Past Seminars:
Robert C. Schell
CISL at Columbia University
Date: 2:30pm, Friday, Nov. 30, 2007
Place: 414 CEPSR
Title:
A Clockless ADC/DSP/DAC System with Activity-Dependent Power
Dissipation and No
Aliasing
A fully clockless
programmable ADC/DSP/DAC system is realized in a 90nm CMOS process and
uses a 1 V supply. The 8-bit voiceband system operates in continuous
time, occupies 1.7 mm2, has no aliasing and achieves an in-band SDR of
47-62 dB and a power dissipation of 0.25 to 1.7 mW, depending on input
activity.
(Based on Bob's work to be presented at ISSCC 2008)
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Junhua Shen
CISL at Columbia University
Date: 2:00pm, Friday, Nov. 2, 2007
Place: Interschool Lab, 7th floor, CEPSR
Title: 0.5V
8-Bit 10Msps Pipelined ADC in 90nm CMOS
This talk presents
a pipelined analog to digital converter (ADC) operating from a 0.5-V
supply voltage. The ADC uses true low-voltage design techniques that do
not require any on-chip supply or clock voltage boosting. The switch
OFF leakage in the sampling circuit is suppressed using a cascaded
sampling technique. A front-end signal-path sample-and-hold amplifier
(SHA) is avoided by using a coarse auxiliary sample and hold (S/H) for
the sub-ADC, and by synchronizing the sub-ADC and pipeline-stage
sampling circuit. A 0.5-V operational transconductance amplifier is
presented that provides inter-stage amplification with an 8-bit
performance for the pipelined ADC operating at 10 Msps. The chip was
fabricated on a standard 90nm CMOS technology and measures 1.2 mm by
1.2 mm. The prototype chip has 8 identical stages and stage scaling was
not used. It consumes 2.4 mW for 10-Msps operation. Measured peak SNDR
is 48.1 dB and peak SFDR is 57.2 dB for a full-scale sinusoidal input.
Maximal integral nonlinearity (INL) and differential nonlinearity (DNL)
are 1.19 and 0.55 LSB respectively.
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Ari Klein
CISL at Columbia University
Date: 2:00pm, Friday, Oct. 26, 2007
Place: Interschool Lab, 7th floor, CEPSR
Title:
INSTANTANEOUSLY COMPANDING DIGITAL SIGNAL PROCESSORS
This talk presents
an extension of instantaneous companding (compressing and expanding) to
digital signal processors (DSPs). Companding has been used for many
years in non-dynamical channels, but the dynamical nature of DSPs
causes output distortion in standard implementations of companding,
where a compressor and expander are used at the input and output,
respectively, without additionally modifying the DSP. In contrast, the
proposed technique combines input compression, output expansion, and
application of nonlinear functions internal to the DSP, all in a manner
transparent to the input-output characteristics of the DSP and its A/D
interfaces, thus eliminating distortion in the final
analog output. As a result, all the signals involved span most of the
available bits, resulting in significant improvement in quantization
errors and signal-to-noise-plus-distortion ratios over a large input
range. The theory is supported by simulation and subjective listening
tests.
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Professor Jri Lee
Electrical engineering at National Taiwan University
Date: 2:00pm, Thursday, Oct. 18, 2007
Place: EE Conference Room 1312 S.W. Mudd
Title: High-Speed IC
Designs for Future Communication Systems
Recent developments
on wireless and wireline communications have pushed the operation
freuqency toward tens of gigahertz. This talk presents novel
high-speed techniques for different applications as well as
their silicon realizations, comprising a 75-GHz PLL, a 20-Gb/s
burst-mode CDR, and a 60-GHz RF front end. Future design trends
for high-speed circuits are also included.
Bio: Jri Lee received the B.Sc. degree in electrical engineering
from National Taiwan University (NTU), Taipei, Taiwan in 1995,
and the M.S. and Ph.D. degrees in electrical engineering from
the University of California, Los Angeles (UCLA), both in 2003.
His current research interests include high-speed wireless and
wireline transceivers, phase-locked loops, and data converters.
He has been an Assistant Professor in electrical engineering at
National Taiwan University since 2004. Prior to that, he had
military service for 2 years and worked in the industry/research
institute for 3 years. Dr. Lee received the Beatrice Winner Award
for Editorial Excellence at the 2007 ISSCC, and NTU Outstanding
Teaching Award in 2006. He is currently serving in the technical
program committees of International Solid-State Circuits Conference
(ISSCC) and Asian Solid-State Circuits Conference (A-SSCC).
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