NbN circuits and packaging for 10 Kelvin IR focal plane array sensor signal processing

Infrared (IR) focal plane array (FPA) imaging signal processing circuits, b uilt in NbN and operating at 10 Kelvin, are presented. An ADC chip and digi tal signal processing chip are mounted on a 1.25 inch multi-chip module (MC M) with high bandwidth, low impedance interconnect. The populated MCM is de signed to be installed into a module housing for operation with the cryogen ic IR FPA. The 12-bit NbN SFQ counting ADC, previously used in a single chi p version of the IR focal plane array sensor test system, is now implemente d in an improved NbN process which includes a ground plane. Considerable at tention has been focused on reducing parasitic inductance to compensate for the high characteristic inductance of the NbN films. These design improvem ents increase operating margins and circuit yield and make the ADC more rob ust in the presence of external system noise. Data from a bit-serial subtra ction circuit to be used for pixel-by-pixel background subtraction is also presented. Finally, the design and electrical qualification of the physical package is described.