Broadband LNA Structure Using Offset Branches for 5G Bandwidth
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Solution Overview
Problem
Conventional single-ended low noise amplifiers (LNAs) with low-order inductor-capacitor (LC) matching networks fail to meet the wide bandwidth requirements of 5G front-end modules due to limited radio frequency (RF) signal bandwidth, and high-order LC networks increase insertion loss and implementation footprint.
Innovation Solution
A broadband LNA structure combining a main LNA with one or more offset LNAs, utilizing an input splitter to split RF signals into phase-shifted signals, which are then re-aligned and combined by an output combiner to achieve broader bandwidth while maintaining a low noise figure and compact implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If high order LC matching networks are used to widen bandwidth, then bandwidth is improved, but insertion loss and implementation footprint increase
Solution Approach 1:
The LNA is divided into multiple parallel branches (main LNA and offset LNAs), each handling different frequency ranges. This segmentation allows each branch to use simpler LC matching networks while collectively achieving wide bandwidth coverage, avoiding the need for complex high-order networks that would increase insertion loss.
Solution Approach 2:
The patent introduces a frequency-offset dimension by adding offset LNAs with different center frequencies. This dimensional extension allows the system to cover a wider bandwidth without increasing the complexity of individual LC matching networks, thereby maintaining low insertion loss while achieving wideband operation.
2Adaptability or versatility
If high order LC matching networks are used to widen bandwidth, then bandwidth is improved, but implementation footprint increases
Solution Approach 1:
By segmenting the LNA into parallel branches with simpler LC matching networks, the total component count and footprint are reduced compared to a single high-order network. Each branch uses lower-order matching elements, and their parallel arrangement achieves wide bandwidth with smaller individual components.
Solution Approach 2:
Multiple parallel LNA branches (main LNA and offset LNAs) are merged at the output to collectively provide wide bandwidth. This merging approach allows the system to achieve wideband performance through parallel simpler networks rather than a single complex high-order network, reducing overall implementation footprint.
3Device complexity
If conventional single-ended LNA structure is used, then implementation is simple, but bandwidth is limited
Solution Approach 1:
The single-ended LNA is segmented into multiple parallel branches (main LNA and offset LNAs), each with simple structures. This segmentation maintains relative structural simplicity while collectively achieving wide bandwidth, resolving the contradiction between simplicity and bandwidth performance.
Solution Approach 2:
The patent extends the single-ended LNA into multiple frequency-offset dimensions by adding parallel offset LNA branches. This dimensional expansion allows the system to maintain simple single-ended architecture in each branch while achieving wide bandwidth through their combined operation across different frequency dimensions.
Data Source
AI summary
A broadband low noise amplifier (LNA) structure (10) includes a main LNA (12), an offset LNA (14), an input splitter (16), and an output combiner (18). The input splitter (16) is configured to split a radio frequency (RF) input signal into a first RF input signal and a second RF input signal with difference phases, which are fed to the main LNA (12) and the offset LNA (14), respectively. Based on the first RF input signal, the main LNA (12) is configured to provide a first RF output signal, and based on the second RF input signal, the offset LNA (14) is configured to provide a second RF output signal. The output combiner (18) is configured to realign the first RF output signal and the second RF output signal, and configured to combine the first and second RF output signals to provide a combined RF output signal.