| 摘要 |
PURPOSE:To improve the frequency characteristic of a multiplying-factor controlling device, and enable a high-speed scanning by either changing the gain of an amplifier contained in a multiplying-factor controlling system circuit interlockingly with selection of the resistances of a variable resistance circuit, or changing the gain of the said amplifier by inserting another amplifier in series with the said amplifier. CONSTITUTION:An auxiliary amplifier 7, as illustrated in the figure, is installed between an error amplifier 2 and a power amplifier 3. The gain of the amplifier 7 changes according to the resistance change-over carried out with a change-over switch (S) of a variable resistance circuit 5, and becomes larger as the resistance value of the circuit 5 is made smaller (as the multiplying factor is made lower). During the time when the multiplying factor is low, for example, when the resistance value is adjusted to (r1) by the change-over of the switch (S), the gain of the amplifier 7 changes into (G1) interlockingly with the above change-over. As the result, the frequency characteristic of the open loop gain of the multiplying-factor controlling system circuit is improved by a frequency of (DELTAf), as indicated by (Q1') in the figure, due to the above gain (G1). Consequently, a high-speed scanning of an over (f0) frequency is enabled even during the time of a low multiplying factor. |
