Single-LO Receiver Gain Compensation for Multi-Carrier SQNR
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Solution Overview
Problem
Existing receivers using a single local oscillator (LO) face challenges in maintaining signal quality and preventing signal saturation when handling multiple cells with varying signal strengths, particularly in wide bandwidth applications like millimeter wave, due to inconsistent analog and digital gain settings.
Innovation Solution
A digital signal processing circuit with an analog gain compensator, ADC, and multiple filtering circuits that compensate for analog and digital gains separately for each component carrier, followed by decimation, to maintain signal-to-quantization noise ratio (SQNR) and prevent saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a common analog gain is set to a cell having relatively strong signal strength, then power saturation is prevented in strong cells, but relatively weak cell signals exhibit a low signal-to-quantization noise ratio
Solution Approach 1:
The patent divides the gain compensation function into separate analog and digital gain compensators, each handling different signal strength ranges. The analog gain compensator processes strong signals before ADC to prevent saturation, while the digital gain compensator processes weak signals after ADC to improve SQNR. This segmentation allows independent optimization for different signal conditions without mutual interference.
Solution Approach 2:
The patent implements dynamic gain control where the analog and digital gain compensators are selectively activated based on the received signal strength. The control circuit dynamically adjusts which compensator is used for each cell signal, enabling adaptive optimization of both saturation prevention and SQNR improvement across varying signal conditions.
2Reliability
If a common analog gain is set to a cell having relatively weak signal strength, then signal-to-quantization noise ratio is improved for weak cells, but power saturation occurs in relatively strong cell signals
Solution Approach 1:
The patent segments the signal processing chain into two parallel paths: an analog gain compensation path for strong signals and a digital gain compensation path for weak signals. This segmentation enables the system to apply appropriate gain control to each signal type, preventing saturation in strong signals while improving SQNR in weak signals without compromising either.
Solution Approach 2:
The patent applies different gain compensation strategies to different signal strength regions. The analog gain compensator with higher gain is applied locally to strong signals before quantization, while the digital gain compensator with lower gain is applied locally to weak signals after quantization. This local quality approach optimizes performance for each specific signal condition.
3Reliability
If separate analog and digital gain compensation is implemented for multiple cells, then both signal saturation and signal-to-quantization noise ratio are optimized, but device complexity increases
Solution Approach 1:
The patent designs the analog and digital gain compensators to process multiple cell signals simultaneously through a common structure. The control circuit universally manages the selection and coordination of both compensators, enabling them to handle multiple cells with varying signal strengths using a unified approach rather than requiring separate compensation circuits for each cell.
Solution Approach 2:
The patent merges the gain compensation functions into an integrated system where analog and digital gain compensators work together in a coordinated manner. The control circuit combines the control logic for both compensators, allowing them to operate as a unified signal processing chain that optimizes both saturation prevention and SQNR improvement while sharing common resources.
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 solution ensures improved SQNR performance and prevents signal saturation across multiple cells sharing a single LO, enhancing receiver performance without degradation.
Implementation Method 1
An LO is an electronic oscillator that may be used with a mixer to change the frequency of a signal. The process used to change the frequency may be referred to as heterodyning.
Data Source
AI summary
A digital signal processing circuit includes an analog gain compensator that compensates for an analog gain of a baseband signal including a plurality of component carriers (CCs) to output a compensated baseband signal; an analog-to-digital converter (ADC) that converts the compensated baseband signal into a first digital signal; a plurality of filtering circuits that generate a second digital signal from the first digital signal; and a control circuit. Each filtering circuit sequentially filters the first digital signal so that a corresponding one of the second digital signals retains one CC among the CCs, compensates for a digital gain, and a performs down-sampling. The control circuit generates an analog gain control signal for controlling the analog gain based on the second digital signals and a digital gain control signal for controlling the digital gain.