MEMS Mixed-Signal Package Crosstalk Reduction via DC Guard
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Solution Overview
Problem
Crosstalk between digital and sensitive analog signals in mixed-signal multi-chip packages, particularly within the electronic component package of microelectromechanical systems (MEMS), leads to errors in signal detection due to electromagnetic interference, which existing solutions do not adequately address.
Innovation Solution
The solution involves optimizing the layout and placement of bonding sites, including reducing the area of digital signal-bearing bond pads and using a bridging part in the lead frame to create a DC barrier between digital and analog signals, thereby minimizing crosstalk. This includes positioning digital signal-bearing chip pads away from analog bonding wires and using a DC guard to encircle signal-bearing bond pads, forming a semi-circle around the analog signal-bearing bond pad to reduce electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital and analog signals are integrated in the same package to enable mixed-signal processing, then functionality and versatility are improved, but crosstalk between digital and analog signals occurs causing electromagnetic interference
Solution Approach 1:
The patent divides the lead frame into distinct regions: a first region for digital signal bond pads and a second region for analog signal bond pads, with the analog region surrounded by a ground guard ring. This spatial segmentation separates digital and analog signals to prevent crosstalk while maintaining integrated mixed-signal processing functionality.
Solution Approach 2:
The ground guard ring acts as an intermediary barrier between the digital bond pads and analog bond pads. This ground shield mediates the electromagnetic fields, blocking crosstalk from digital signals from affecting analog signals while allowing both signal types to coexist in the same package.
2Area of stationary object
If bond pads are placed close to each other to minimize package size, then compactness is improved, but crosstalk between adjacent digital and analog signals increases
Solution Approach 1:
The patent applies different properties to different regions: the ground guard ring is positioned specifically around the analog bond pads to provide localized electromagnetic shielding. This local quality approach allows compact packaging while protecting sensitive analog signals from crosstalk only where needed.
Solution Approach 2:
The ground guard ring serves as an intermediary barrier that enables close spacing of bond pads without direct crosstalk. By inserting this ground shield between digital and analog bond pads, the design achieves compact packaging while maintaining signal integrity.
3Ease of manufacture
If no EMI protection is provided between bonding wires and bond pads, then manufacturing simplicity is improved, but crosstalk errors occur in sensitive analog signals
Solution Approach 1:
The ground guard ring acts as a passive intermediary shield that is integrated into the lead frame structure. It provides EMI protection for analog signals without requiring complex active shielding mechanisms, maintaining manufacturing simplicity while improving signal accuracy.
Solution Approach 2:
The ground guard ring is formed as an integral part of the lead frame structure during standard manufacturing processes. This self-service approach incorporates EMI protection without adding separate complex shielding components, maintaining ease of manufacture while protecting analog signals.
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 reduces crosstalk errors, with simulated results showing a reduction in crosstalk-induced voltage from 5mV to less than 0.5mV, improving the accuracy and reliability of MEMS device detection by minimizing electromagnetic interference between digital and analog signals.
Implementation Method 1
Crosstalk between strong digital signals and sensitive analog signals is one of these problems. Any electrical or magnetic interference may cause errors in these sensitive analog signals
Implementation Method 2
The bridging part and the two second bond pads form a semi-circle around the at least one first bond pad... at least one of the two second bond pads is to be coupled to a DC voltage to cause the bridging part to form a DC barrier
Data Source
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AI summary
The present invention relates to a mixed-signal multi-chip package and a method for reducing crosstalk in a mixed-signal multi-chip package. The package comprises a lead frame, a first die comprising MEMS structures and a digital die. The first die is configured to provide at least one analog signal in at least one analog chip pad of the first die. The digital die is configured to receive the at least one analog signal from the first die through at least one analog chip pad of the digital die. The at least one analog input chip pad of the digital die is coupled with the respective at least one analog output chip pad of the first die by a first bonding wire. The at least one digital die is configured to communicate with external circuitry using at least one digital signal-bearing signal exchanged via at least one first bond pad of the lead-frame. A bridging part encircles the at least one first bond pad at the side opposite of at least one signal-bearing lead configured to couple the respective at least one first bond pad towards external circuitry, forming a DC barrier between the at least one first bond pad and other parts residing inside the mixed-signal multi-chip package. The bridging part extends to further encircle a lateral area comprising at least one digital signal-bearing chip pad of the digital die and digital signal-bearing bonding wires coupling the at least one first bond pad and the at least one digital signal-bearing chip pad.