Communication Apparatus Calibration Using Reconfigurable Filter
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Solution Overview
Problem
Existing calibration methods for analogue circuits in communication systems are limited by PVT variations, non-ideal transistor characteristics, and limited voltage headroom, leading to high power consumption and complexity, especially when measuring system response within the normal operating frequency range.
Innovation Solution
A communication apparatus and method that allows for a second mode of operation where a signal with higher frequency range is used for calibration, inhibiting transmission to avoid unwanted emissions, and employing a filter stage configurable between low-pass and high-pass transfer functions to facilitate precise measurement of analogue circuitry variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If calibration is performed using baseband signals within the normal operating frequency range, then measurement precision within this range is improved, but device complexity and manufacturing cost increase due to the need for precise measurement and handling of signals in this sensitive frequency range
Solution Approach 1:
The patent changes the frequency parameter of the calibration signal from the normal operating range to a higher frequency range. This parameter change allows calibration to be performed at frequencies where the system response is less sensitive and easier to measure, thereby reducing device complexity while maintaining measurement precision through the use of higher frequency test signals
2Measurement precision
If calibration signals with higher frequency energy are used, then calibration precision across a wider frequency range is improved, but unwanted emissions may occur if transmission is not inhibited
Solution Approach 1:
The patent implements dynamic switching of the coupling stage between two states: a first state that couples the processed signal to the output for transmission during normal operation, and a second state that inhibits transmission during calibration. This dynamic reconfiguration allows the system to use higher frequency calibration signals for improved precision while preventing unwanted emissions by blocking the signal path to the output during calibration mode
3Reliability
If a filter stage is configured to pass higher frequencies during calibration, then calibration effectiveness is improved, but the filter must be reconfigurable between different transfer functions increasing device complexity
Solution Approach 1:
The filter stage is designed with multi-functionality to serve dual purposes: during normal operation, it operates as a low-pass filter to pass the operating frequency range and block higher frequencies; during calibration, it is reconfigured as a high-pass filter to pass the higher frequency calibration signals. This universal design allows a single filter stage to perform multiple functions, improving calibration effectiveness while minimizing the increase in device complexity by using the existing filter infrastructure for both operational modes
Data Source
AI summary
A communication apparatus (200) has a calibration mode in which a signal is passed through circuitry (30, 80) of the apparatus, and a controller (160) measures the response of the circuitry (30, 80) to the signal and adjusts the circuitry (30, 80) to improve performance. The signal used for calibration has a wider bandwidth than the bandwidth of signals used for transmission. The wider bandwidth may be provided by reconfiguring a digital filter (20) from low-pass to high-pass.