I/Q Mixer Detector Circuit Using Squaring and DC Filtering
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Solution Overview
Problem
Radio frequency (RF) transceivers face challenges in detecting local oscillator leakage and image tone, which cause I/Q imbalance, leading to performance issues and calibration difficulties in RF transceivers.
Innovation Solution
A detector circuit comprising a squaring circuit and a DC current absorber is used to generate an output current from the power amplifier, filtering out the DC component to isolate the local oscillator leakage and image tone, which is then supplied to a transimpedance amplifier for detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional detection methods are used to detect local oscillator leakage and image tone, then the detection process requires additional hardware components and large capacitors/inductors, but this increases device complexity, power consumption, and calibration difficulty
Solution Approach 1:
The patent combines the detection of local oscillator leakage and image tone into a single detector circuit that processes both signals simultaneously. The squaring circuit and DC current absorber are integrated to detect both types of interference without requiring separate detection paths, thereby reducing overall device complexity while maintaining detection accuracy.
Solution Approach 2:
The detector circuit is designed to perform multiple detection functions using a unified architecture. It can detect both local oscillator leakage and image tone through the same signal path and processing stages, eliminating the need for dedicated hardware for each detection task and reducing the overall hardware footprint.
2Measurement precision
If traditional detection methods are used to detect local oscillator leakage and image tone, then the detection process requires additional hardware components and large capacitors/inductors, but this increases power consumption
Solution Approach 1:
The patent combines the detection of local oscillator leakage and image tone into a single detector circuit that processes both signals simultaneously. The squaring circuit and DC current absorber are integrated to detect both types of interference without requiring separate detection paths, thereby reducing overall device complexity while maintaining detection accuracy.
Solution Approach 2:
The detector circuit utilizes the existing power amplifier output signal to perform self-detection of local oscillator leakage and image tone. By processing the PA output through the squaring circuit and DC current absorber, the system achieves detection functionality without requiring additional external calibration signals or test equipment, thereby reducing power consumption.
3Productivity
If traditional detection methods are used to detect local oscillator leakage and image tone, then the calibration process becomes more difficult and less efficient, but using simplified detection may reduce measurement precision
Solution Approach 1:
The detector circuit provides feedback signals that enable automatic calibration of the RF transceiver. By continuously monitoring local oscillator leakage and image tone levels, the system can adjust mixer parameters and I/Q balance automatically, improving calibration efficiency while maintaining high measurement precision through the feedback control mechanism.
Solution Approach 2:
The patent replaces traditional manual or complex mechanical calibration procedures with an electronic detection and adjustment system. The detector circuit electronically measures local oscillator leakage and image tone, and the system automatically adjusts calibration parameters through electronic control, eliminating the need for manual intervention and improving both efficiency and precision.
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 solution effectively detects and calibrates local oscillator leakage and image tone, reducing I/Q imbalance and improving RF transceiver performance without requiring additional hardware or large capacitors/inductors, thus enhancing calibration efficiency and reducing power consumption.
Implementation Method 1
a squaring circuit configured to receive an output of a power amplifier of a radio transmitter and configured to produce an output current, the output of the power amplifier including: a desired tone; a local oscillator leakage tone; and an image tone, and the output current of the squaring circuit including: a direct current (DC) component including a function of the desired tone; an alternating current (AC) component including: a function of the local oscillator leakage tone; and a function of the image tone
Implementation Method 2
a DC current absorber electrically connected to an output terminal of the squaring circuit, the DC current absorber being configured to filter out the DC component of the output current of the squaring circuit to produce a filtered output of the squaring circuit, the filtered output including the function of the local oscillator leakage tone and the function of the image tone
Implementation Method 3
The filtered output may be supplied to a transimpedance amplifier
Data Source
AI summary
A detector circuit includes: a squaring circuit configured to receive an output of a power amplifier of a radio transmitter and to produce an output current, the output of the power amplifier including: a desired tone; a local oscillator leakage tone; and an image tone, and the output current of the squaring circuit including: a direct current (DC) component including a function of the desired tone and an alternating current (AC) component; and a DC current absorber electrically connected to an output terminal of the squaring circuit, the DC current absorber being configured to filter out the DC component of the output current of the squaring circuit to produce a filtered output of the squaring circuit, the filtered output including the AC component including functions of the local oscillator leakage tone and the image tone.