Feedback-Linearized Filtering Mixer for Stable I/Q Modulation
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Solution Overview
Problem
There is a trade-off between linearity and signal-to-noise ratio (SNR) performance in I/Q modulators within transmitters, which are affected by process, voltage, and temperature (PVT) variations, requiring robust solutions to ensure performance consistency in mass production.
Innovation Solution
A mixer with a filtering function and a method for linearization that includes an amplifier, a transconductance device, and a feedback network, where the transconductance device is part of a closed-loop filter, improving linearity by reducing the impact of active device transconductance and maintaining cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If input voltage levels are limited to ensure linearity, then linearity performance is improved, but signal-to-noise ratio performance deteriorates
Solution Approach 1:
The patent implements a feedback network that feeds back a portion of the output signal to the input, creating a closed-loop system. This feedback mechanism linearizes the mixer's transfer function, allowing the system to maintain linearity performance while operating at higher input voltage levels, thereby improving signal-to-noise ratio without sacrificing linearity.
Solution Approach 2:
The patent changes the operating parameters of the mixer by introducing a feedback path that dynamically adjusts the effective transfer function. By modifying the system's parameter relationships through feedback, the mixer can operate at higher input levels while maintaining linear performance, resolving the trade-off between linearity and signal-to-noise ratio.
2Reliability
If large scale simulations are performed to ensure performance under PVT variation, then performance robustness is improved, but design complexity and time increase
Solution Approach 1:
The feedback network compensates for PVT variations by dynamically adjusting the transfer function in response to changing conditions. This closed-loop approach inherently provides robustness against process, voltage, and temperature variations without requiring extensive simulations for each scenario, reducing design complexity while maintaining performance reliability.
Solution Approach 2:
The feedback mechanism pre-compensates for potential PVT variations by continuously monitoring and adjusting the output. This proactive approach cushions against performance degradation from PVT effects without requiring post-manufacturing adjustments or extensive simulation-based optimization for each PVT corner case.
Data Source
AI summary
A mixer with a filtering function and a method for linearization of the mixer are provided. The mixer includes at least one amplifier, a transconductance device and a feedback network. The at least one amplifier is configured to output a filtered voltage signal according to an input voltage signal. The transconductance device is coupled to the at least one amplifier, and is configured to generate a filtered current signal according to the filtered voltage signal. The feedback network is coupled between any output terminal among at least one output terminal of the transconductance device and an input terminal of the at least one amplifier. More particularly, the mixer is configured to output a modulated signal according to the filtered current signal.