1. Introduction
The rapid increase of sensor nodes in modern sensory networks brings new challenges for sensor and processing platform design. To achieve real-time applications such as real-time video analysis, ultrafast sensors and neural networks should be implemented. Under this circumstance, in-sensor computing has been purposed, where part of the computing task is embedded in the sensor array and the processing time for the sensor and the neural network has been significantly reduced [1]. A conventional sensor array and an in-sensor computing array are shown in Fig. 1. Since the workload for the Analog-to-Digital Converter (ADC) between the sensor array and computing unit is reduced and the responsivity of each sensor acts as the weight for the neural network. The time to get output from the neural network is very short.