| 摘要 |
PURPOSE:To enable to obtain stable performance, by reducing the gain difference between high and low channels, through the variable biasing of electronic tuner active element with the use of channel selection turning voltage. CONSTITUTION:The resistor 7 is attached to the gate G of the active element FET 1 in the RF amplifying element bias circuit, and the resistor 7 is connected to the tuning voltage terminal 8. To this terminal 8, the tuning voltage VT applied to the varactor diode constituting the tuning circuit of tuner (having performance that it increases with increased frequency) is fed. That is, G2 is variably biased with VT, enabling to obtain the gain G which has about constant frequency response 50 (solid lines). Dotted lines show conventional performance. |
