Interleaved CIC Filter for Shared MEMS Sensor Signal Decimation
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Solution Overview
Problem
MEMS sensors face challenges in processing multiple signals efficiently due to the need for duplicate processing circuitry, which increases chip area and power consumption, especially in miniature devices with multiple sensors like accelerometers and microphones.
Innovation Solution
An interleaved cascaded integrator-comb (CIC) filter is used to process interleaved signals, which buffers and selectively processes signal portions, allowing a single integrator and comb filter to handle multiple signals at a reduced clock rate, thereby reducing duplication of circuitry and power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate processing circuitry is used for each sensor signal, then signal processing quality is maintained, but chip area and power consumption increase
Solution Approach 1:
The patent combines multiple sensor signal processing paths into a single shared CIC filter structure. Multiple interleaved signals from different sensors are processed through common integrator and comb filter stages, eliminating the need for separate processing circuitry for each sensor while maintaining signal processing quality through proper interleaving and decimation techniques
Solution Approach 2:
The CIC filter structure is designed to handle multiple types of sensor signals universally. The same integrator and comb filter circuitry can process signals from accelerometers, microphones, and other sensors by accepting interleaved input streams, making the processing circuitry multi-functional rather than dedicated to a single sensor type
2Reliability
If separate processing circuitry is used for each sensor signal, then signal processing quality is maintained, but power consumption increases
Solution Approach 1:
The patent combines multiple sensor signal processing paths into a single shared CIC filter structure. Multiple interleaved signals from different sensors are processed through common integrator and comb filter stages, eliminating the need for separate processing circuitry for each sensor while maintaining signal processing quality through proper interleaving and decimation techniques
Solution Approach 2:
The CIC filter structure is designed to handle multiple types of sensor signals universally. The same integrator and comb filter circuitry can process signals from accelerometers, microphones, and other sensors by accepting interleaved input streams, making the processing circuitry multi-functional rather than dedicated to a single sensor type
3Measurement precision
If all sensor signals are processed at the original high clock rate, then processing accuracy is maintained, but power consumption and computational load increase
Solution Approach 1:
The patent applies preliminary decimation by interleaving multiple sensor signals into a single stream at the input stage. This preliminary action allows the subsequent CIC filter stages to operate at a reduced clock rate while maintaining processing accuracy, as the interleaved structure preserves all necessary signal information in a compact format that can be processed more efficiently
Solution Approach 2:
The patent changes the clock rate parameter from the original high frequency to a reduced frequency after the initial interleaving stage. The CIC filter structure enables this parameter change while maintaining processing accuracy through its inherent decimation capability, which reduces the sampling rate without losing essential signal information
4Productivity
If duplicate processing circuitry is used for each sensor, then signal processing capability is sufficient, but device complexity increases
Solution Approach 1:
The patent combines multiple sensor signal processing paths into a single shared CIC filter structure. Multiple interleaved signals from different sensors are processed through common integrator and comb filter stages, eliminating the need for separate processing circuitry for each sensor while maintaining signal processing quality through proper interleaving and decimation techniques
Solution Approach 2:
The CIC filter structure is designed to handle multiple types of sensor signals universally. The same integrator and comb filter circuitry can process signals from accelerometers, microphones, and other sensors by accepting interleaved input streams, making the processing circuitry multi-functional rather than dedicated to a single sensor type
Data Source
AI summary
An interleaved cascaded integrator-comb (“CIC”) filter receives an interleaved sensor output signal, including a plurality of digitized sensor signals at an input clock rate. An integrator of the interleaved CIC filter processes the interleaved signal to output an integrated interleaved signal. A downsampler of the interleaved CIC filter buffers portions of the integrated interleaved corresponding to a decimation rate for the interleaved signal. The portions of the signals are provided to a comb filter, which outputs a decimated interleaved signal.