Integrated Channel Filter for Broadband Tuner Intermodulation Control
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Solution Overview
Problem
Broadband tuners processing over one-hundred channels experience significant noise and reduced gain programmability due to increased intermodulation products, which degrade signal quality and increase power consumption.
Innovation Solution
An integrated channel filter system formed on an integrated circuit that attenuates approximately 80% of undesired channels before processing, reducing intermodulation products by 95% and increasing gain programmability by selecting and dissipating unwanted channels in lossy components, thereby reducing the number of channels processed by the tuner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a broadband tuner processes over one-hundred channels, then the tuner can receive and process a wide range of channels, but the number of intermodulation products grows as the square of the number of channels, resulting in significant noise and reduced gain programmability
Solution Approach 1:
The patent applies preliminary action by placing a filter before the tuner to pre-process the input signal and remove unwanted channels before they enter the tuner. This filter attenuates approximately 80% of undesired channels in advance, preventing them from generating intermodulation products within the tuner. The filter is configured with multiple switchable bands that can be selectively activated based on the desired channel range, thereby reducing the channel count presented to the tuner and eliminating the square-law growth of intermodulation products.
2Adaptability or versatility
If a broadband tuner processes over one-hundred channels, then the tuner maintains wide channel coverage, but the intermodulation products decrease the range of gain programmability of the tuner
Solution Approach 1:
The filter performs preliminary channel selection and attenuation before the signal reaches the tuner, reducing the number of active channels from over one-hundred to a manageable subset. This preliminary action clears the signal path of interfering channels, allowing the tuner's gain control to operate over a wider effective range without being constrained by the presence of numerous strong unwanted signals that would otherwise limit gain adjustment capabilities.
3Ease of manufacture
If a filter is not formed on the integrated circuit, then the filter can be implemented with discrete components, but the undesired channels are reflected back to the transmitter or source, corrupting all channels including desired channels
Solution Approach 1:
The patent merges the filter with the tuner into a single integrated circuit device. The filter is formed using integrated circuit components including capacitors, inductors, and switches fabricated on the same semiconductor substrate as the tuner. This integration ensures that the filter's output is directly coupled to the tuner's input without external connections that could cause reflections. The integrated structure dissipates reflected energy within the circuit rather than allowing it to bounce back to the transmitter, thereby preventing signal corruption while maintaining manufacturing efficiency through single-chip fabrication.
4Object-generated harmful factors
If the number of channels processed by the tuner is reduced, then intermodulation products are reduced, but the filter must be configured to selectively attenuate specific channel bands
Solution Approach 1:
The filter incorporates dynamic switching capability with multiple switchable capacitor banks that can be selectively connected or disconnected based on the desired channel band. The filter is divided into multiple bands (e.g., first band, second band, third band) with associated switches that allow the filter's frequency response to be dynamically adjusted. This dynamic configuration enables the filter to adapt to different channel selection scenarios, reducing intermodulation products for various desired channels while maintaining a compact integrated structure. The switching elements are controlled by logic circuitry that automatically selects the appropriate filter configuration based on the desired channel input.
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
The integrated filter system significantly reduces intermodulation products and second-order harmonic distortion, enhancing signal quality and reducing power consumption in subsequent stages of the tuner.
Implementation Method 1
The filter which is formed on the integrated circuit communicates the desired channels but does not reflect the undesired channels back to the transmitter or source of the input signal. Instead, the undesired channels are dissipated in various components, such as the lossy elements, of the integrated circuit.
Implementation Method 2
The filter comprises at least one stage that comprises an inductor, a first capacitor, and a plurality of switchable capacitors
Implementation Method 3
The filter comprises at least one stage that comprises an inductor, a first capacitor, and a plurality of switchable capacitors
Data Source
AI summary
A system includes a filter and a tuner formed on an integrated circuit. The filter receives an input signal comprising a first number of channels and communicates an intermediate output signal comprising a second number of channels less than the first number of channels. The tuner is coupled to the filter and receives the intermediate output signal and communicates an output signal comprising a third number of channels less than the second number of channels.