Tunable Balun Circuit with Integrated Bandpass Filter
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Solution Overview
Problem
Conventional baluns used in radio frequency systems are large, difficult to manufacture, and suffer from signal loss, leading to increased noise figure and reduced sensitivity in radio receivers, especially when transitioning between balanced and unbalanced signal structures.
Innovation Solution
A tunable electronic circuit that integrates the functions of a balun and a bandpass filter, utilizing a dielectric substrate with symmetrically connected coupling elements and distributed resonator elements to facilitate signal transition between balanced and unbalanced signal paths, providing impedance matching and filtering capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional baluns are used to transition between balanced and unbalanced signal structures, then signal conversion is achieved, but device size increases and manufacturing difficulty increases
Solution Approach 1:
The patent combines the balun function with a bandpass filter into a single integrated circuit. The coupling elements serve dual purposes: they perform the balanced-to-unbalanced signal conversion while simultaneously providing filtering functionality. This merger eliminates the need for separate balun and filter components, reducing overall device size and simplifying manufacturing while maintaining signal conversion capability.
Solution Approach 2:
The coupling elements in the patent are designed to perform multiple functions simultaneously: they act as impedance transformation elements for balanced-to-unbalanced conversion, serve as resonant elements for bandpass filtering, and provide signal coupling between different parts of the circuit. This multi-functionality reduces the total number of components needed and simplifies the overall device structure.
2Reliability
If conventional baluns are used for signal transition, then impedance matching is achieved, but signal loss increases and noise figure worsens
Solution Approach 1:
By integrating the bandpass filter functionality into the balun circuit, the patent reduces the number of discrete components and interconnections. This integration minimizes signal loss at connection points and reduces the overall noise figure, while the impedance matching capability is maintained through the carefully designed coupling elements.
3Object-affected harmful factors
If filtering components are added after the balun to reduce out-of-band signals, then filtering capability is improved, but device complexity and size increase
Solution Approach 1:
The patent merges the filtering function directly into the balun circuit by using the coupling elements as resonant structures. The bandpass filter response is achieved through the distributed resonator elements that are integrated within the same circuit footprint as the balun, eliminating the need for separate filtering components and reducing overall device complexity.
Solution Approach 2:
The coupling elements are designed to simultaneously provide impedance transformation for balanced-to-unbalanced conversion and bandpass filtering. This multi-functionality allows the circuit to reject out-of-band signals while maintaining compact size and simple structure, as the same elements perform both the signal conversion and filtering functions.
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 tunable circuit enables narrower bandwidths with improved filtering, reducing signal loss and noise figure, and allowing for efficient operation over a broader frequency range, enhancing the sensitivity of radio receivers.
Implementation Method 1
The resonator elements are cooperatively configured to produce a bandpass filter response in the tunable integrated microwave circuit when signals are communicated between the balanced signal structure and the unbalanced signal structure
Data Source
AI summary
Balun with tunable bandpass filter characteristic includes first, second and third coupling elements disposed on a substrate. The first and second coupling elements are arranged on the substrate relative to the third coupling element to couple two identical but out of phase signals to form a corresponding unbalanced signal in the third coupling element. A plurality of tunable resonator elements are distributed within an area of the substrate defined on one side by the first and second coupling elements and on an opposing side by the third coupling element. The tunable resonator elements are configured to selectively produce a bandpass filter response.