RF Modulator Phase-Canceling Circuit for Third-Order Distortion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Signal transmitters face significant challenges in reducing third-order inter-modulation distortion, particularly due to nonlinear circuit elements and power amplification stages, which worsen under low power supply conditions, affecting the quality of RF signals in wireless transceivers.
Innovation Solution
A signal processing apparatus comprising up-converters and amplifiers that generate and combine baseband signals with a 180° phase difference, effectively canceling out third-order inter-modulation tones by aligning the phase difference between the signals to 180°/N, thereby reducing distortion and improving linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low power supply strategy is adopted to save power consumption, then power consumption is reduced, but third order inter-modulating distortion becomes worse
Solution Approach 1:
The baseband signal is segmented into two separate baseband signals that are processed through different signal paths. Each path contains an up-converter and power amplifier, allowing independent processing and combination of signals to cancel distortion components while maintaining low power operation.
Solution Approach 2:
The invention applies preliminary anti-action by introducing a second baseband signal with specific phase relationship (180°/N) that pre-compensates for the nonlinear distortion. The distortion components generated in both paths are designed to be out of phase, so they cancel each other when combined, preventing the harmful distortion from appearing in the final output.
2Device complexity
If nonlinear circuit elements are used in signal transmitter, then device complexity is reduced, but third order inter-modulation distortion is generated
Solution Approach 1:
The invention converts the harmful nonlinear distortion into a beneficial cancellation mechanism. By deliberately generating distortion components in two separate paths with controlled phase relationships, the distortion is transformed from an unwanted byproduct into a useful tool for self-cancellation, allowing nonlinear circuit elements to be used without degrading signal quality.
3Power
If power amplification stage is used to amplify RF signal, then signal power is increased, but third order inter-modulation distortion emerges
Solution Approach 1:
The power amplification function is segmented into two separate power amplifiers operating in parallel. Each amplifier processes a different baseband signal through its own up-conversion path, allowing the distortion products to be generated separately and then combined in a cancellation configuration, achieving high power output with reduced distortion.
Data Source
AI summary
A radio frequency (RF) modulator includes: converting means for up-converting a first and second baseband signals into a first and second up-converted signals with a reference clock, wherein a phase difference between the first and second baseband signals substantially equals 180°/N; and combining means for combining the first and second up-converted signals to generate an output signal.