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Urtc1000 Driver Windows 7 64 Bit

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Urtc1000 Driver Windows 7 64 Bit

The use of a fractional-N frequency synthesizer (FS) typically provides greater accuracy than analog voltage-controlled oscillators (VCOs). However, an FS can require many phase detectors, and a coarse sample of the phase error can be made before the next round of feedback occurs. The resulting fractional-N performance of a frequency-locked loop (FLL) can degrade as the loop bandwidth is increased whereby the FLL is in transition from the phase-locked state to the free-running state. This eventually leads to the loss of lock and the reduced-gain conditions can cause the loop to vibrate or even lose lock entirely. To solve this problem, a controlled phase error (CPE) approach is generally adopted. The phase error is manually adjusted by the user to achieve phase lock and then fixed in value (or alternatively, the loop automatically switches back and forth between the CPE and fractional-N modes). For some applications, this is acceptable although not optimal. The transmission of user data generally requires instantaneous, and uninterrupted lock. Arbitrary operation of the PLL in either mode will increase the data jitter since the user data will be influenced by the PLL's noise excursions. A practical alternative is to have dedicated signals with a constant phase and a constant frequency.

"In 1971, the IEEE GLOBECOM technical symposium paper described the need for a practical PLL design using fractional-N technology. A PLL with a single low-noise charge-pump driver was described along with a VCO whose output could be scaled to the needed frequency by the feedback divider. Induced phase error was used to generate a phase-locked loop control voltage to force the VCO to oscillate. The trial VCO and PLL were tested in laboratory conditions and the phase-locked loop was demonstrated."2

With the introduction of time-domain signal processing in the late 1970s, the CPE based PLLs were utilized to provide optimal signal-to-noise ratio (SNR). As the name CPE suggests, the CPE error is continuously fed back to the VCO and is calculated in the time-domain. d2c66b5586


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