Tunable LNA Tracking Filter Calibration Without Dummy LC Filters
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Solution Overview
Problem
Existing broadband television receivers face challenges in tuning integrated LC filters due to interference from the antenna, leading to increased die area and radiation of calibration signals, which necessitates duplicating tunable filters and limiting power consumption.
Innovation Solution
A method involving a tunable Low Noise Amplifier (LNA) with integrated LC loads, where a local oscillation signal is used to select and adjust the LC load capacitance during calibration, allowing for in-signal-path tuning and minimizing interference and radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a dummy tunable filter is duplicated and tuned separately from the main signal path, then calibration can be performed without antenna interference, but the die area increases unnecessarily
Solution Approach 1:
The patent merges the calibration function directly into the main signal path by using the same tunable filter that will be used for signal processing. The filter is calibrated in-place during manufacturing without requiring a separate dummy filter, thereby eliminating the additional die area while maintaining calibration accuracy through controlled signal injection.
Solution Approach 2:
The patent performs preliminary calibration action during the manufacturing process by injecting a calibration signal through the antenna before the receiver is deployed. This preliminary tuning establishes the correct filter characteristics in advance, eliminating the need for post-manufacturing calibration or separate dummy filters.
2Measurement precision
If the entire receiver path including down-mixers is configured to receive the filtered signal during calibration, then complete signal path testing is achieved, but power consumption increases
Solution Approach 1:
The patent applies partial action by selectively enabling only the necessary components during calibration - specifically the tunable filter and the signal path up to the power detector. Components that are not needed for filter calibration, such as down-mixers and baseband processing, remain disabled, thereby reducing power consumption while maintaining sufficient measurement accuracy for filter tuning.
3Reliability
If AGC is used to achieve high linearity in the presence of in-band blockers, then receiver linearity improves, but the receiver noise figure increases due to gain reduction
Solution Approach 1:
The patent extracts the tracking filter function from the conventional receiver architecture and integrates it directly into the LNA stage. This extraction allows the filter to operate independently before the signal enters the main gain stages, enabling high linearity performance without requiring aggressive AGC gain reduction that would otherwise increase the noise figure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient tuning of integrated tracking filters within the receiver, reducing interference and radiation, and allowing for direct calibration within the signal path, thereby minimizing power consumption and die area.
Implementation Method 1
a tunable Low Noise Amplifier (LNA) having a plurality of LNAs and a plurality of LC loads coupled to the plurality of LNAs
Implementation Method 2
The frequency response of a filter refers to the characteristic(s) of the filter that conditions the input/internal signal to the filter
Data Source
AI summary
A method of tuning a receiver includes: providing a tunable Low Noise Amplifier (LNA) having a plurality of LNAs and a plurality of LC loads coupled to the plurality of LNAs; selecting a desired LNA and a LC load corresponding to the desired LNA; isolating the desired LNA from the selected LC load; generating a local oscillation (LO) signal; routing the LO signal to the output of the tunable LNA to generate a filtered LO signal; determining a first signal power level of the filtered LO signal; changing the capacitance in the selected LC load and determining a second signal power level of the filtered LO signal; comparing the first filtered signal power level to the second filtered signal power level; and according to the comparison result, determining whether or not to adjust the capacitance in the selected LC load.