Transformer-Based Wideband Filter Ripple Reduction
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Solution Overview
Problem
Radio frequency filtering circuitry in electronic devices experiences uneven gain at different frequency poles, leading to in-band ripple, which results in poor error vector magnitude (EVM) and signal-to-noise ratio (SNR) values during signal transmission.
Innovation Solution
A transformer-based resonator with a conductive loop and programmable or static resistor is used to induce currents in a series of inductors, adjusting the coupling factor to reduce in-band ripple by correlating the gain peaks of the frequency response, thereby smoothing out the frequency response across a wide range of frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a transformer-based resonator is used to provide wideband filtering, then the bandwidth is increased, but in-band ripple appears in the frequency response
Solution Approach 1:
A conductive loop is introduced as an intermediary element that couples to the transformer-based resonator. This loop provides an additional degree of freedom to adjust the frequency response independently from the main resonator structure, allowing bandwidth expansion while compensating for in-band ripple through proper loop design and positioning
Solution Approach 2:
The patent adjusts multiple parameters including the conductive loop geometry, its coupling to the resonator, and the resistor value to optimize the frequency response. By changing these parameters, the system achieves both wide bandwidth and reduced in-band ripple, resolving the contradiction between bandwidth and frequency response uniformity
2Manufacturing precision
If the conductive loop couples to both inductors, then in-band ripple is reduced, but odd mode currents are affected
Solution Approach 1:
The conductive loop is strategically positioned and dimensioned to create different coupling strengths with the first and second inductors. This asymmetric local coupling allows the loop to primarily interact with even mode currents while minimizing interference with odd mode currents, thus reducing in-band ripple without significant impact on odd mode operation
Solution Approach 2:
The patent employs asymmetric coupling of the conductive loop to the transformer inductors, where the loop couples more strongly to one inductor than the other. This asymmetry creates selective interaction with specific current modes, allowing suppression of even mode ripple while preserving odd mode current characteristics
3Manufacturing precision
If a resistor is added to the conductive loop to reduce gain peaks, then in-band ripple decreases, but device complexity increases
Solution Approach 1:
The conductive loop with resistor serves multiple functions simultaneously: it provides additional filtering action, adjusts the frequency response to reduce in-band ripple, and can be integrated into existing circuit layouts without requiring separate dedicated components. This multi-functionality reduces the net increase in device complexity while achieving the desired frequency response uniformity
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 in-band ripple, improving the EVM and SNR values by ensuring similar gain across the frequency range, enhancing the performance of radio frequency filtering circuitry in electronic devices.
Implementation Method 1
When a power source supplies current to the first inductor, the first inductor induces a current in the second inductor via a 'transformer effect'
Implementation Method 2
The conductive loop inductively couples to at least one of the first inductor and the second inductor, inducing a third current in the conductive loop
Data Source
AI summary
A radio frequency filtering circuitry includes a first inductor, a second inductor, and a conductive loop. The first inductor receives a first current that induces a second current in the second inductor upon receiving the first current. The first inductor and/or the second inductor induce a third current in the conductive loop. The conductive loop adjusts the third current to reduce a first gain peak of an output signal to correlate to a second gain peak of the output signal.