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    • 8. 发明公开
    • Phase-locked loop frequency synthesizer
    • 频率合成锁相环。
    • EP0044156A1
    • 1982-01-20
    • EP81302908.9
    • 1981-06-26
    • JOHN FLUKE MFG. CO., INC.
    • Erps, Floyd D.Fried, Raymond L.
    • H03L7/22H03B21/02H03K21/36
    • H03K23/665H03K23/667H03L7/185
    • A programmable divide-by-N phase-locked loop having a pulse incrementor circuit (12) and a single sideband mixer circuit (14) embedded in the loop feedback path is disclosed. In each disclosed arrangement, one input port of the single sideband mixer (14) receives the signals supplied by the phase-locked loop voltage-controlled oscillator (16) and, depending upon whether the mixer employed is configured for supplying an upper sideband signal or a lower sideband signal, either increases or decreases the frequency of the phase-locked loop feedback signal by a factor fs, where f s is the frequency of a control signal applied to the second input port of the single sideband mixer (14). The pulse incrementor circuit (12) receives the signal supplied by the single sideband mixer (14) and, depending on whether the pulse incrementor (12) is configured for deleting signal pulses or adding signal pulses, either decreases or increases the average frequency of the signals supplied to the phase-locked loop programmable divider by a factor f d , where f d is the frequency of a control signal applied to the pulse incrementor Since the phase-locked loop synchronizes or locks when the phase of the signal supplied by the programmable divider is equal to the phase of a reference frequency f" which is supplied to the phase-locked loop phase detector, the arrangement causes the phase-locked loop voltage-controlled oscillator to supply a signal at a frequency of Nf r ±fd±f s , where N is the selected divisor of the phase-locked loop programmable divider and the operations of addition and subtraction are determined by the type of single sideband mixer and pulse incrementor utilized. To suppress spurious output signals, both control frequencies f d and f s are maintained substantially above the phase-locked loop cutoff frequency.