| 摘要 |
PURPOSE:To eliminate tracking errors by correcting voltage given to a high frequency tuning device and a local oscillating device to specified relation and thereby changing differential frequency between tuning frequency and local oscillation frequency over whole range of receiving band. CONSTITUTION:To reduce tracking errors using the same control voltage, it is desirable to select different characteristics between voltage-capacity characteristic of a varactor diode for high frequency tuning and voltage-capacity characteristic of a varactor diode for local oscillation. Actually, however, it is difficult to select varactor diodes that correspond to the characteristics. Accordingly, reduction of tracking errors is contrived by making apparent characteristics different between the varactor diode 23 for high frequency tuning and varactor diode 53 for local ascillation by properly correcting output of an active filter 63 given to the oscillation circuit 50 side using varactor diodes having the same characteristics. |
