IEEE Solid-State Circuits Magazine - Spring 2014 - 85

"B" Influence Zone

"A" Influence Zone

-2

Electronic Potential
Boundary Between
9.8E-01
7.4E-01
Influence Zones
6.0E-01
2.6E-01
2.0E-01
0
-2.2E-01
X

* A and B Alternate High/Low
* Light Synchronized with A/B Clock
* When A Is High, Most Electrons Captured by A
* When B Is High, Most Electrons Captured by B
* Changes Never Transferred from A to B
(a)

450
400
350
300
250
200
150
100
50
0

Z Distance (cm)

(b)

Figure 5: Microsoft's 3-D depth and active IR imaging.

the vicinity of another NFC device,
an operation known as "tap and go."
The focus of Mediatek's demo is the
adoption of a single receiver with
one reconfigurable PLL to support
all NFC modes for compact die area.
MediaTek's NFC architecture (Figure 6) enabled using the proximitycoupled-device (PCD) receiver with
reconfigurable PLL to support proximity-inductively coupled card (PICC)
operations, including joint data type
detection, and to leverage it to significantly reduce the PCD low card power
polling mode current consumption.
The radio supports cm-range communication at 13.6 MHz, achieved stateof-art performance in one-third of
area (1.1 mm2) in 0.11-μm CMOS.

Princeton and UC Berkeley and
Davis's 3-D Gesture Sensing
Princeton University's
3-D -Gesture Based on
Extended-Range -Capacitive Sensing
The challenge of 3-D capacitive sensing
is achieving sensitivity at 20-30 cm
distances when sensing the small
capacitive perturbations caused by
user interaction with sensing electrodes. This distance is achieved via
two approaches. First, capacitance
sensing is performed via frequency

modulation, and the sensitivity of
frequency readout is enhanced by
high-Q oscillators capable of filtering
noise sources in the readout system
as well as stray noise sources from
display coupling. Second, the capacitance signal is enhanced by eliminating electrostatic coupling between the
sensing electrodes and surrounding
ground planes (Figure 7). The total
power consumption is fewer than 20
mW (475 μW for frequency readout,
19 mW for OP driver). The readout
time is 500 μs per channel, enabling a
240-Hz scan rate.

UC Berkeley and Davis's 3-D
-Ultrasonic Gesture Recognition
Gesture interaction is a natural way
to control your devices. Unfortunately, optical 3-D range finders are
too large, sunlight sensitive, and
power hungry to be incorporated in
an energy-constrained environment
such as a mobile device. Gesture
recognition using sound is an attractive candidate to overcome these difficulties. The demonstrated system
(Figure 8) transmits a short pulse of
ultrasound into the environment and
then listens for echoes from objects
within 1 m. The system automatically tunes to the resonant frequency
of the MEMS ultrasound transducers,

which each working as a transmitter and receiver. System power consumption is 400 μW at 30 frames/s,
or 14 μJ/measurement.

Sharp, Kobe University and
Panasonic's Large-Area Touch UI
Sharp's 240-Hz, 143 × 81 Mutual--
Capacitance Touch-Sensing
Analog Front-End IC
Sharp's realization of mutual capacitance touch-sensing systems features an unified touch UI for all sizes
of displays from 4 in up to 100 in, a
fine-pen handwriting without additional pen digitizer, and strong immunity against LCD noise. An analog
front-end (AFE) IC capable of driving and sensing a 143 × 81 mutualcapacitance sensor is developed in
0.18-μm 1P5M CMOS (Figure 9). A 32and a 70-in system are demonstrated
with the use of the AFE and a 7-μm
thickness copper mesh sensor technology. The 70-in system is built up
from three AFEs, a DBE implemented
in an FPGA, 6.25-mm channel pitch
248 × 140 metal mesh sensor laminated to a 1.9-mm thickness cover
glass, and mounted on a FHD LCD
with 3.24-mm air gap, with an SNR
over 37 dB for 1-mm diameter stylus
is attained in either system.

IEEE SOLID-STATE CIRCUITS MAGAZINE

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Table of Contents for the Digital Edition of IEEE Solid-State Circuits Magazine - Spring 2014