| 摘要 |
PURPOSE:To improve the sensitivity of a receiver of frequency synthesizer type, by using a digital control IC having a device possible for switching a time division output and a normal output for an output line for input key detection, for reducing noise due to the key detection. CONSTITUTION:A frequency dividing ratio of a programmable frequency divider 9 of the receiver of synthesizer type is inputted from the digital control IC15 via output terminals 25. A display controlling signal is outputted from an output group 24 of the IC25 and a received frequency is displayed on a display 13. FETs QA-QD are connected between scanning output lines 20-23 of the key of a key matrix circuit 14 of the IC15 and a power supply VDD, and an OR gate 41 is connected to each of detecting lines 16-19. Further, an output of the gate 41 is inputted to a control terminal of an oscillator 44 for key scanning signal generation and to a control terminal via a delay circuit 42. Further, the output line for input key detection is changed over for the time division output and the normal output, thereby reducing noise due to key detection. |
