UWB Microwave Breast Screening with Self-Mixed Baseband Analog Signal Processing

This paper proposes an affordable and fast microwave imaging prototype using a time-domain baseband imaging technique with ultrawideband (UWB) impulse signals. Unlike traditional methods that sample the signal at RF, the signal of the proposed device is self-mixed to be downconverted to baseband, and then sampled using a real-time oscilloscope with a sub-GHz bandwidth. This noticeably simplifies the receiver and speeds up the signal acquisition. The required RF section of the receiver, including the low-noise amplifier (LNA) and self-mixer, is fabricated using a 65 nm CMOS integrated-circuit (IC) technology. Due to the low-frequency content of the received signals, traditional confocal imaging techniques cannot be directly used, and hence an energy-based imaging technique is also proposed. Experiments using a 3-D phantom with a skin layer show 0.5-1.8 cm localization accuracy in the detection of a 1 cm diameter tumor.