CCD versus CMOS
You will see a lot of banter going back and forth about CCD and CMOS imagers and a lot of comparisons between the two technologies. There are many strongly held opinions as to which technology is better. Some of these opinions are well founded and some are not. I'll take a neutral stand on the issue and say that CMOS is better suited for some applications and the CCD is better suited for others.
Before we get into which is better let's start with some simple definitions of each technology.
CCD - The Charge Coupled Device (CCD) is an array of metal oxide semiconductor (MOS) capacitors capable of detecting incident light and converting it to an electronic signal. Each capacitor, or pixel, is coupled to the next by a series of gates such that the electronic charge created in one pixel can be transferred to the next without loss. Ultimately, the charge in each pixel can be transferred to an output transistor where it is converted to a voltage, and then amplified and digitized through its associated readout electronics. The CCD, invented in 1969 by AT&T Bell researchers Willard Boyle and George Smith, was the first in the class of solid state imagers. The image quality and performance of these devices have made them the most ubiquitous image sensors in the world.
CMOS - Complementary Metal Oxide Semiconductor (CMOS) image sensors are comprised of an array of pixels where each pixel has its own amplifier. Often known as an Active Pixel Sensors because of the amplifier in each pixel, modern CMOS image sensors found their genesis in the pioneering work at Eric Fossum and others at the Jet Propulsion Laboratories (JPL). They have long held the promise of providing lower cost sensors due to the fact that they are constructed with the same tools and processes for much of today's semiconductor industry. These economies of scale are now starting to be realized and high performance CMOS image sensors are becoming ever more affordable and available. Decreasing cost and increasing performance will likely result in CMOS devices acting as a classic "disruptive technology" in the parlance of Clayton Christensen.
Before we get into which is better let's start with some simple definitions of each technology.
CCD - The Charge Coupled Device (CCD) is an array of metal oxide semiconductor (MOS) capacitors capable of detecting incident light and converting it to an electronic signal. Each capacitor, or pixel, is coupled to the next by a series of gates such that the electronic charge created in one pixel can be transferred to the next without loss. Ultimately, the charge in each pixel can be transferred to an output transistor where it is converted to a voltage, and then amplified and digitized through its associated readout electronics. The CCD, invented in 1969 by AT&T Bell researchers Willard Boyle and George Smith, was the first in the class of solid state imagers. The image quality and performance of these devices have made them the most ubiquitous image sensors in the world.
CMOS - Complementary Metal Oxide Semiconductor (CMOS) image sensors are comprised of an array of pixels where each pixel has its own amplifier. Often known as an Active Pixel Sensors because of the amplifier in each pixel, modern CMOS image sensors found their genesis in the pioneering work at Eric Fossum and others at the Jet Propulsion Laboratories (JPL). They have long held the promise of providing lower cost sensors due to the fact that they are constructed with the same tools and processes for much of today's semiconductor industry. These economies of scale are now starting to be realized and high performance CMOS image sensors are becoming ever more affordable and available. Decreasing cost and increasing performance will likely result in CMOS devices acting as a classic "disruptive technology" in the parlance of Clayton Christensen.
posted by Colin at
21:29
|
0 comments
