3D Common-Gate Amplifier Layout for Millimeter-Wave AC Grounding
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Solution Overview
Problem
Conventional common-gate amplifier circuits face challenges in achieving optimal AC grounding at high frequencies due to layout parasitics, which result in reduced maximum frequency and performance, especially at millimeter-wave frequencies, due to parasitic inductance and resistance.
Innovation Solution
The implementation of a 3D transistor structure with vertically stacked metal layers forming capacitors between the gate, well, and substrate, eliminating the need for external capacitors and reducing parasitic inductance by integrating capacitance at the junctions between these components, thereby achieving AC grounding and minimizing interconnection length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitor is placed in near proximity to a gate of the amplifier circuit to ensure AC ground, then AC grounding is improved, but parasitic inductance and resistance increase, reducing the maximum frequency of operation
Solution Approach 1:
The patent merges the AC grounding function with the existing gate structure by utilizing the gate's inherent capacitance to ground through the well-substrate junction, eliminating the need for separate external capacitors and their associated parasitic interconnections
Solution Approach 2:
The patent extracts the external capacitor component from the circuit design and replaces it with the intrinsic capacitance formed by the gate-well-substrate structure, thereby removing the source of parasitic inductance and resistance
2Reliability
If external capacitors are used for AC grounding, then grounding function is achieved, but device area increases
Solution Approach 1:
The patent combines multiple functions (AC grounding, gate structure, and well-substrate junction) into a single integrated structure, eliminating the need for separate capacitor components and reducing overall circuit area
Solution Approach 2:
The gate structure serves multiple functions simultaneously: it provides the transistor gate function, forms a capacitor through overlap with metal layers, and creates a junction capacitance with the well-substrate for AC grounding, thereby eliminating dedicated capacitor space
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 enhances stability, increases maximum frequency, and improves large signal performance by reducing parasitic inductance and area requirements, achieving area savings and improved performance compared to traditional designs.
Implementation Method 1
At least one capacitance is in at least one of a junction between the at least one well and the substrate
Implementation Method 2
a second metal layer overlapped over the first metal layer to form a first capacitor; a third metal layer connected with vias to the first metal layer and overlapped with the second metal layer to form a second capacitor
Data Source
AI summary
The present disclosure relates to semiconductor structures and, more particularly, to a common-gate amplifier circuit and methods of operation. The structure includes at least one well in a substrate, a first metal layer connected to a gate of a transistor circuit, a second metal layer overlapped over the first metal layer to form a capacitor, and a third metal layer connected with vias to the first metal layer and overlapped with the second metal layer to form a second capacitor. At least one capacitance in at least one of a junction between the at least one well and the substrate and between overlapped metal layers of the first metal layer, the second metal layer, and the third metal layer.