A readout IC for an uncooled microbolometer infrared FPA with on-chip self-heating compensation in 0.35 lm CMOS Daniel Sva ¨rd • Christer Jansson • Atila Alvandpour Received: 15 February 2013 / Revised: 12 July 2013 / Accepted: 29 July 2013 / Published online: 17 August 2013 Ó Springer Science+Business Media New York 2013 Abstract This paper describes a readout integrated cir- cuit architecture for an infrared focal plane array intended for infrared network-attached video cameras in surveil- lance applications. The focal plane array consists of 352 9 288 uncooled thin-film microbolometer detectors with a pitch of 25 lm, enabling ambient temperature operation. The circuit features a low-noise readout path, detector resistance mismatch correction and a non-linear ramped current pulse scheme for the electrical biasing of the detectors in order to relax the dynamic range require- ment of amplifiers and the ADC in the readout channel, imposed by detector process variation and self-heating during readout. The design is implemented in a 0.35-lm standard CMOS process and two versions of a smaller 32 9 32-pixel test chip have been fabricated and measured for evaluation. The latest test chip achieves a dynamic range of 97 dB and an input-referred RMS noise voltage of 6.4 lV yielding an estimated NETD value of 26 mK with f/1 optics. At a frame rate of 60 FPS the chip dissipates 170 mW of power from a 3.4 V supply. Keywords Readout integrated circuit  Uncooled microbolometer  Infrared imaging  High-resolution data conversion  Self-heating compensation  Bias heating compensation 1 Introduction Thermal infrared imaging has received much research attention in recent time. It has several applications within different industries, particularly in military, automotive, process and security/surveillance industries. While IR imaging has been available for a long time, it has been in the form of large, bulky photon detector systems in the need for active cooling of the infrared detectors in order to operate properly. This fact has made such imaging systems expensive and of little use in many application areas. With the advent of the thin-film microbolometer detector [1–3], the requirement of cooling the detectors to achieve high performance was removed and this opened up the oppor- tunity to create less expensive and smaller systems oper- ating without cooling while having good enough performance for all but the most extreme applications [4]. In this paper a readout integrated circuit (ROIC) archi- tecture for a 352 9 288-pixel infrared focal plane array (IRFPA) using microbolometers with a pitch of 25 lm is presented. The design is aimed toward a network-attached infrared video camera for use in visual surveillance appli- cations, where infrared imaging can help in conditions where normal imaging would be limited, such as in low light, total darkness, fog or where an object is masked visually but not thermally by another object. This appli- cation requires the system to function in ambient temper- atures ranging from -10 to 70 °C, which imposes very strict requirements on the electrical biasing of the mic- robolometer detectors. The focus of the paper is on the biasing of the detectors to relax the required dynamic range of the ROIC due to process variation and self-heating; and on the low-noise readout channel used to digitize the detector output signals. A well designed scheme for biasing of the microbolometer D. Sva ¨rd (&)  C. Jansson  A. Alvandpour Department of Electrical Engineering, Linko ¨ping University, Linko ¨ping, Sweden e-mail: svard@isy.liu.se 123 Analog Integr Circ Sig Process (2013) 77:29–44 DOI 10.1007/s10470-013-0116-9