Mixer Circuit Leakage Compensation via Feedback Detection
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Solution Overview
Problem
Up-conversion mixers in radio transmitters exhibit leakage that degrades the spectral purity of transmitter output by introducing spurious signals, which existing technologies have not effectively mitigated.
Innovation Solution
A mixer circuit comprising a first oscillator, a second oscillator, an up-conversion mixer, a down-conversion mixer, and a detect and control unit, where a leakage correction signal is generated to counteract the spurious signals caused by mixer leakage, utilizing a multiplexer and digital-to-analog converters to add a complex constant to the input signal of the up-conversion mixer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If up-conversion mixer is used to produce radio transmit signals, then signal generation function is achieved, but spurious signals are generated due to leakage
Solution Approach 1:
The patent converts the harmful leakage signal into a useful correction mechanism by detecting the spurious signal and generating a correction signal that is added to the original input signal. The correction signal is designed to have opposite phase and equal amplitude to the leakage, thereby canceling it out. This transforms the harmful effect into a beneficial cancellation mechanism.
Solution Approach 2:
The patent implements a feedback mechanism where the output of the up-conversion mixer is fed back through a down-conversion mixer to detect the leakage signal. The detected spurious signal is then used to generate a correction signal that is fed back to the input stage. This closed-loop feedback system continuously monitors and corrects the leakage, improving spectral purity.
2Manufacturing precision
If leakage correction signal is generated and added to input signal, then spectral purity is improved, but device complexity increases
Solution Approach 1:
The patent makes the down-conversion mixer serve multiple functions: it acts as a normal down-converter for signal reception and simultaneously serves as a leakage detection device. By detecting the leakage signal during normal operation and using it to generate correction signals, the system achieves spectral purity improvement without adding dedicated detection hardware, thereby reducing overall device complexity.
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 effectively reduces or eliminates mixer leakage, ensuring the spectral purity of the transmitter output meets regulatory requirements by compensating the leakage signal with a sinusoidal correction signal of opposite phase and same amplitude.
Implementation Method 1
A first oscillator provides a first signal of a first frequency to a first input terminal of the up-conversion mixer. A second oscillator provides a second signal of a second frequency to a local oscillator input terminal of the down-conversion mixer.
Implementation Method 2
The up-conversion mixer has a first input terminal coupled to the first oscillator and an output terminal. The output signal is down-converted by mixing the output signal with the second signal
Implementation Method 3
The down-conversion mixer has a first input terminal coupled to the output terminal of the up-conversion mixer and a second input terminal coupled to the second oscillator
Implementation Method 4
A spurious signal is detected in the down-converted signal. A leakage correction signal is produced from or according to the spurious signal.
Implementation Method 5
compensating the leakage signal with a sinusoidal correction signal of opposite phase and same amplitude
Data Source
AI summary
A mixer circuit includes a first oscillator, a second oscillator, an up-conversion mixer, a down-conversion mixer, and a detect and control unit. The up-conversion mixer has a first input terminal coupled to the first oscillator and an output terminal. The down-conversion mixer has a first input terminal coupled to the output terminal of the up-conversion mixer and a second input terminal coupled to the second oscillator. The detect and control unit is coupled to the down-conversion mixer.