Q: What is ACS?

A:  ACS is a patented, fundamentally different form of image sensor architecture that enables higher dynamic range with virtually no Fixed Pattern noise generated at the pixel as occurs with Active Pixel Sensors (APS). Additionally, increased Fill Factor further increases sensitivity and dynamic range. It is an elegant yet simple technology, enabling sensors with smaller pixels, excellent image quality, higher speeds, and lower overall cost.

Q: What is XtremePIX?

A:  XtremePIX is the next generation of ACS.  Pixels with this technology can have as little as one-half (1/2) of a transistor inside each.  This is nearly 1/6 of the circuitry of a typical 3 transistor APS imager!  This means that given the same size pixel and process technology as an APS, the XtremePIX pixel will have over twice the Fill Factor (Light sensitive area to total pixel area), resulting in;

• Greater Dynamic Range
• Sensitivity
• Smaller Pixels
• Higher Resolution 

Additionally, the technology enables true Correlated Double Sampling (CDS), not pseudo CDS as provided by most APS designs.  XtremePIX sensors have lower noise, which further improves sensitivity and dynamic range.

Q: Are there other advantages with XtremePIX?

A:  Yes, and it's plenty;

• New Distributed 12 bit Analog to Digital Converter, we call is D/AD™
• In Pixel binning mode to multiply sensitivity for night time video capture
• Enables Extended Dynamic Range Capture by the camera
• Full frame video at 30 fps (depends on resolution and configuration)
• and more

The bottom line is that XtremePIX Sensors combine the best performance features of a CCD with the benefits of CMOS.

Q: Are these  sensors made using CMOS?

A:  Yes.  The image sensors are made using standard CMOS semiconductor manufacturing processes.

Q: Why don't CMOS APS sensors have CCD like performance?

A: Typical APS Sensors have many fundamental drawbacks.  Each pixel in an APS sensor includes within it an open loop amplifier that: (1) takes away from the available area to collect light (lowering the signal),  (2) has varying gain and offset that creates Fixed Pattern Noise, (3) limits the operating speed of the pixel array, and (4) limits the ability to shrink the pixel to compete effectively against CCD's.  The bottom line is that APS Sensors must make tradeoffs between pixel size, resolution, image quality, and speed.  For example, a high res. 14 MP+ APS image sensor operates at very low speeds.  Small pixel APS Sensors operate at video rates but have poor image quality, and so on.  See the ACS vs. APS primer for more information.

Q: What about CID Sensors?

A: CID Sensors are a passive array of pixels, and have no amplifier per pixel.  They use a Photogate structure like a CCD, however charge is not shifted out like a CCD.  Instead each pixel in a column is connected together on a common bus.  The pixels are not buffered, thus the signal from each pixel is divided by the number of pixels connected in a column, resulting in weak signal.  CIDs are very radiation hard and do have true random access and non-destructive read capability, making them a great choice for some niche applications.

Q: What's wrong with CCDs, after all they provide great image quality?

A: CCDs are good imaging devices.  However, a CCD can not easily integrate timing, control, A/D, or image processing logic on the same silicon die.  They require an interface chip to operate, typically consume high power, and sometimes require odd voltages.  This means that imaging systems using a CCD are typically more expensive, physically larger in size, and consume more power. 

ACS® is a registered trademark of Panavision Imaging, LLC, Homer, NY

Active Column Sensor™,  XtremePIX™ are trademarks of Panavision Imaging, LLC