CCD Primer

Bracket Pulsing
CCD Grading
Cosmic Rays
Dark Current
Deep Depletion CCD
Detection Modes
Dual Capacity Mode
Dual Readout Mode
Dynamic Range
Etaloning in CCDs
UV Extension
Fiber Optics
Flat Fielding
Full Well Capacity
Image Calibration
Imager Architectures
Image Intensifiers
Kinetics Mode
Matching Resolution
MPP Mode
Noise Sources
On-chip Multiplication Gain
Open Poly CCD
Optical Window
Quantum Efficiency
Readout vs Frame Rate
Reducing Dark Current
Saturation/ Blooming
Signal to Noise Ratio
Spurious Charge
XP Cooling


Electron-Multiplying (EM) Gain

Formerly referred to as "on-chip multiplication gain", this technology enables multiplication of charge (i.e., electrons) collected in each pixel of the CCD's active array. Secondary electrons are generated via an impact-ionization process that is initiated and sustained when higher-than-typical clock voltages (up to 50 V) are applied to a special extended portion of the CCD's serial register.

The level of EM gain can be controlled by either increasing or decreasing the voltage; the gain is exponentially proportional to the voltage. Multiplying the signal above the read noise of the output amplifier enables ultra-low-light detection at high operation speeds. EM gain can exceed 1000x.

It is possible to adapt this technology to all current CCD architectures. The illustration below depicts a frame-transfer device.

ccd image

Some cameras with EM gain utilize two output amplifiers: (1) an EM gain amplifier that enables the camera to be used for low-light, high-speed applications and (2) a traditional amplifier for wide-dynamic-range applications.