Receiver Mode Switching for Image Rejection and Noise Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Receivers with very low intermediate frequency (VLIF) architecture face challenges in maintaining low amplitude and phase imbalance, which affects image rejection and requires costly calibration circuits to meet stringent adjacent channel rejection specifications.
Innovation Solution
A receiver that automatically switches between VLIF and zero intermediate frequency (ZIF) modes based on monitored metrics such as received signal strength indication (RSSI) and adjacent channel detection, using a controller to configure the front-end and back-end components to optimize performance and bypass digital mixers as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If VLIF architecture is used to minimize DC offset and 1/f noise, then receiver sensitivity is improved, but mixer imbalance issues limit image rejection and adjacent channel rejection performance
Solution Approach 1:
The receiver dynamically switches between VLIF and ZIF modes based on operating conditions. The mode selection is controlled by a controller that monitors signal characteristics and adjusts the architecture accordingly, allowing the system to optimize both sensitivity and image rejection performance for different scenarios
Solution Approach 2:
The system changes the intermediate frequency parameter dynamically. In VLIF mode, a very low intermediate frequency is used to minimize DC offset and 1/f noise. In ZIF mode, the intermediate frequency is set to zero to maximize image rejection. The controller selects the appropriate frequency parameter based on current operating conditions
2Manufacturing precision
If calibration circuits are added to compensate for poor adjacent channel rejection, then image rejection performance is improved, but device complexity and cost increase
Solution Approach 1:
Instead of using fixed calibration circuits, the system dynamically selects between VLIF and ZIF modes to achieve good adjacent channel rejection without requiring complex calibration hardware. The mode switching itself provides the necessary performance adjustment
Solution Approach 2:
The patent extracts the calibration function by using mode switching between VLIF and ZIF architectures. Rather than adding separate calibration circuits to correct mixer imbalance, the system achieves the desired performance by selecting the appropriate operating mode, thereby removing the need for complex calibration hardware
3Manufacturing precision
If ZIF mode is used to achieve excellent image rejection, then adjacent channel rejection is improved, but DC offset and 1/f noise problems increase
Solution Approach 1:
The receiver dynamically switches between ZIF and VLIF modes based on the specific operating conditions. When excellent image rejection is the priority, ZIF mode is selected. When minimizing DC offset and 1/f noise is more important, VLIF mode is selected. This dynamic adaptation allows the system to avoid the harmful effects of each mode by using the appropriate mode for each situation
Solution Approach 2:
The system changes the intermediate frequency parameter to resolve the contradiction. In ZIF mode, the intermediate frequency is zero, providing excellent image rejection but introducing DC offset and 1/f noise. In VLIF mode, a very low intermediate frequency is used, minimizing DC offset and 1/f noise while maintaining good image rejection. The controller selects the appropriate frequency parameter based on current needs
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 improves receiver performance by dynamically adjusting the operating mode to enhance image rejection and reduce complexity and power consumption, effectively meeting the stringent image rejection requirements without the need for costly calibration.
Implementation Method 1
a mixer to convert the received signal to an intermediate frequency signal, comprising a first mixer to convert the received signal to in-phase (I) and quadrature-phase (Q) components of an intermediate frequency signal
Implementation Method 2
a local oscillator to generate a local oscillator signal at a frequency that is different from a frequency of the received signal
Implementation Method 3
a first analog-to-digital converter to convert the in-phase component to a digital signal and a second analog-to-digital converter to convert the quadrature-phase component to a digital signal
Data Source
AI summary
Methods and corresponding systems for receiving a radio frequency signal include a receiver capable of switching operating modes and operable to receive the radio frequency signal in any of the operating modes. A metric monitor is coupled to the receiver and operable to provide a metric. A controller is responsive to the metric and operable to switch the receiver between the operating modes. The operating modes can include a zero intermediate frequency (ZIF) mode and a very low intermediate frequency (VLIF) mode. The metric can include a received signal strength indicator (RSSI) and an adjacent channel indicator. The receiver can be configured to operate in the ZIF mode in response to the RSSI value satisfying a threshold and configured to operate in the VLIF mode in response to the RSSI value failing to satisfy the threshold.