Multi-Clock Filter Auto-Calibration for Low-Noise Frequency Tuning
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing clock generator methods for filter auto-calibration in receiver applications face issues such as noise in clock signals, high current consumption, large chip area usage, and increased mass testing costs due to Process, Voltage, and/or Temperature (PVT) variations.
Innovation Solution
A filter auto-calibration system utilizing a multi-clock generator with a Sigma-Delta fractional-N frequency synthesizer and a multi-modulus divider, which generates a variable frequency signal independent of the crystal frequency, allowing for flexible frequency adjustment and reduced PVT variations, thereby enabling accurate filter calibration with reduced testing time and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional clock generator is used for filter auto-calibration, then the filter calibration can be performed, but noise in the generated clock signal occurs and current consumption increases
Solution Approach 1:
The clock signal generation is divided into multiple independent oscillators operating at different frequencies (e.g., 1.024 MHz, 2.048 MHz, 4.096 MHz, 8.192 MHz). Instead of using a single clock generator that produces noise, the system segments the frequency generation across multiple clean oscillators and selects the appropriate one based on the desired output frequency, thereby reducing noise in the generated clock signal.
Solution Approach 2:
The system changes the operating parameters by using multiple oscillators with fixed, precisely controlled frequencies rather than a single variable-frequency oscillator. This allows the system to switch between clean, stable frequency sources depending on the calibration requirements, improving signal quality while maintaining calibration accuracy.
2Measurement precision
If a traditional clock generator is used for filter auto-calibration, then the filter calibration can be performed, but chip area usage increases
Solution Approach 1:
The multi-clock generator system serves multiple functions: it provides clock signals for filter auto-calibration, generates frequency signals for the Sigma-Delta fractional-N frequency synthesizer, and supplies timing signals for various system operations. By making the clock generation system universal, the patent reduces the need for separate dedicated circuits, thereby reducing overall chip area usage while maintaining calibration accuracy.
Solution Approach 2:
The patent combines multiple oscillator circuits and frequency division functionality into a single integrated multi-clock generator module. This merging of functions (frequency generation, frequency division, and clock distribution) into one unified system reduces the total chip area required compared to having separate dedicated circuits for each function.
3Adaptability or versatility
If frequency adjustment is made flexible, then adaptability improves, but PVT variations increase mass testing cost
Solution Approach 1:
The system performs preliminary frequency calibration and characterization during manufacturing for each oscillator. The measured frequency values are stored in lookup tables or calibration data structures. During operation, the system retrieves pre-calibrated frequency values corresponding to different temperature and process conditions, eliminating the need for expensive real-time testing and adaptation, thus reducing mass testing costs while maintaining frequency accuracy.
Solution Approach 2:
The system incorporates feedback mechanisms where the actual output frequency is monitored and compared against target values. Based on this feedback, the system adjusts selection of oscillators and division ratios to compensate for PVT variations. This closed-loop approach enables flexible frequency adjustment while automatically compensating for manufacturing variations, reducing the need for expensive individual testing and calibration.
Data Source
AI summary
A filter auto-calibration system includes a multi-clock module. The multi-clock module includes a multi-clock generator that is configured to generate a clock signal with a variable frequency based on a channel setting. There is at least one filter to be calibrated. An auto-calibration control module is configured to control calibration of the at least one filter based on the channel setting. The multi-clock module is configured to supply the variable frequency clock signal to the at least one filter and to the auto-calibration control module, and the at least one filter is coupled to the auto-calibration control module.