The goal is to build ultrasonic radars to detect small objects. This project will focus on designing circuits to change phases to each transducer to control the scanning directions. An ultrasonic sensor (transducer, used as both transmitter and receiver) sends an ultrasonic pulse. The mechanical wave is reflected back from any objects and detected by the transducer. The time delay in the pulse-echo can be used to calculate the distance of the objects. The use of a number of transducers to form a phased array has following advantages: increasing the signal to noise ratio; increasing detection distance, having much narrow beam to have higher direction resolution, and scanning all directions automatically by changing phase of each transducer electronically. By scanning all directions, the ultrasonic phased array will generate 3D images like a radar.