Mm-Wave Cascode Power Amplifier With Inductive Gain-Power Boost
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Solution Overview
Problem
Existing millimeter-wavelength power amplifiers face challenges in achieving high output power and gain due to low gain of individual amplifying cells and high loss in matching networks, leading to difficulties in reaching saturated output power and maintaining useful gain at higher frequencies.
Innovation Solution
The design incorporates a matched-cascode amp-cell with inductive components to increase impedance and conductance, and a differential slot power combiner/divider to enhance output power and gain, along with embedding techniques to boost power transfer and impedance matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional cascode amp-cells are used to increase supply voltage and output power, then output power increases, but inter-cell parasitic capacitance increases causing gain to drop at higher mm-wave frequencies
Solution Approach 1:
The amplifier is divided into multiple independent amp-cells connected in series, where each cell contributes to the overall output voltage swing. This segmentation allows the output power to be increased through voltage stacking while isolating the parasitic effects to individual cells, preventing cumulative parasitic capacitance degradation.
Solution Approach 2:
Each amp-cell is designed with optimized local characteristics including tailored transistor dimensions, biasing conditions, and matching network configurations. This local optimization ensures that each cell contributes maximally to output power while minimizing its individual parasitic effects, maintaining overall gain performance at mm-wave frequencies.
2Power
If series power combiners are used to increase output power, then output power increases, but input impedance becomes imbalanced due to parasitic capacitors causing gain to drop
Solution Approach 1:
The power combiner design intentionally employs asymmetric impedance transformation ratios for different input channels. By compensating for parasitic capacitor effects with unequal transformation ratios, the design achieves balanced input impedances despite the inherent asymmetry introduced by parasitic elements, maintaining optimal power transfer and gain.
3Power
If parallel power combiners are used to increase output power, then output power increases, but impedance transformation ratio increases causing matching network loss to increase and gain to drop
Solution Approach 1:
The design transitions from traditional planar parallel combiner architectures to a three-dimensional integrated structure where multiple combiner paths are stacked vertically. This dimensional change allows for reduced signal path lengths and optimized impedance transformations, decreasing matching network losses while maintaining high output power capability.
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 significantly increases output power and power gain at high millimeter-wave frequencies, overcoming the limitations of traditional designs by optimizing impedance and conductance, and improving power transfer efficiency.
Implementation Method 1
a first inductive component coupled between the drain terminal of the first transistor and the ground to increase the impedance between the drain terminal of the first transistor and the ground
Implementation Method 2
a second inductive component coupled between the drain terminal of the first transistor and the source terminal of the second transistor to increase the conductance in the output admittance at the output port
Data Source
AI summary
A power amplifier (amp) is disclosed. This power amp can include a first transistor configured in the common source (CS) amplification mode, wherein the gate terminal of the first transistor is used as the input port of the power amp; and a second transistor configured in the common gate (CG) amplification mode, wherein the drain terminal of the second transistor is used as the output port of the power amp. The power amp also includes a first inductive component coupled between the drain terminal of the first transistor and the ground to increase the impedance between the drain terminal of the first transistor and the ground, thereby increasing an output power at the output port. The power amp additionally includes a second inductive component coupled between the drain terminal of the first transistor and the source terminal of the second transistor to increase the conductance in the output admittance at the output port, thereby further increasing the output power at the output port.