PI6049A Data Sheet

__________________________________________________________________________________________

PI6049A Unique Features

There are five unique features incorporated in the PI6049A which improve the sensor’s performance.

1. Pixel-to-Pixel Offset Cancellation Circuit

The sensor employs a pixel-to-pixel offset cancellation circuit, which reduces the Fix Pattern Noise (FPN), and

amplifier offsets. In addition, this innovative circuit design greatly improves the optical linearity and low noise

sensitivity.

2. Parallel Integrate, Transfer and Hold

The sensor has a parallel integrate, transfer and hold feature, which allows the sensor to be read out while photon

integration is taking place. These features are approached through the use of an integrate and hold cell, located

at each pixel site. Each pixel’s charge is read from its storage site as the sensor’s shift register sequentially

transfers each pixel’s charge onto a common video line.

3. Dual Scan Initiation Inputs, GBST and SI

Each sensor has two scan initiation inputs, the Global Start Pulse (GBST) and the Start Pulse (SI). These clocks

help to reduce the sensor-to-sensor transition Fix Pattern Noise by initializing and preprocessing all sensors

simultaneously before they start their readout scan. The internal shift register starts the scan after GBST is

clocked in on the falling edge of the Clock input (CLK).

The Start Input Control (SIC) selects the first sensor in a sequence of cascaded sensors to operate with 29 clock

cycles of delay by connecting it to Vdd on the first sensor, and to Ground for all subsequent sensors. Then, only

the first sensor clocks out 29 inactive pixels before accessing its first active pixel. During these 29 clock cycles,

the first sensor and all of the subsequent cascaded sensors cycle through their pre-scan initialization process.

After initialization, only the first sensor starts its read cycle with its first-active pixel appearing on the 30

cycle. The second and subsequent sensors await the entry of their Start Pulse (SI). Furthermore, the first sensor’s

Start Pulse (SI) is left unconnected, while the subsequent sensors all have their Start Pulse’s (SI) connected to

the SO of their respective preceding sensor. The external scan Start Pulse (SI) is connected to all of the sensors'

Global Start Pulse (GBST) inputs.

As the first sensor completes its scan, its End-of-Scan (SO), appears 1 pixel before its last pixel. The second and

subsequent sensors will then start their registers 1 clock cycle before the appearance of their respective first

pixels, and their SO also appears 1 pixel before their last pixel.

4. Power Saving

Each sensor incorporates a power-saving feature when multiple sensors are cascaded together to form a linear

imaging array. The Start Input Control (SIC) on each sensor selects a unique feature of powering up a particular

sensor’s output amplifier when it’s selected and powering it down when not selected. For the PI6049A, only the

first sensors’ amplifier is used and all subsequent sensors have their amplifiers turned off. The pixels from each

sensor are transferred onto a common video line which is connected to the amplifier of the first sensor. The

advantage of using only one active amplifier is two fold; saving on power consumption and reducing sensor-to-

sensor FPN.

5. Common Reference Voltage between Cascaded Sensors

Each sensor has an input/output bias control (VR), which serves as an offset voltage reference. Each bias control

pad is connected to an internal bias source and tied to its own amplifier’s reference bias input. In operation, these

pads on every sensor are connected together. Each sensor then “shares” the same bias level to maintain a

constant bias among all of the sensors.

Page 3 of 13, Revised 2-13-04