| 摘要 |
<p>A low-noise amplifier used in a small-size tuner should have a performance to reduce power consumption and noise. In order to effectively reduce the noise, the amplifier used at the initial stage of the tuner can reduce a tertiary mutual modulation distortion. However, this requires a low-noise amplifier which can variably adjust a distortion amount by a signal from outside. For this, an output from the amplifier (9) of the initial stage is amplified by a main amplifier (20) and the output obtained is added by an output from a distortion compensation amplifier (30). The distortion compensation amplifier is formed by four FET (Q3 to Q6) and a constant current circuit (CC1). Q5 and Q6 which are biased are driven by the input signal via Q3 and Q4 so as to generate a tertiary distortion having an inverse phase as compared to the input signal, thereby cancelling the distortion.</p> |
