| 摘要 |
PURPOSE:To decrease the leakage of a carrier of a balanced modulation signal by using a transfer switch so as to switch the gain of an operational amplifier thereby decreasing the difference of gains before and after the changeover. CONSTITUTION:A modulation signal 11 is inputted to an inverting input terminal (-) of the operational amplifier 1 via a resistor 3 and an output signal 13 is fed back to the inverting input terminal (-) via a resistor 4. On the other hand, the modulation signal 11 or a zero potential being a mean level of the modulation signal is inputted to a noninverting input terminal (+) of the operation amplifier 1 while the transfer switch 2 is switched by using a carrier signal 12. Thus, since the difference of gains of the operational amplifier 1 before and after the changeover is decreased, the leakage of the carrier of the balanced modulation signal is reduced.
|
