| 摘要 |
Generator for generating a sine-wave voltage has a crystal-controlled oscillator whose clock signals are divided by digital divider circuits into two pulse strings whose pulse string frequencies are in each case two times higher than the frequencies of the required sine-wave voltage. These pulse strings are alternatively fed via a changeover device (S) to a flip-flop (FF) where they are converted into a square wave at half the frequency. All harmonics are eliminated from the square wave in a low-pass filter (TP) designed as a third-order Tschebyscheff filter. In its pass band, the low-pass filter (TP) has a relative attenuation minimum which lies between the required fixed values of the frequency, such that exactly identical attenuation values and therefore identical output voltage amplitudes are created at both frequencies. <IMAGE>
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