Integrated RF Amplifier Cell Layout for Phase Matching
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Solution Overview
Problem
Current integrated RF-amplifiers face limitations in achieving higher output power due to the limited area available for active dies within the package, which restricts the number of amplifier cells and results in insufficient phase and amplitude matching across cells, leading to reduced power capability.
Innovation Solution
The integrated RF-amplifier structure features a unique arrangement of amplifier cells with input and output pads displaced perpendicular to each other, interconnected by bond wires that provide equal phase shifts and amplitude, allowing for a larger active die area and increased output power by doubling the number of cells within the same package.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If amplifier cells are arranged in a row within the package, then the phase delay from input to output can be kept identical for all cells, but the number of cells is limited by the package width and the active dies only cover a small portion of the available area
Solution Approach 1:
The patent transitions from a one-dimensional row arrangement to a two-dimensional layout where amplifier cells are positioned at different locations within the package. The input pads are arranged along a first direction and output pads along a second direction, allowing cells to be distributed across the package area rather than confined to a single row, thereby increasing the usable active die area while maintaining phase matching through careful geometric arrangement.
2Power
If the number of amplifier cells is increased to achieve higher output power, then the power capability improves, but the phase and amplitude matching across cells becomes difficult to maintain
Solution Approach 1:
The patent employs asymmetric positioning of input and output pads relative to the amplifier cells. The input pads are arranged along a first direction while output pads are arranged along a second direction, creating an asymmetric layout that allows for increased number of cells while maintaining matching. This asymmetric arrangement, combined with specific geometric relationships between pads and cells, enables phase and amplitude matching to be maintained even as the number of cells increases to provide higher output power.
Data Source
Figure 1
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Figure 3~4B
AI summary
An integrated HF-amplifÊer structure comprises in a first direction (FD) in the order mentioned: an input bond pad (IBP), a plurality of cells (CE1, CE2) being displaced with respect to each other in the first direction (FD), and an output bond pad (OBP). Each one of the cells (CE1, CE2) comprises an amplifier having an input pad (GP1, GP2), an active area (A1, A2), and an output pad (DP1, DP2). The active area (A1, A2) is arranged in- between the input pad (GP1, GP2) and the output pad (DP1, DP2), and the input pad (GP1, GP2), the active area (A1, A2), and the output pad (DP1, DP2) are displaced with respect to each other in a second direction (SD) substantially perpendicular to the first direction (FD). A first network (Nl) comprises first interconnecting means (Li, Ci; Li1, Li2, Ci1) to interconnect input pads (GP1, GP2) of adjacent ones of the plurality of cells (CE1, CE2), and extends in the first direction (FD). A second network (N2) comprises second interconnecting means (Lo, Co; Lo1, Lo2, Co1) to interconnect output pads (DPI, DP2) of adjacent ones of the plurality of cells (CE1, CE2), and extends in the first direction (FD). The first network (Nl) and the second network (N2) are constructed for obtaining an output signal (OS) at the output bond pad (OBP) having for all the interconnected cells (CE1, CE2) an equal phase shift and amplitude for a same input signal (IS) at the input bond pad (IBP). At particular bias and phase shift conditions the structure provides a Doherty amplifier with improvement of efficiency at power back off.