Reactive Gain-Control Stage for Low-Noise Receiver Tuning
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Solution Overview
Problem
Conventional receivers face challenges in maintaining optimal signal-to-noise ratio under varying reception conditions, such as weak or strong signal strengths, which can lead to noise degradation, overload, and spurious signals, especially when receiving radiofrequency spectra with mixed signal strengths.
Innovation Solution
A gain-controllable stage comprising a reactive signal divider and an amplifier arrangement, where the signal division factor is adjusted based on the frequency and signal strength, allowing for noise matching and impedance transformation to minimize noise across a frequency band, thereby improving reception quality without complex filter structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a filter is placed in front of the gain-controllable stage to attenuate strong signals, then spurious signals are reduced, but the source impedance varies throughout the frequency band causing increased noise under weak signal conditions
Solution Approach 1:
The patent applies dynamics by making the signal division factor adjustable based on reception conditions. The reactive signal divider's division factor is dynamically changed according to signal strength indications, allowing the system to adapt between weak and strong signal conditions rather than using a fixed filter structure.
Solution Approach 2:
The patent changes the parameter of signal division factor in the reactive signal divider based on reception conditions. By adjusting this parameter according to signal strength, the system optimizes both spurious signal reduction and noise performance without requiring complex variable impedance filters.
2Reliability
If the gain-controllable stage provides high gain under weak signal conditions, then signal-to-noise ratio is improved, but the stage may become overloaded under strong signal conditions causing distortion
Solution Approach 1:
The gain of the amplifier arrangement is dynamically controlled by adjusting the signal division factor of the reactive signal divider based on signal strength indications. This allows the system to provide high gain when needed while preventing overload through automatic gain control.
Solution Approach 2:
The system uses signal strength indications as feedback to control the gain of the amplifier arrangement. The controller adjusts the signal division factor based on the received signal strength, creating a closed-loop control system that prevents both noise degradation and overload distortion.
3Object-generated harmful factors
If a tuned filter is used to pass weak desired signals and attenuate strong interfering signals, then spurious signal generation is reduced, but the source impedance variation causes the gain-controllable stage to produce more noise throughout most of the frequency band
Solution Approach 1:
Instead of using a tuned filter with fixed impedance characteristics, the patent changes the signal division parameter of the reactive signal divider based on reception conditions. This allows optimization of both spurious signal reduction and noise performance by adapting the division factor rather than relying on fixed filter impedance.
Solution Approach 2:
The reactive signal divider serves multiple functions: it acts as both a signal division element and an impedance transformation element. By adjusting its division factor, it can optimize performance for both weak and strong signal conditions without requiring separate specialized circuits.
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 solution enables better reception quality by dynamically controlling gain to prevent noise degradation and overload, maintaining a low noise level across a wide frequency band, thus enhancing the overall performance of the receiver under diverse reception conditions.
Implementation Method 1
The reactive signal divider may be a capacitive signal divider or an inductive signal divider, or a combination of those
Data Source
AI summary
A gain-controllable stage (CLN, A1, A2 . . . , A7, ACC) comprises a reactive signal divider (CLN) followed by an amplifier arrangement (A1, A2 . . . , A7, ACC). The reactive signal divider (CLN) may be in the form of, for example, a capacitive ladder network. The gain-controllable stage (CLN, A1, A2 . . . , A7, ACC) has a gain factor that depends on a signal division factor that the reactive signal divider (CLN) provides. The reactive signal divider (CLN) forms part of a filter (LC). The signal division factor is adjusted on the basis of a frequency (F) to which the receiver is tuned and a signal-strength indication (RS).