RF Amplifier Bootstrap Circuitry for Higher Linearity
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Solution Overview
Problem
RF amplifier circuitry faces challenges in achieving improved linearity to meet stringent intermodulation distortion requirements without increasing size, cost, or power consumption, often requiring a tradeoff between second-order and third-order non-linearity.
Innovation Solution
Incorporating bootstrap circuitry that provides a low impedance path for signals at twice the operating frequency and a high impedance path for other frequencies, allowing for improved third-order intercept point (IIP3) without balancing biasing for second-order non-linearity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional RF amplifier circuitry is used to meet stringent intermodulation distortion requirements, then linearity must be improved, but size, cost, and power consumption increase
Solution Approach 1:
The patent introduces bootstrap circuitry as an intermediary component between the amplifier stages. This bootstrap circuitry provides a low impedance path for second harmonic signals (twice the operating frequency) while maintaining high impedance for other frequencies, thereby reducing secondary third-order intermodulation products without requiring complete redesign of the amplifier architecture. This intermediary solution improves linearity (IIP3) without proportionally increasing overall device complexity, size, cost, or power consumption.
2Manufacturing precision
If biasing is adjusted to minimize inherent third-order intermodulation, then third-order linearity improves, but second-order non-linearity increases
Solution Approach 1:
The patent converts the harmful second-order non-linearity into a beneficial effect by using the bootstrap circuitry to provide a low impedance path specifically for second harmonic signals. By intentionally allowing second-order distortion products to be generated and then providing a dedicated path for these second harmonic signals, the system reduces secondary third-order intermodulation products. This approach allows the amplifier to be biased for minimized inherent third-order intermodulation without needing to balance against second-order non-linearity, as the bootstrap circuitry handles the second-order products constructively.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces secondary third-order intermodulation products, enabling the RF amplifier to be biased for minimized inherent third-order intermodulation without affecting second-order intermodulation, thus enhancing IIP3 while maintaining performance without increased size, cost, or power consumption.
Implementation Method 1
The bootstrap circuitry is configured to provide a low impedance path between the control node and the second amplifier node for signals having a second frequency that is equal to about twice the first frequency
Data Source
AI summary
Radio frequency (RF) amplifier circuitry includes an input node, an output node, an amplifier, and bootstrap circuitry. The amplifier includes a control node coupled to the input node, a first amplifier node coupled to the output node, and a second amplifier node coupled to a fixed potential. The amplifier is configured to receive an input signal having a first frequency at the control node and change an impedance between the first amplifier node and the second amplifier node based on the input signal. The bootstrap circuitry is coupled between the control node and the second amplifier node. The bootstrap circuitry is configured to provide a low impedance path between the control node and the second amplifier node for signals having a second frequency that is equal to about twice the first frequency and provide a high impedance path for signals having a frequency outside the second frequency.