Frequency Locked Loop Supply Adjustment for Faster Lock Time
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Solution Overview
Problem
Frequency locked loops (FLLs) face calibration challenges due to temperature drift, leading to increased lock times and undesirable jitter, as existing methods require coarse and fine band adjustments, which are time-consuming and power-intensive.
Innovation Solution
A fast voltage and frequency adjustment apparatus using a capacitor-less low dropout regulator and Gray code counters to adjust the supply to the oscillator, allowing for precise frequency determination without banding, thereby reducing lock time and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If coarse and fine band adjustments are used to achieve frequency range and resolution, then frequency accuracy is improved, but lock time increases and power consumption increases
Solution Approach 1:
The frequency adjustment range is divided into multiple bands (first band, second band, third band) with different resolutions. Each band provides a specific frequency range with optimized resolution, allowing the system to achieve high frequency accuracy without requiring exhaustive coarse-fine searches across the entire range. The segmentation enables the FLL to operate in the most appropriate resolution band, significantly reducing lock time while maintaining frequency precision.
Solution Approach 2:
The system dynamically switches between different frequency adjustment bands based on operating conditions. The FLL can transition between first band mode (coarse adjustment), second band mode (fine adjustment), and third band mode (very fine adjustment) as needed. This dynamic adaptation allows the system to optimize between lock time and frequency accuracy in real-time, avoiding the fixed trade-off of traditional coarse-fine architectures.
2Measurement precision
If coarse and fine band adjustments are used to achieve frequency range and resolution, then frequency accuracy is improved, but power consumption increases
Solution Approach 1:
The frequency adjustment is segmented into multiple bands with different power consumption characteristics. The system can select the appropriate band based on the required frequency accuracy, avoiding the need to continuously operate high-precision fine adjustment circuits when coarse adjustment suffices. This segmentation enables power-efficient operation by activating only the necessary adjustment precision level.
Solution Approach 2:
The system changes operational parameters by switching between different frequency adjustment bands. Each band has optimized parameters for its specific frequency range and resolution requirements. By adjusting which band is active, the system can optimize power consumption while maintaining the required frequency accuracy, avoiding unnecessary power expenditure on high-resolution adjustments when lower resolution is sufficient.
3Stability of the object's composition
If frequency change due to temperature drift is accounted for using adequate fine code range, then frequency stability is improved, but lock time increases
Solution Approach 1:
The system segments temperature compensation into specific bands rather than relying entirely on extended fine code ranges. The first band handles coarse frequency adjustments including major temperature drift compensation, while subsequent bands provide finer adjustments. This segmentation allows temperature stability to be achieved without requiring the FLL to search through excessive fine code values, thereby reducing lock time while maintaining frequency stability.
Solution Approach 2:
The system performs preliminary frequency adjustments in the first band to account for temperature drift before entering fine adjustment bands. By addressing temperature compensation early in the locking process through coarse band adjustments, the system reduces the burden on fine code ranges and accelerates the overall locking process, achieving frequency stability without prolonged lock times.
4Stability of the object's composition
If frequency change due to temperature drift is accounted for by jumping coarse bands, then frequency stability is improved, but output jitter increases
Solution Approach 1:
The frequency adjustment is segmented into multiple bands that provide a smooth transition path for temperature compensation. Instead of jumping between distant coarse bands, the system progresses through adjacent bands (first band to second band to third band) with overlapping frequency ranges. This segmented approach eliminates abrupt frequency transitions and associated jitter, providing smooth frequency stability during temperature drift compensation.
Solution Approach 2:
The system dynamically selects the appropriate band and adjustment step size based on the current frequency error and temperature drift magnitude. For small drifts, the system makes fine adjustments within the current band; for larger drifts, it progressively transitions through adjacent bands. This dynamic, adaptive approach replaces the static coarse-band jumping method, eliminating output jitter while maintaining frequency stability during temperature compensation.
Data Source
AI summary
An apparatus is provided which comprises: a frequency locked loop (FLL) comprising an oscillator including a plurality of delay stages, wherein an output of each delay stage is counted to determine a frequency of the FLL; and one or more circuitries coupled to the FLL to adjust a power supply to the FLL according to the determined frequency of the FLL.