For the last three decades Moore’s law has provided the IC industry with smaller, faster, and cheaper transistors, facilitating integration of an increasing number of digital functions, thus propelling the growth of the semiconductor industry. However, this scaling trend poses greater challenges for analog and mixed-signal circuits that interface with real-world signals. The analog-to-digital interface is the performance bottleneck in most mixed-signal or communication systems.
We have reached an inflection point in the design of these interfaces: the “analog” designer must now know much more than analog design. While “calibration” techniques have been around for a decade or two, it is only recently that we have begun to incorporate a heavy content of digital signal processing to undo the analog imperfections. From this will arise a new generation of analog designers who must be as innovative in the analog domain as in the digital signal processing domain.
This talk presents a digitally-enhanced high-speed, high-resolution analog-to-digital converter (ADC). An all-digital calibration algorithm based on blind LMS that corrects for capacitor mismatch, residue gain error and op amp nonlinearity is introduced. Incorporated in a 12-bit pipelined ADC using an op amp with an open-loop gain of 25, the calibration leads to a measured SNDR of 62 dB at an input frequency of 91 MHz, the highest combination reported in the literature. Fabricated in 90-nm digital CMOS technology the ADC achieves a DNL of 0.78 LSB, an INL of 1.7 LSB.
Bibhu Datta Sahoo received the B. Tech. degree in electrical engineering from Indian Institute of Technology, Kharagpur, India, in 1998, the MSEE degree from University of Minnesota, Minneapolis, in 2000, and PhDEE degree from University of California, Los Angeles, in 2009.
From 2000 to 2006, he was with DSP Microelectronics Group at Broadcom Corporation, Irvine, CA, where he designed analog and digital integrated circuits for signal processing applications. In December 2008, he joined Maxlinear Inc., Carlsbad, CA, where he is involved in designing integrated circuits for CMOS TV tuners. His research interests include data conversion, signal processing, and analog circuit design.
He received the 2008 Analog Devices Outstanding Student Designer Award.