| 摘要 |
<p>A process variable transmitter, implemented in a dual PLL structure, includes a first PLL having a first bandwidth producing a first output signal, and a second PLL having a second bandwidth narrower than the first bandwidth of the first PLL. The first and second PLLs are operable to lock into a frequency of an input signal and produce first and second output signals, respectively. The second PLL is operable to lock into the frequency of the input signal with greater accuracy and greater immunity to noise than the first PLL. A switch is operable to switch an output signal of the process variable transmitter between the first output signal and the second output signal.</p> |
