Low-Noise Readout Integrated Circuit for Terahertz Array Detector

Abstract

In the field of terahertz (THz) imaging applications, using a 0.18- μ m CMOS process, a ${\text{1}}\times {\text{16}}$ low-noise readout integrated circuit (ROIC) is developed for a ${\text{1}}\times {\text{64}}\,{\text{Nb}}_{5}{\text{N}}_{6}$ microbolometer array detector. This circuit consists of a digitally programmable current digital-to-analog converter and an amplifier module, which are responsible for biasing the microbolometer and amplifying its output signals with minimum added noise, respectively. Test results show that the ROIC achieves an average gain of ∼47 dB and a voltage noise spectral density of $\sim {\text{9.34}} \;{ \text{nV}/ \surd {\text{Hz}}}$ at 10 kHz, which meet the requirements for the THz array detector. Moreover, the responsivity of the Nb5N6 microbolometer detector is −580 V/W, and the corresponding noise equivalent power is ${{\text{17}} \text{pW}/ \surd \text{Hz}}$ . Together with the ROIC, the ${\text{1}}\times {\text{64}}\,{\text{Nb}}_{5}{\text{N}}_{6}$ microbolometer array detector is preliminarily used for THz imaging applications. The imaging results prove that the ROIC can be used with the detector to develop an efficient and low-cost THz imaging system.