Coupled-Inductor Multi-Stage Amplifier for Wideband Gain Scaling
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Solution Overview
Problem
Conventional multi-stage amplifiers face a trade-off between increasing overall gain and maintaining overall bandwidth, as adding stages reduces bandwidth due to band-limitation of individual stages.
Innovation Solution
The design incorporates intra-stage and inter-stage inductive coupling by laying out parts of the inductors adjacent and parallel to each other, enhancing coupling coefficients and effectively increasing the inductive load network's impedance, thereby boosting high-frequency gain and extending bandwidth without sacrificing it.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If additional stages are added to increase overall gain, then overall gain is improved, but overall bandwidth is reduced due to band-limitation of each stage
Solution Approach 1:
The patent merges the load inductor and inter-stage inductor into a coupled inductor structure, where the two inductors share a common magnetic core. This merging allows the inductors to provide both the load function and the inter-stage coupling function simultaneously, eliminating the need for separate components and reducing the overall bandwidth limitation imposed by individual stage bandwidth constraints.
Solution Approach 2:
The coupled inductor structure acts as an intermediary between stages, providing inductive coupling that extends the bandwidth. The magnetic coupling between the load inductor and inter-stage inductor creates a transmission line effect that maintains signal integrity across a wider frequency range, allowing additional stages to be added without the usual bandwidth penalty.
2Power
If conventional multi-stage amplifier topology is used, then high overall gain can be achieved, but bandwidth is limited by each individual stage
Solution Approach 1:
The patent combines the load network and inter-stage coupling network into a single coupled inductor structure. The first inductor serves as the load for the first common-source amplifier while simultaneously providing inductive coupling to the second stage. This merging eliminates the bandwidth limitations associated with separate load and coupling networks.
Solution Approach 2:
The patent changes the electrical parameters of the inductive network by using coupled inductors with optimized mutual inductance. This parameter change allows the network to provide both high impedance for gain and wide bandwidth for signal transmission, resolving the trade-off between gain and bandwidth in conventional multi-stage amplifiers.
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
This approach allows for additional stages to be added to achieve higher overall gain without reducing bandwidth, as the enhanced inductive coupling enlarges effective inductance and maintains high-frequency performance.
Implementation Method 1
a part of the first load inductor is laid out adjacent to and parallel with a part of the first inter-stage inductor, a part of the second load inductor is laid out adjacent to and parallel with a part of the second inter-stage inductor
Data Source
AI summary
A multi-stage amplifier includes a first stage comprising a first common-source amplifier, a first inductive load network comprising a serial connection of a first load resistor and a first load inductor, and a first source network configured to receive a first signal and output a first load signal, and a first inter-stage inductor configured to couple the first load signal to a second signal; and a second stage comprising a second common-source amplifier, a second inductive load network comprising a serial connection of a second load resistor and a second load inductor, and a second source network configured to receive the second signal and output a second load signal, and a second inter-stage inductor configured to couple the second load signal to a third signal, wherein the first load inductor and the second load inductor are laid out to enhance an inter-stage inductive coupling.