Abstract
This article presents a high-performance, low-power analog convolutional neural network (CNN) circuit integrated into a CMOS image sensor (CIS) for face detection applications. The main block of the proposed in-column analog CNN circuits is an analog multiplication-and-accumulation (MAC) circuit consisting of an operational transconductance amplifier-based switched capacitor circuit enabling the programmable weight function. With the proposed MAC, a 3-layer analog CNN processor is implemented into the column-parallel readout circuit in conventional CIS. Furthermore, for low-power CNN operations, we use a low-resolution analog-to-digital converter with the proposed nonlinear quantization method resulting in an increase in the accuracy of face detection from 92.8% to 98.75% at 120 frame rates with 2.8 V/1.5 V supply voltage. A prototype sensor with 160×120 effective image resolution was fabricated using a 110 nm CMOS image sensor process. The measurement results showed that the maximum power consumption was 0.57 mW and 4.02 mW at 1 and 120 frame rates, respectively.
Original language | English |
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Pages (from-to) | 61082-61090 |
Number of pages | 9 |
Journal | IEEE Access |
Volume | 11 |
DOIs | |
State | Published - 2023 |
Keywords
- CMOS image sensor
- convolutional neural networks
- face detection
- multiplication-and-accumulation
- nonlinear quantization