Folded-Cascode LNA Topology Without Inductors for Linearity
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Solution Overview
Problem
Conventional low-noise amplifiers (LNAs) face limitations in linearity due to high current and power requirements, and the use of inductors increases chip size, making it challenging to achieve high input sensitivity and compact integration.
Innovation Solution
The implementation of a folded-cascode amplifier with gain boosting, which includes capacitors and resistors to reduce input referred noise and output impedance, allowing for improved noise figure and linearity without the need for inductors, enabling smaller chip area integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high current is used to achieve high linearity, then linearity is improved, but power consumption increases
Solution Approach 1:
The patent changes the circuit topology from conventional to folded-cascode configuration, which fundamentally alters the relationship between current and linearity. This structural parameter change enables high linearity to be achieved without proportionally increasing power consumption, as the folded-cascode architecture provides inherent linearity improvement through its specific transistor arrangement and signal path.
2Reliability
If inductors are used to achieve low noise, then noise figure is improved, but chip area increases
Solution Approach 1:
The patent extracts and eliminates the inductor component from the circuit design. By removing the inductor and replacing it with an active folded-cascode amplifier circuit, the design achieves low noise performance without the large chip area that inductors occupy. This extraction of the problematic passive component is the core solution to the area-noise figure contradiction.
Solution Approach 2:
The patent substitutes passive inductive elements with active electronic circuitry. Instead of using physical inductors that occupy significant chip area, the design employs transistors and capacitors in a folded-cascode configuration to achieve the same noise reduction function, replacing mechanical/passive components with active electronic ones.
3Reliability
If high current is used to achieve high linearity, then linearity is improved, but device complexity increases
Solution Approach 1:
The patent changes the fundamental circuit parameter from current-based linearity improvement to topology-based linearity improvement. The folded-cascode configuration inherently provides better linearity through its structure, eliminating the need for high current operation and the associated complexity of current control and thermal management circuits.
Data Source
AI summary
An amplifier with gain boosting is disclosed according to an aspect of the subject technology. The gain boosting may be used to improve the noise figure of the amplifier, and may be achieved by feeding an input signal to the gates of multiple transistors in the amplifier, where each transistor provides a current gain contributing to the total current gain of the amplifier. The amplifier may also include an output driver stage for increasing the driving capability of the amplifier. The amplifier may also include a feedback resistor and an input resistor to obtain a gain with high linearity.