Single-Ended LNA Active Balun for Low-Noise Differential Output
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Solution Overview
Problem
Current single-ended Low Noise Amplifiers (LNAs) in transceivers face challenges with increased second-order nonlinearity and complex calibration due to the use of single balance mixers, leading to noise suppression issues and bulky components, especially in multi-mode and multi-band transceivers.
Innovation Solution
A single-ended low noise amplifier with integrated active balun functionality is designed to generate a differential output, reducing second-order nonlinearity and noise figure, while minimizing additional current consumption and avoiding the use of bulky passive transformers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If single-ended LNAs with single-ended outputs are used to save input balls and chip area, then chip area is reduced, but second-order nonlinearity increases and complex calibration is required
Solution Approach 1:
The single-ended LNA output is segmented into two differential signals using a differential signal generation circuit. This segmentation allows the use of single-ended input (saving chip area) while producing differential output signals that can be processed by double balance mixers, thereby reducing second-order nonlinearity and simplifying calibration requirements.
Solution Approach 2:
A differential signal generation circuit is introduced as an intermediary between the single-ended LNA output and the mixer input. This intermediary circuit transforms the single-ended signal into differential signals, enabling the system to benefit from both single-ended input simplicity and differential signal performance without requiring complex calibration.
2Area of stationary object
If single balance mixers are used with single-ended LNAs, then chip area is reduced, but second-order nonlinearity increases
Solution Approach 1:
The single-ended output signal is segmented into two differential signals with opposite polarity. This segmentation enables the use of double balance mixers which inherently suppress second-order nonlinearity, while maintaining the area efficiency of single-ended input design.
Solution Approach 2:
Instead of using a single balance mixer with single-ended signals, the invention inverts the approach by generating differential signals from the single-ended output and using a double balance mixer. This inversion of the signal type (from single-ended to differential) eliminates second-order nonlinearity while preserving area efficiency.
3Object-generated harmful factors
If fully differential LNAs are used to reduce second-order nonlinearity, then nonlinearity is reduced, but input ball requirements increase
Solution Approach 1:
The invention applies segmentation by keeping the LNA input single-ended (requiring only one input ball) while segmenting the output signal into differential components. This approach achieves the nonlinearity reduction of fully differential LNAs without increasing the number of input balls, as the differential transformation occurs after amplification.
Solution Approach 2:
A differential signal generation circuit serves as an intermediary that transforms the single-ended LNA output into differential signals. This intermediary enables the system to use a single input ball while achieving the performance benefits of fully differential operation, including reduced second-order nonlinearity.
Data Source
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AI summary
Embodiments provide an amplification circuit, an apparatus for amplifying, a low noise amplifier, a radio receiver, a mobile terminal, a base station, and a method for amplifying. An amplification circuit (10) for amplifying a radio signal comprises a first amplification stage (12) configured to amplify an input signal, Vin(t), to obtain an intermediate signal. The amplification circuit (10) further comprises a cascoding circuit (14) configured to amplify the intermediate signal to obtain a first output signal Voutn(t). The amplification circuit (10) further comprises a second amplification stage (16) configured to amplify the intermediate signal to obtain a second output signal, Voutp(t).