Concurrent-Mode CMOS Detector IC for Sub-Terahertz Imaging System.

Area of Science:

• Electrical Engineering
• Applied Physics
• Materials Science

Background:

• Sub-terahertz imaging requires sensitive and high-resolution detectors.
• Existing CMOS detectors face limitations in signal coupling and noise performance.
• Improving detector efficiency is crucial for advancing terahertz (THz) applications.

Purpose of the Study:

• To propose and characterize a novel CMOS detector for high-quality sub-terahertz imaging.
• To enhance output-signal coupling and reduce noise in CMOS-based detectors.
• To achieve superior signal-to-noise ratio (SNR) for improved THz imaging capabilities.

Main Methods:

• Design of a CMOS detector incorporating a cross-coupling capacitor for DC bias isolation and phase shifting.
• Electromagnetic (EM) simulation to verify circuit layout and phase coupling.
• Fabrication using TSMC 0.25-μm CMOS process.
• Performance evaluation using a 200-GHz gyrotron source.

Main Results:

• Achieved a voltage responsivity of 14.13 MV/W and a noise-equivalent power (NEP) of 34.42 pW/√Hz.
• Demonstrated high detection performance capable of resolving a 2-mm line width.
• Obtained an SNR of 49 dB for THz imaging, a 9 dB improvement over previous designs.

Conclusions:

• The proposed CMOS detector significantly enhances sub-terahertz imaging quality.
• The novel design overcomes limitations in signal coupling and noise, offering superior performance.
• This advancement paves the way for more effective THz imaging systems.