Low-IF Receiver Branch Switching for Image-Aware Power Reduction
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Solution Overview
Problem
Current radio frequency (RF) communication circuits, particularly low intermediate frequency (LIF) receivers, face challenges in power consumption due to high image rejection ratio requirements, which are not always necessary as image signal strength varies, leading to inefficient power usage.
Innovation Solution
An image-aware single-branch quadrature RF downconversion (SQRD) low IF receiver is developed, which monitors image strength and switches to single-branch operation when it is low, reducing power consumption by shutting off unnecessary components like the local RF oscillator circuitry, RF mixers, and analog-to-digital converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If high image rejection ratio is maintained in LIF receiver, then image interference is suppressed, but power consumption increases
Solution Approach 1:
The receiver dynamically switches between DQRD and SQRD modes based on real-time image signal strength detection. When image interference is high, the system operates in DQRD mode with full image rejection capability. When image interference is low, the system switches to SQRD mode to reduce power consumption, thus adapting the image rejection level to actual channel conditions rather than maintaining a fixed high rejection ratio
Solution Approach 2:
The system changes the operational parameters of the receiver by switching between two distinct modes: DQRD mode with high image rejection ratio for strong image signals, and SQRD mode with reduced image rejection for weak image signals. This parameter change allows the receiver to optimize the trade-off between image rejection performance and power consumption based on channel conditions
2Object-affected harmful factors
If dual-branch quadrature downconversion is used, then image rejection capability is improved, but device complexity increases
Solution Approach 1:
The invention extracts and removes the Q-branch components (Q mixer, Q low-pass filter, and associated local oscillator circuitry) when image interference is weak, operating in SQRD mode with only the I-branch. This extraction of unnecessary components reduces device complexity and power consumption while maintaining adequate performance when image rejection is not critical
3Reliability
If all receiver components are always active, then reception reliability is maintained, but power consumption increases
Solution Approach 1:
The system periodically monitors image signal strength and switches between operational modes accordingly. By using periodic detection of image interference levels and switching between DQRD and SQRD modes, the system maintains reception reliability when needed while reducing power consumption during periods of low image interference, rather than keeping all components continuously active
Data Source
AI summary
A novel and useful apparatus and method for an image-interferer aware single quadrature RF downconversion (SQRD) low intermediate frequency (LIF) receiver and related power reduction techniques utilized therein. The invention applies zero-margin adaptive transceiver (ZMAT) design principles to considerably reduce the receiver's power consumption in an adaptive fashion in accordance with the instantaneous reception conditions. In a low IF dual-branch (i.e. quadrature) downconversion receiver, the radio monitors the image strength and shuts off the receiver's Q branch (or I branch) when image rejection is not needed (i.e. when the relative image strength is below a threshold), thus significantly reducing power consumption in the RF receiver. A zero IF receiver is switched to a SQRD low IF receiver of lower power consumption when the image interferer strength is low enough to allow for a given required level of performance.