| 摘要 |
The circuit according to the present invention makes it possible to obtain a summing of a high frequency (F1) with a very much lower frequency (f0). It comprises a first phase-slaving loop (10) having a voltage-controlled oscillator (14) producing the frequency (F1), and a second phase-slaving loop (20) supplying the sum (F2) of the two frequencies (F1 + f0). These two loops (10, 20) are linked by means of a frequency-mixer circuit (23) inserted into the return line of the summing loop (20). The output of the mixer (23) passes through a low-pass filter (25), before being applied to the input of a phase comparator (21), associated with the second summing loop. The reference input of the comparator (21) receives the frequency (f0). The circuit also comprises a loop guidance system (30) connected between the control inputs of the oscillators (14, 24) of the respective loops, making it possible to deflect any frequency control variation from the oscillator (14) producing (F1), to the oscillator producing the summing frequency (F2), so as to prevent the condition F1 > F2, which would tend to cause the summing loop (20) to diverge. <IMAGE>
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