| 摘要 |
A wide band constant duty cycle pulse train processing circuit where the pulse train frequency varies is proposed. The circuit serves primarily to obtain the basic clock in decoding signals encoded in the bi-phase mark code and includes a pulse-shaping or wave-shaping circuit, which receives the data signals and is followed by a low-pass filter; a differential amplifier circuit, one input of which is connected to the output of the low-pass filter and the other input of which is connected to a variable voltage source; and a current source, controlled by the differential amplifier circuit, at the input of the wave-shaping circuit determining the pulse length. The closed control loop between the output and the input of the wave-shaping circuit that determines the pulse length causes the duty cycle established at the variable voltage source to be maintained over wide ranges of the incident pulse train frequency.
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