POWER GAIN STABILIZING CIRCUIT OF DOUBLE CONVERSION TUNER

摘要

The present invention stabilizes the power gain of the double conversion tuner, which can obtain a constant power gain by designing a high gain from the beginning toward the high frequency of the RF output signal input to the first mixing part. A circuit comprising: an RF amplifier for converting an input received signal into a frequency signal of a required band having a constant gain, and a frequency signal supplied from the RF amplifier and an oscillation frequency of the first oscillator to be mixed into an intermediate frequency signal. And a second mixing section which converts the intermediate frequency signal of the first mixing section with the oscillation frequency of the second oscillation section and outputs the final intermediate frequency output signal. The RF amplifier unit may be coupled to a base input terminal and a collector output terminal of a transistor, respectively. First and second capacitors, a third capacitor and a first resistor connected to the base and the collector of the transistor to regulate voltage feedback, a second resistor connected in parallel to the emitter of the transistor to suppress the gain on the low frequency side, and Since it comprises a fourth capacitor for compensating the gain of the high frequency side, and a fifth capacitor and a sixth capacitor connected between the base, the emitter and the collector of the transistor to compensate the gain of the high frequency side, With the use of the fifth resistor and the third, fourth, and fifth capacitors, the output of the RF amplifying unit input to the first mixing unit increases the amplification gain toward the high frequency side, thereby achieving stable power gain.