| 摘要 |
PURPOSE:To improve the tracking error from a medium tracking frequency to a high tracking frequency, by providing a compensating circuit applying a compensating voltage to a varactor diode of an antenna tuning circuit. CONSTITUTION:When the received frequency is within a range between tracking frequencies fH(1,400kHz) and fM2(1,200kHz), transistors (TRs) Q1-Q3 are turned on, a diode D3 is biased forward, a current flows to a resistor R4 and the diode D3, and the compensating voltage is applied from a compensating circuit 16 to the varactor diode D1 of an antenna circuit 12. The compensating voltage is selected so that the tracking error is zero at the receiving frequency fM2(1,200 kHz). Thus, the tracking error between the medium tracking frequency (fM: 1,000kHz) and the high tracking frequency (fH:1,400kHz) is improved. |
