A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image SensorsReportar como inadecuado




A Dynamic Range Enhanced Readout Technique with a Two-Step TDC for High Speed Linear CMOS Image Sensors - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

School of Electronic Information Engineering, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China





*

Author to whom correspondence should be addressed.



Academic Editor: Vittorio M. N. Passaro

Abstract This paper presents a dynamic range DR enhanced readout technique with a two-step time-to-digital converter TDC for high speed linear CMOS image sensors. A multi-capacitor and self-regulated capacitive trans-impedance amplifier CTIA structure is employed to extend the dynamic range. The gain of the CTIA is auto adjusted by switching different capacitors to the integration node asynchronously according to the output voltage. A column-parallel ADC based on a two-step TDC is utilized to improve the conversion rate. The conversion is divided into coarse phase and fine phase. An error calibration scheme is also proposed to correct quantization errors caused by propagation delay skew within −Tclk~+Tclk. A linear CMOS image sensor pixel array is designed in the 0.13 μm CMOS process to verify this DR-enhanced high speed readout technique. The post simulation results indicate that the dynamic range of readout circuit is 99.02 dB and the ADC achieves 60.22 dB SNDR and 9.71 bit ENOB at a conversion rate of 2 MS-s after calibration, with 14.04 dB and 2.4 bit improvement, compared with SNDR and ENOB of that without calibration. View Full-Text

Keywords: CMOS image sensor; CTIA; wide dynamic range; two-step TDC; error calibration CMOS image sensor; CTIA; wide dynamic range; two-step TDC; error calibration





Autor: Zhiyuan Gao, Congjie Yang, Jiangtao Xu * and Kaiming Nie

Fuente: http://mdpi.com/



DESCARGAR PDF




Documentos relacionados