Fast Filter Calibration Using Stored Bandwidth Codes
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Solution Overview
Problem
Receiver filters in mobile devices face performance variations due to process, voltage, and temperature (PVT) changes, leading to shifts in bandwidth, which affect the quality of baseband signals and require calibration to maintain high performance.
Innovation Solution
A fast filter calibration system comprising a multi clock system, switch unit, filter unit, auto calibration apparatus, and fast calibration apparatus that generates calibration signals and adjusts bandwidth using a bandwidth code (BWC) to quickly fine-tune filter settings, ensuring optimal performance under varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional calibration process is used to compensate for PVT variations, then filter bandwidth can be fine-tuned, but calibration time and resource consumption increase
Solution Approach 1:
The patent pre-calculates and stores optimal bandwidth control values in a lookup table during the manufacturing process, mapping expected PVT conditions to corresponding calibration parameters. During operation, the system simply queries this pre-prepared table based on measured PVT values, eliminating the need for time-consuming iterative calibration while maintaining accurate bandwidth compensation
Solution Approach 2:
The patent replaces traditional iterative mechanical calibration processes with a computational approach using a lookup table and direct parameter retrieval. Instead of physically adjusting filter components through repeated measurement and adjustment cycles, the system uses pre-computed data structures and algorithmic lookups to achieve the same calibration effect instantaneously
2Reliability
If filter bandwidth is adjusted to compensate for PVT variations, then baseband signal quality is maintained, but device complexity increases
Solution Approach 1:
The patent extracts the complex calibration computation from the operational system and relocates it to the manufacturing/testing phase. The lookup table containing all necessary calibration data is pre-populated and stored in compact form, allowing the runtime system to use only simple table lookup and parameter application operations, thereby maintaining signal quality without adding operational complexity
Solution Approach 2:
All complex calibration computations are performed in advance during manufacturing, with results stored in a compact lookup table. This preliminary action transfers the computational burden from the field-operational phase to the manufacturing phase, simplifying the deployed device while maintaining calibration accuracy
Data Source
AI summary
A fast filter calibration system includes a multi clock generator, an analog filter including a variable capacitor and a fast calibration apparatus. The fast calibration apparatus further includes a phase comparator, a frequency detector and a fast calibration unit. The fast calibration unit stores a binary code corresponding to a bandwidth frequency of a filter and initiates a fast filter calibration by calibrating the filter from a binary code close to a guaranteed-by-design binary code for the bandwidth frequency to be calibrated.