Method and apparatus to achieve a process, temperature and divider modulus independent PLL loop bandwidth and damping factor using open-loop calibration techniques
US7095287B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 28, 2004 |
| Grant date | Aug 22, 2006 |
| Priority date | — |
| Expiry date | Jan 28, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L2207/04
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
Several open-loop calibration techniques for phase-locked-loop circuits (PLL) that provide a process, temperature and divider modulus independence for the loop bandwidth and damping factor are disclosed. Two categories of open-loop techniques are presented. The first method uses only a single measurement of the output frequency from the oscillator and adjusts a single PLL loop element that performs a simultaneous calibration of both the loop bandwidth and damping factor. The output frequency is measured for a given value of the oscillator control signal and the charge-pump current is adjusted such that it cancels the process variation of the oscillator gain. The second method uses two separate and orthogonal calibration steps, both of them based on the measurement of the output frequency from the oscillator when a known excitation is applied to the open loop signal path. In the first step the loop bandwidth is calibrated by adjusting the charge-pump current based on the measurement of the forward path gain when applying a constant phase shift between the two clocks that go to the phase frequency detector, while the integral path is hold to a constant value. During the second step t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.