and the second discharge current to the first time constants and the first current in a data idle section, thereby stably generating an output signal. CONSTITUTION: A delay circuit unit(72) comprises as follows. A resistance(80) is connected to a supply voltage(VCC). The first transistor(81) inputs a discharge signal(S_DIS) via a base terminal between the resistance(80) and a ground voltage. The second transistor(83) inputs an output of the first transistor(81) via a base terminal between a reference current source(82) and the ground voltage. A capacitor(84) is charged/discharged by a reference current(Iref_d) of the reference current source(82), depending on whether the second transistor(83) is turned on/off. A comparator(85) compares a capacitor voltage with the second reference voltage(VREF2).