English 
Chinese Introduction
As mobile devices and voice-controlled systems evolve, so do the performance requirements of their acoustic sensors. MEMS (Micro-Electro-Mechanical Systems) microphones have become the standard for embedded audio, prized for their small form factor, integration ease, and consistent quality. But beyond transducer performance, one factor plays an increasingly critical role in determining real-world results: the chip-scale package.
At SiSTC, we understand that package structure directly affects the acoustic transfer function of a MEMS microphone—especially as applications demand precision across broader frequency ranges. This article explores how advanced modeling approaches are transforming how we design and optimize MEMS microphone packaging for both low- and high-frequency performance.
Why Package Modeling Matters
Traditional modeling of MEMS microphone packages relied on lumped equivalent circuit models to predict acoustic behavior. While effective at low and mid frequencies, these simplified models fall short in simulating high-frequency resonances, pressure gradients, and mechanical interactions within the full acoustic path.
To address this, researchers have adopted a more advanced approach: the distributed parameter model.
What Is a Distributed Parameter Model?
Unlike lumped models that treat acoustic parameters as concentrated at discrete points (resistance, compliance, inertia), a distributed parameter model spreads those properties over the entire geometry of the package.
This enables:
- 🧠 High-resolution simulation of acoustic wave propagation
- 🎯 More accurate frequency response curves, especially above 10 kHz
- ⚙️ Visualization of how structural changes affect mechanical and acoustic behavior simultaneously
Key Findings from the Model
The study revealed how three major package features impact the acoustic transfer function and overall sensitivity of MEMS microphones:
🔘 1. Sound Port (Acoustic Hole) Size
- Influences the cutoff frequency and impedance
- Larger holes reduce front-chamber resistance but may introduce resonance peaks
🏠 2. Front Chamber Volume
- Affects low-frequency response and acoustic stiffness
- Tuning volume size helps extend flatness in the 100–1000 Hz range
📦 3. Back Chamber Volume
- Impacts diaphragm displacement and damping characteristics
- Key for maintaining linear response at higher SPLs
Together, these parameters shape the directionality, frequency response, and signal-to-noise ratio of the microphone system.
Design Implications for SiSTC MEMS Microphones
At SiSTC, our MEMS microphone packages are designed with both electrical and acoustic-mechanical co-optimization in mind. We apply insights from distributed parameter modeling to:
- Optimize port and cavity geometry for specific use cases
- Minimize frequency distortion at high SPLs
- Ensure robust performance in mobile, automotive, and industrial environments
- Deliver tighter SNR tolerances across production batches
🔍 Explore our MEMS microphone series here:
👉 https://sistc.com/product-category/mems-microphone/
Application Areas That Demand Advanced Modeling
- 🎧 Smartphones and TWS earbuds — tight space, broad frequency spectrum
- 🚘 In-vehicle voice assistants — variable SPLs and unpredictable noise environments
- 🧠 Edge AI and far-field voice capture — require directional sensitivity and extended dynamic range
- 🧪 Laboratory and measurement microphones — need low distortion and modeled response accuracy
Conclusion
As MEMS microphones take on more mission-critical roles in modern devices, chip-scale package design is no longer a back-end concern—it’s a performance driver. Through distributed parameter modeling, designers can now fine-tune structural parameters to unlock optimal frequency response, sensitivity, and directional behavior.
At SiSTC, we integrate this modeling approach directly into our microphone development cycle to ensure every product meets the demands of its intended acoustic environment.
📘 Reference: Modelling of a Chip Scale Package on the Acoustic Behavior of a MEMS Microphone, AES 147th International Convention.
