Low-Noise Amplifier Current-Source Switching for Large Input Tolerance
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Solution Overview
Problem
Conventional wireless systems face challenges with low noise amplifiers (LNAs) being adversely affected by power amplifiers, leading to increased chip count, complexity, and noise addition, as they are typically separated to manage different power levels effectively.
Innovation Solution
A low noise amplifier system with individual current sources for each input transistor, isolated when turned off and combined when turned on, using a coupling transistor to manage power levels and prevent noise addition, allowing the LNA to tolerate large input signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LNA and power amplifier are placed on separate chips to manage different power levels, then noise addition is minimized and reliability is improved, but chip count increases and device complexity increases
Solution Approach 1:
The patent combines the LNA and power amplifier onto a single chip, integrating both low-power receive functionality and high-power transmit functionality in one device. This merging eliminates the need for separate chips while managing the technical challenges through additional circuitry designed to isolate the two functions when needed.
Solution Approach 2:
The patent introduces isolation circuitry as an intermediary mechanism between the LNA and power amplifier. This intermediary includes switches and isolation circuits that prevent the high-power amplifier from adversely affecting the sensitive LNA, thereby enabling co-integration on a single chip without compromising LNA performance.
2Measurement precision
If LNA is designed to minimize noise addition, then signal-to-noise ratio is improved, but tolerance to large input signals deteriorates
Solution Approach 1:
The patent implements dynamic switching capability that allows the LNA to adapt its operating state. Switches can dynamically connect or disconnect the LNA from the antenna based on whether the device is in receive mode (needing low noise) or transmit mode (needing large signal tolerance), optimizing performance for each operational condition.
Solution Approach 2:
The patent applies preliminary protection by using switches to prevent large transmit signals from entering the LNA in the first place. The isolation circuitry is configured to block harmful large signals before they can adversely affect the LNA's noise performance or cause damage.
3Measurement precision
If LNA processes weak received signals, then sensitivity is improved, but susceptibility to interference from power amplifier increases
Solution Approach 1:
The patent uses isolation circuits and switches as intermediary elements positioned between the LNA and the rest of the system. These intermediaries selectively connect or disconnect the LNA from the antenna and other circuits, preventing power amplifier interference from reaching the sensitive LNA while allowing weak signal processing when needed.
Data Source
AI summary
Methods and systems for a low noise amplifier with tolerance to large inputs are disclosed. Aspects of one method may include providing an individual current source for each input transistor to a low noise amplifier (LNA), wherein the individual current sources may be isolated from each other when the LNA is turned off. The individual current sources may also form a common current source for the input transistors when the LNA is turned on. Accordingly, the input transistors to the LNA may float when the LNA is turned off, thereby coupling the input signal voltage to the source and drain terminals. The individual current sources may be isolated from each other by a coupling transistor that is turned off. When the LNA is turned on, the coupling transistor may be turned on to couple the individual current sources to each other to form the common current source for the input transistors.