A 0.55 THz Near-Field Sensor With a $\mu \text{m}$ -Range Lateral Resolution Fully Integrated in 130 nm SiGe BiCMOS

This paper presents a room-temperature operating superresolution terahertz (THz) planar near-field solidstate sensor breaking the diffraction limit. Contrary to classical superresolution imagers implemented in the optical domain, the sensor features inbuilt illumination, evanescent-field sensing, and detection on a single chip, eliminating the need for any external optics. Both metallic and dielectric objects can be imaged with the sensor and mapped into a monotonic sensor response. It is operated around 533-555 GHz in 130 nm SiGe HBT technology and is capable of resolving structural details with a μm-range resolution and a high response of up to 21.7 μA with no amplification stages in the readout path. Here, the stop-band characteristic of a differentially driven 3-D split-ring resonator with high spatial confinement of evanescent surface fields is exploited as an object-tunable transmission modulator inserted in-plane between a tunable 3-push Colpitts oscillator and a broadband power detector. A separate antenna-coupled oscillator breakout provides a radiated power of up to 45 μW (-13.4 dBm). This paper further demonstrates the 2-D scanned superresolution image with a remarkable SNR of up to 40 dB for the sensor operating at dc.