Wireless Transmission Circuit for On-Chip Second Harmonic Cancellation
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Solution Overview
Problem
Wireless transmitters, particularly at 2.4 GHz, generate second and third harmonics that interfere with other frequency bands, leading to poor transmission performance and quality, and existing filters require additional space and have poor quality factors.
Innovation Solution
A wireless transmission circuit comprising induction circuits, detection circuits, and signal adjustment circuits that detect and adjust common mode signals to reduce second harmonic interference, integrating components within a chip to minimize external filter requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filter composed of an inductor and a capacitor is disposed on a chip, then second harmonic interference can be reduced, but an extra area is required and the quality factor Q of the inductor is poor
Solution Approach 1:
The patent extracts the second harmonic signal from the main signal path using a coupling capacitor, separates it for processing, and then removes it through inversion. This allows harmonic reduction without requiring large inductor-capacitor filters on the chip, thus reducing the occupied area while maintaining filtering effectiveness.
Solution Approach 2:
The patent converts the harmful second harmonic signal into a beneficial element by detecting it, inverting its phase, and using it to cancel itself out. This self-cancellation approach eliminates the need for traditional bulky filters while achieving the same harmonic reduction goal.
2Object-affected harmful factors
If a filter composed of an inductor and a capacitor is disposed on a chip, then second harmonic interference can be reduced, but the quality factor Q of the inductor is poor
Solution Approach 1:
Instead of relying on the poor quality factor of on-chip inductors, the patent converts the harmful harmonic signal into a self-canceling signal through phase inversion. This approach bypasses the limitation of low-Q inductors entirely by using active signal processing rather than passive filtering.
Solution Approach 2:
The patent replaces the mechanical/physical inductor-capacitor filter system with an electronic signal processing system that uses detection, phase inversion, and cancellation. This substitution achieves better filtering performance without being constrained by the physical limitations of on-chip inductors.
3Object-affected harmful factors
If traditional filtering methods are used, then second harmonic interference can be reduced, but the circuit area increases
Solution Approach 1:
The patent extracts only the second harmonic component from the full signal using a coupling capacitor, processes it separately, and cancels it out. This selective extraction approach is more area-efficient than using a comprehensive filter that would need to handle all frequency components.
Solution Approach 2:
The patent creates a copy of the second harmonic signal through the coupling capacitor, processes this copy by inverting its phase, and then combines it with the original signal to achieve cancellation. This copying approach allows for targeted harmonic reduction without filtering the entire signal path.
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 second harmonic interference, improving transmission quality and reducing the circuit area needed for filtering, thereby enhancing performance and efficiency.
Implementation Method 1
a first induction circuit (110), a second induction circuit (120), a third induction circuit (130)
Implementation Method 2
a detection circuit (140) is configured to detect a common mode signal associated with the first signal
Data Source
AI summary
A wireless transmission circuit includes a first induction circuit, a second induction circuit, a detection circuit, a first signal adjustment circuit, and a third induction circuit. The first induction circuit is configured to receive a first signal outputted from a power amplifier. The second induction circuit is configured to output the received first signal as a second signal. The detection circuit is configured to detect a common mode signal associated with the first signal. The first signal adjustment circuit is configured to adjust a phase or an amplitude of the common mode signal to generate a third signal. The third induction circuit is configured to receive the third signal and be coupled to the second induction circuit to reduce a second harmonic in the second signal.