| 摘要 |
<p>It is desired to vary the conversion gain in a mixer circuit to reduce the gain variation within one frequency band. <??>A television tuner according to the invention has a balanced mixer circuit (24) for converting television signals into intermediate-frequency signals. The mixer circuit (24) includes a first transistor 1 and a second transistor (2) for amplifying the television signals, the emitter of the first transistor (1) being connected to the emitter of the second transistor (2) through a gain-setting resistance (3); a first constant-current source (4) connected to the emitter of the first transistor (1); and a second constant-current source (5) connected to the emitter of the second transistor (2). Reactance means (6) is connected in parallel to the gain-setting resistance (3). The reactance of the reactance means (6) decreases as the frequency increases. <IMAGE></p> |
