Fast coarse tune and fine tune calibration for a synthesizer by multi-curve calibration within a target window
US9954543B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 8, 2017 |
| Grant date | Apr 24, 2018 |
| Priority date | — |
| Expiry date | Feb 8, 2037 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03L2207/06
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A Phase-Locked Loop (PLL) has a multi-curve voltage-controlled oscillator (VCO) with a curve-select input that adjusts the capacitance within the VCO and thus the VCO gain. A calibration unit generates a curve-select value to the VCO. Coarse calibration selects a Center Curve CC value using binary search of the curve-select bits. During fine calibration, the number of pulses of the VCO output are counted and stored for all curves in a target window around the center curve. The stored pulse counts are compared to an ideal pulse count for a specified frequency, and the curve-select value for the closest-matching pulse count is applied to the VCO. The target window is much smaller than all possible curves, so calibration is performed only on a few curves, reducing calibration time. A switch before the VCO opens the loop for faster open-loop calibration. Pulses are counted digitally without expensive analog comparators.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.