Low-IF Receiver Power Management via Dynamic Mixer Control
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Solution Overview
Problem
Low intermediate frequency (low-IF) receivers face high current consumption due to two independent analog/RF circuit paths for in-phase and quadrature signal representations, which is particularly problematic for battery-operated devices aiming to prolong battery life.
Innovation Solution
A receiver design that includes a controller to determine when interference is below a threshold, allowing it to power off one of the in-phase or quadrature mixers, switching to a real analog signal representation and using a low pass filter to suppress images, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two independent analog/RF circuit paths are used for in-phase and quadrature signal representations, then signal processing capability is improved, but current consumption increases
Solution Approach 1:
The patent applies dynamics by making the receiver's circuit configuration changeable over time. The controller dynamically switches between two operational modes: a complex mode using both in-phase and quadrature circuit paths when interference is detected, and a real mode using only one circuit path when the environment is clean. This dynamic reconfiguration allows the system to adapt its signal processing capability and power consumption to current operating conditions, resolving the contradiction between maintaining high signal processing capability and reducing current consumption.
Solution Approach 2:
The patent applies parameter changes by modifying the operational state of the receiver's circuit paths based on detected interference levels. The controller monitors the radio frequency environment and changes the operational parameters (number of active circuit paths) accordingly. When interference is below a threshold, the system transitions from using two independent analog/RF circuit paths to using one path, thereby changing the system's power consumption parameter while maintaining adequate signal processing capability.
2Duration of action of moving object
If one mixer is powered off to reduce power consumption, then battery life is prolonged, but interference rejection capability may be degraded
Solution Approach 1:
The patent applies feedback by implementing a closed-loop control system where the controller continuously monitors the radio frequency environment for interference signals. Based on this feedback information, the controller makes informed decisions about whether to operate in complex mode (both mixers active) or real mode (one mixer active). This feedback mechanism ensures that the system maintains adequate interference rejection capability by switching to the appropriate mode based on actual environmental conditions, thereby prolonging battery life without compromising reliability when unnecessary.
3Use of energy by moving object
If a low pass filter is used to suppress images when operating in real mode, then power consumption is reduced, but filter complexity is added
Solution Approach 1:
The patent applies partial action by implementing a low pass filter that selectively suppresses only the image frequencies that occur when operating in real mode, while leaving the desired signal frequencies unaffected. The filter is designed with specific cutoff characteristics that remove the harmful image components (at ±2×the offset frequency) while preserving the wanted signals. This partial filtering approach addresses the specific problem caused by real mode operation without unnecessarily complicating the overall receiver design.
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 effectively prolongs battery life in low-IF receivers while maintaining communication functionality by reducing power usage when operating in clean environments.
Implementation Method 1
an output signal from the complex mixer is provided to a low pass filter. The low pass filter suppresses images
Data Source
AI summary
A receiver includes a first local oscillator, and an in-phase mixer and a quadrature mixer coupled to the first local oscillator and configured to generate in-phase and quadrature signals based upon received RF signals. A complex mixer is downstream from the in-phase and quadrature mixers. A controller is coupled to the in-phase and quadrature mixers and is configured to determine when the in-phase and quadrature signals include interference less than an interference threshold, and then powers off one of the in-phase and quadrature mixers.