Split Cascode Amplifier Drain Coupling for Noise Figure and Isolation
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Solution Overview
Problem
Existing amplifier configurations face challenges in achieving sufficient isolation and noise figure improvement when operating in split mode, particularly when handling non-contiguous intra-band carrier aggregate signals.
Innovation Solution
The proposed amplifier circuit configuration includes a cascode architecture with switchable coupling between the drains of the input FETs, allowing for controlled noise reduction and improved output-to-output isolation in split mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a passive splitter is used to split the amplifier output to multiple downconverters, then the amplifier can serve multiple channels, but the isolation between output ports deteriorates
Solution Approach 1:
The invention divides the amplifier into multiple independent amplifier units, each with its own output port. This segmentation eliminates the need for a passive splitter, as each amplifier unit directly connects to a specific downconverter. The isolation between output ports is improved because each amplifier unit operates independently without sharing a common splitter component.
2Reliability
If the gates of input FETs are coupled together to improve linearity, then the amplifier performance improves, but the noise figure deteriorates in split mode
Solution Approach 1:
The invention dynamically switches the coupling configuration of input FET gates based on the operating mode. In single-channel mode, the gates are coupled together to improve linearity. In split-mode operation, the gates are decoupled to improve noise figure. This dynamic reconfiguration allows the amplifier to optimize performance for each specific operating condition.
3Adaptability or versatility
If the amplifier operates in split mode to handle non-contiguous intra-band carrier aggregate signals, then the adaptability improves, but the noise figure and isolation deteriorate
Solution Approach 1:
The amplifier is segmented into multiple independent amplifier units, each capable of handling specific frequency channels. This segmentation allows the amplifier to process non-contiguous intra-band carrier aggregate signals effectively while maintaining good isolation between output ports, as each amplifier unit has its dedicated output path without sharing a passive splitter.
Solution Approach 2:
The amplifier dynamically reconfigures its internal coupling structures based on the operating mode. In split-mode operation for NCIB CA signals, the invention switches off the gate coupling to improve noise figure while maintaining the ability to handle multiple non-contiguous channels. This dynamic adaptation resolves the contradiction between versatility and noise performance.
Data Source
AI summary
An amplifier circuit configuration capable of processing non-contiguous intra-band carrier aggregate (CA) signals using amplifiers is disclosed herein. In some cases, each of a plurality of amplifiers is an amplifier configured as a cascode (i.e., a two-stage amplifier having two transistors, the first configured as a “common source” input transistor, e.g., input field effect transistor (FET), and the second configured in a “common gate” configuration as a cascode output transistor, (e.g. cascode output FET). In other embodiments, the amplifier may have additional transistors (i.e., more than two stages and/or stacked transistors). The amplifier circuit configuration can be operated in either single mode or split mode. A switchable coupling is placed between the drain of the input FETs of each amplifier within the amplifier circuit configuration. During split mode, the coupling is added to the circuit to allow some of the signal present at the drain of each input FET to be coupled to the drain of the other input FET.