I

I2C (inter-integrated circuit)

A serial interface developed by Philips Electronics. The I2C, pronounced “I-squared-C” or “I-two-C,” allows information transfer between ICs by using two signal lines that are SCL (serial clock) and SDA (serial data) lines. The I2C is used in electronic appliances, cell phones, digital cameras, and audio equipment, for example, when connecting a low-speed (several hundred kilohertz) peripheral device to microcontrollers.

Integration capacitance

Because signal processing is not easy in current-output type NMOS linear image sensors, their output is converted to a voltage output that has low noise and is easier to process by using an inverted input op amp circuit with a feedback capacitance (Cf) added. This feedback capacitance is called the integration capacitance. Periodically resetting the integration capacitance provides a voltage output (V = Q/Cf) converted from an electric charge (Q). The smaller the integration capacitance, the larger the output voltage will be.

Integration time

In image sensor operation, the electric charge generated by light entering in a given time is accumulated and collected to create a signal. The length of this time during which light enters the image sensor is called the integration time or accumulation time. This is usually in the order of milliseconds (ms) but may extend to several hours in cooled type image sensors. In image sensors with a shutter function, the integration time can be set to the order of microseconds (us).

Interelectrode resistance (Rie) - PSD

This is the resistance between the opposing electrodes of a PSD when it is in a dark state. The interelectrode resistance is an important factor that determines the response speed, position resolution, and saturation photocurrent. The interelectrode resistance is measured with 0.1 V applied across the output terminals of the opposing electrodes while the common electrode is left open. When measuring the interelectrode resistance of a two-dimensional PSD, the output terminals other than the output terminals of the opposing electrodes are also left open.

Ionization rate

In an APD or other similar devices, electron-hole pairs are generated when the accelerated electrons and holes collide with the lattice while moving. The ionization rate is the number of these generated electron-hole pairs per unit distance. Units are in “per centimeter.”