Inductively Coupled Multi-Stack Amplifier for Harmonic Suppression
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Solution Overview
Problem
RF circuitry, particularly power amplifiers, face challenges with harmonic distortions and reduced efficiency due to reactive components at intermediate nodes in transistor stacks, especially at millimeter-wave frequencies, affecting performance metrics like ACLR and EVM.
Innovation Solution
A multi-stack amplifier with inductive coupling between transistors in the stack to compensate for reactive components, using shunt inductors at intermediate nodes to resonate and trap harmonic distortions, and a reconfigurable transistor stack architecture with switches to dynamically adjust the number of active transistors based on operational state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If transistor stacks are used to amplify RF signals, then power output is increased, but reactive components at intermediate nodes cause harmonic distortions and reduce efficiency
Solution Approach 1:
Inductive elements are introduced as intermediary components at the intermediate nodes between transistors in the stack. These inductors compensate for the reactive components (capacitances) generated by the transistor gates and interconnects, creating a more balanced impedance environment that reduces harmonic distortions and improves power-added efficiency while maintaining high power output capability
2Power
If transistor stacks are used to amplify RF signals, then power output is increased, but harmonic distortions increase affecting ACLR and EVM
Solution Approach 1:
Inductive elements serve as mediator components that counterbalance the capacitive reactive effects at intermediate nodes. By providing inductive reactance that compensates for capacitive reactance, these elements reduce the formation of harmonic distortions, thereby improving spectral purity metrics like ACLR and EVM while preserving the high power output benefit of stacked transistor architecture
3Device complexity
If fixed transistor stack configuration is used, then device complexity is reduced, but adaptability to varying supply voltages and output powers is limited
Solution Approach 1:
The patent implements dynamic reconfigurability by introducing control circuits and switching mechanisms that allow the transistor stack configuration to be dynamically adjusted. This enables the amplifier to adapt its number of active transistors, supply voltage, and output power levels based on operational requirements, transforming a static fixed configuration into a dynamic adaptable system without excessive complexity increase
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
Improves amplifier performance by reducing ACLR and EVM and increasing power-added efficiency (PAE) through impedance matching and harmonic distortion suppression, enabling efficient operation across varying supply voltages and output powers.
Implementation Method 1
the first inductive element is arranged to be inductively coupled to the second inductive element
Implementation Method 2
using shunt inductors at intermediate nodes to resonate and trap harmonic distortions
Implementation Method 3
Improves amplifier performance by reducing ACLR and EVM and increasing power-added efficiency (PAE) through impedance matching and harmonic distortion suppression
Data Source
AI summary
Certain aspects of the present disclosure provide an inductively coupled multi-stack amplifier. An example amplifier includes a first transistor stack comprising a first input node, a first transistor, and a second transistor. The amplifier further includes a second transistor stack comprising a second input node, a third transistor, and a fourth transistor, wherein the first input node and the second input node form an input pair for a differential input signal. The amplifier further includes a first inductive element having a first terminal coupled between the first transistor and the second transistor. The amplifier further includes a second inductive element having a second terminal coupled to a drain of the second transistor, wherein the first inductive element is arranged to be inductively coupled to the second inductive element.