Receiver Mixer Harmonic Selection for Dynamic RF Gain Control
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Solution Overview
Problem
Direct-conversion RF receivers face challenges in managing signal gain effectively, leading to energy inefficiency and battery drainage due to high sensitivity, which results in receiver overload for strong signals and reduced sensitivity for weak signals.
Innovation Solution
The system adjusts signal gain by selecting harmonics for mixing RF signals with a local oscillator signal, reducing the local oscillator frequency to lower the mixer gain for strong signals and increasing it for weak signals, based on measured signal strength, to optimize energy usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the receiver uses high sensitivity circuitry to detect weak signals, then signal detection accuracy is improved, but the receiver becomes prone to overload when receiving strong signals
Solution Approach 1:
The patent implements dynamic gain adjustment by selecting different harmonics of the local oscillator signal based on the strength of the received RF signal. The system transitions from a static gain configuration to a dynamic one where the mixer gain is adjusted in real-time: for weak signals, higher harmonics provide higher gain to improve detection accuracy, while for strong signals, lower harmonics provide lower gain to prevent overload. This dynamic adaptation resolves the contradiction between sensitivity and overload resistance.
Solution Approach 2:
The patent changes the operating parameters of the mixer by selecting different harmonic orders (n=1, 3, 5, ...) of the local oscillator signal. Each harmonic provides a different conversion gain, allowing the system to adjust the mixer gain parameter dynamically. By changing the harmonic order parameter based on signal strength measurements, the system can optimize performance for both weak and strong signals, resolving the contradiction between detection accuracy and overload resistance.
2Reliability
If the receiver performs signal gain reductions for strong signals, then receiver overload is prevented, but energy consumption increases leading to battery drainage
Solution Approach 1:
The patent converts the typically unwanted harmonic components of the local oscillator signal into a useful resource for gain control. Instead of filtering out higher harmonics as noise or interference, the system deliberately uses them as the local oscillator signal to achieve natural gain reduction. This approach prevents overload while avoiding the need for additional active gain control circuits that would consume extra power, thus converting a potential harm (harmonic content) into a benefit (power-efficient gain control).
Solution Approach 2:
The system uses the inherent properties of the local oscillator signal (its harmonic content) to automatically regulate the mixer gain. The harmonic selection mechanism allows the system to self-adjust its gain based on the received signal strength without requiring external power-hungry amplification or attenuation circuits. The local oscillator signal itself serves the dual purpose of frequency conversion and gain control, eliminating the need for separate power-consuming gain control stages.
3Use of energy by moving object
If the local oscillator frequency is reduced to lower mixer gain, then power consumption is reduced, but the ability to handle weak signals deteriorates
Solution Approach 1:
The patent implements a dynamic harmonic selection mechanism that adapts the local oscillator harmonic order based on the strength of the received signal. For weak signals, the system selects higher harmonics (n=3, 5, ...) which provide higher mixer gain to ensure adequate signal strength for accurate detection. For strong signals, it selects lower harmonics (n=1, 3, ...) which provide lower gain and correspond to lower power consumption. This dynamic adaptation allows the system to optimize both power consumption and weak signal detection capability under different operating conditions.
Solution Approach 2:
The system changes the harmonic order parameter of the local oscillator signal based on received signal strength measurements. By adjusting this parameter, the mixer gain is changed accordingly: higher harmonics provide higher gain for weak signals, while lower harmonics provide lower gain for strong signals. This parameter change enables the system to maintain weak signal detection capability when needed while reducing power consumption when possible.
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 reduces power consumption and battery drainage by dynamically adjusting the mixer gain, allowing efficient handling of both strong and weak signals, thereby extending device battery life.
Implementation Method 1
mixing a received radio frequency (RF) signal with a local oscillator signal to generate an output signal
Implementation Method 2
filtering the output signal to select a filtered output signal
Data Source
AI summary
A method of harmonic selection for mixing with a received signal includes receiving a radio frequency (RF) signal and determining a variable gain setting from among a plurality of gain settings or from a range of gain settings. The variable gain setting is based on the RF signal. The method further includes selecting a harmonic to provide to an input of a mixer to generate an output signal. A baseband signal or an intermediate frequency signal is generated from the output signal. The harmonic is selected based on the variable gain setting. An apparatus includes a harmonic selector that is configured to generate an indication of a selected harmonic. The harmonic is selected based on a variable gain setting determined from among a plurality of gain settings or from a range of gain settings. Based on the selected harmonic, a mixer generates an output signal. A baseband signal or an intermediate signal is generated from the output signal.