We describe a 2-D fully differential Readout Integrated Circuit (ROIC) designed to convert the photocurrents from an array of differential metal-semiconductor-metal (MSM) detectors into voltage signals suitable for digitization and post processing. The 2-D MSM array and CMOS ROIC are designed to function as a front-end module for an amplitude modulated/continuous time AM/CW 3-D Ladar imager under development at the Army Research Laboratory. One important aspect of our ROIC design is scalability. Within reasonable power consumption and photodetector size constraints, the ROIC architecture presented here scales up linearly without compromising complexity. The other key feature of our ROIC design is the mitigation of local oscillator coupling. In our ladar imaging application, the signal demodulation process that takes place in the MSM detectors introduces parasitic radio frequency (rf) currents that can be 4 to 5 orders of magnitude greater than the signal of interest. We present a fully-differential photodetector architecture and a circuit level solution to reduce the parasitic effect. As a proof of principle we have fabricated a 0.18 μm CMOS 32x16 fully differential ROIC with an array of 32 correlated double sampling (cds) capacitive transimpedance amplifiers (CTIAs), and a custom printed circuit board equipped to verify the test chip functionality. In this paper we discuss the fully differential IC design architecture and implementation and present the future testing strategy.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.