Two-Stage Complementary Amplifier for Triode-Region Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing amplifiers using a combination of NMOST and PMOST in a hybrid differential common-source topology suffer from linearity degradation when the transistors enter the triode region due to source degeneration and impedance issues.
Innovation Solution
A two-stage complementary amplifier (TSCA) with a common-source input stage and common-gate output stage, featuring stacked NMOST and PMOST configurations in cascode and common-source topologies, and tightly coupled inductors to maintain linearity even when transistors enter the triode region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a hybrid differential common-source topology with NMOST and PMOST is used, then source degeneration effects are mitigated, but linearity degrades when transistors enter the triode region due to large input voltage
Solution Approach 1:
The amplifier is divided into two distinct stages: a common-source input stage and a common-gate output stage. This segmentation allows each stage to perform its specific function optimally - the input stage provides voltage-to-current conversion while the output stage maintains linearity through current buffering, resolving the linearity degradation issue when transistors enter the triode region
Solution Approach 2:
Instead of using a common-source output stage that is prone to linearity degradation, the invention inverts the approach by using a common-gate output stage. The common-gate configuration inherently provides better linearity by presenting a low impedance to the input stage and buffering the current, thus maintaining linearity even when transistors operate in the triode region
2Use of energy by moving object
If inductors are tightly coupled in parallel, then magnetic energy storage is enhanced through strong mutual coupling, but device complexity increases
Solution Approach 1:
Three inductors (L1, L2, and L3) are merged into a tightly coupled parallel configuration where they share mutual inductance. This merging allows the inductors to function as a unified magnetic energy storage element, enhancing the overall inductance and energy storage capability while managing the layout complexity through integrated design
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
The TSCA maintains high linearity by ensuring the output stage presents a consistent load regardless of input signal amplitude, improving linearity despite transistors entering the triode region, and enhancing magnetic energy storage through strong mutual coupling of inductors.
Implementation Method 1
the third inductor, the fourth inductor, and the fifth inductor are laid out tightly and substantially in parallel to have strong mutual coupling
Data Source
AI summary
A two-stage complementary amplifier (TSCA) includes a common-source input stage comprising a stack-up of a n-type common-source amplifier and a p-type common-source amplifier configured to receive a first signal and a second signal and output a third signal and a fourth signal across a first inductor and a second inductor, respectively; a common-gate output stage having a stack-up of a n-type common-gate amplifier and a p-type common-gate amplifier configured to receive the third signal and the fourth signal via a first capacitor and a second capacitor, respectively, and output a fifth signal and a sixth signal across a third inductor and a fourth inductor, respectively; and a fifth inductor terminated with a load, wherein the third inductor, the fourth inductor, and the fifth inductor are laid out tightly and substantially parallel to have strong mutual coupling.