Human Interface Group

◈ CMOS image sensor 

    ◇ Introduction


- As analog image capturing devices using a film have been replaced by digital devices such as charge-coupled devices(CCDs)
and complementary metal-oxide semiconductor(CMOS) image sensors, imagers was miniaturized and capable of performing
the real-time image processing. Nowadays, digital imagers are widely used in many applications such as mobile devices,
industrial robots, and medical electronics. Especially, CMOS image sensors are increasingly adopted because they have
advantages of low-power consumption, high-resolution pixel and circuit integration capabilities.

- Image sensor group in IELAB has been researching low power, wide dynamic range, low noise, high speed, and high
bit-depth technologies in CMOS image sensors for from consumer to medical applications.

    ◇ Research area
      · Low-power and high-speed CMOS image sensor
          - Low-power, small-area, and high-speed column-parallel ADC
          - Wide dynamic range readout technique

      · Wafer-scale CMOS X-ray detector
          - High-resolution column-parallel ADC
          - 3-side buttable readout architecture
          - Reference, bias, and signal transmission techniques for large-sized IC

      · Smart CMOS image sensor
          - Compressed sensing CMOS image sensor

CMOS image sensor

Wafer-scale CMOS X-ray detector

    ◇ Research results
      · 1.92 Mpixel CMOS image sensor with integrating type SA ADC and switched-power technique
          - Process: 0.13-μm 1P4M CIS
          - Chip size: 5 mm × 7 mm
          - Pixel size: 2.25 μm × 2.25 μm
          - Resolution: 1600(V) × 1200(H)

          - ADC resolution: 10-bit
          - Max. frame rate: 150 frames/s

Full frame image captured at 60 frames/s

Chip Microphotograph

    ◇ Research results
      · 0.3 Mpixel CMOS image sensor with 12b two-step ADC
          - Process: 90-nm 1P4M CIS
          - Chip size: 5 mm × 5 mm
          - Pixel size: 3.5 
μm × 3.5 μm
          - Resolution: 640(V) × 480(H)
          - ADC resolution: 12-bit
          - Max. frame rate: 300 frames/s

Captured Image

Block diagram of image sensor

    ◇ Research results
      · CMOS X-ray detector
          - Process: 0.35-μm 1P4M CMOS process
          - Sensitivity: 0.11 V/mR
          - MTF: 32.8% at 4.86 lp/mm
          - ADC resolution: 14.3 bits
          - Max. frame rate: 60 frames/s

Captured images (line pair, characters, package)

Chip Microphotograph

◈ Bio-Signal Monitoring System 

    ◇ Introduction
         - In recent years, with the rapid growth of portable electronics market, the demand for a human-computer interface (HCI)
          has continued to increase We have been developed readout front-end for the HCI. Our goal is to create bio-sensors with
          high performance and low power consumption.

    ◇ Research area
      · Bio-sensors 

    ◇ Research results

      · EMG readout front-end
          - Process: 0.18 μm CMOS
          - Area: 1.2 × 1.1 
          - CMRR: 105 dB
          - Power dissipation: 19 

Chip Microphotograph

Extracted EMG signal from readout front-end

◈ 3-D Ultrasound Imaging System

    ◇ Introduction


- 3-D ultrasound imaging systems are increasingly used for medical diagnosis such as fetal examination, assessment of cardiac
function, and tumor localization, etc. For implementation of high-resolution 3-D ultrasound imaging systems, 2-D active
capacitive micro-machined ultrasound transducer (CMUT) array have been interest over the year. We have researched the
2-D active CMUT array based 3-D ultrasound imaging systems with high-resolution and high frame rate.

    ◇ Research area

      · 2-D active capacitive micro-machined ultrasound transducer (CMUT) array
      · High-performance data acquisition(DAQ) system for ultrasound imaging system

    ◇ Research results

      · Three-side buttable 16×16 active CMUT array
          - Fully-integrated 16×16 transceivers with transmitting beamforming
          - Programmable beamforming methods
          - 159 % frame rate enhancement

Measured output waveforms of fabricated active CMUT array

Measured input referred pressure noise

Acquired 3-D ultrasound image by using
spring phantom with 0.6 mm diameter

    ◇ Chip
          - Process : 120V 0.35-μm BCD process
          - Area : 7 mm × 4.4 mm
          - Input referred pressure noise : 0.6 mPa/√Hz
          - Output voltage of HV pulse : 120V
          - Minimum delay control step : 5ns

◈ Touch Screen System

    ◇ Introduction


- Capacitive touch screens are widely used in mobile devices such as tablets, note-books, and smart phones. As people
require capacitive touch screen system with high-sensitivity, touch screen systems demand high-accuracy read-out circuits.
We have researched noise reduction methods and analog-to-digital converters for high-accuracy read-out circuits.

    ◇ Research area

      · Read-out circuits for capacitive touch screen system

    ◇ Research results

      · 3.5-inch add-on type capacitive touch screen system
          - Spatial resolution of TSP: 7×9
          - Pattern pitch: 8mm
          - Measuring type: mutual capacitance
          - Compensation of capacitance variation

(a) before compensation

(b) after compensation

Touch screen system

3-D image of touched point

    ◇ Research results

      · 13.3-inch on-cell type capacitive touch screen system
          - Spatial resolution of TSP: 53×29
          - Pattern pitch:5.5mm
          - Measuring type: mutual capacitance
          - Differential sensing method for noise reduction

Display system with an on-cell
capacitive TSP

2-D image of touched point

3-D image of touched point