AMIS-720341

AMIS-720341-A: Contact Image Sensor Data Sheet 1.0 Description AMI Semiconductor’s AMIS-720341-A (PI3041A) contact image sensor (CIS) chip is a 300 dots per inch (dpi) resolution, linear array image sensor chip. The sensor chip is processed using a CMOS image sensing technology and it belongs to the Image Sensor Product Line (ISPL) group within AMIS. Designed for cascading multiple chips in a series, the image sensor chips use a chip-on-board process. They are bonded end-to-end on a printed circuit board (PCB). This bonding process allows the CIS module manufacturers to produce variable CIS module lengths in increments of the chip array lengths. Hence, the modules are easily applied in a large number of document scanners found in today’s facsimile market. Some examples of these large document scanners are those that produce wide format maps and architectural drawings, down to the narrow width scanners, such as those found in check readers, lotto tickets, entrance gates tickets, etc. This is not to exclude office automation equipment, which requires an even more variety in scanning widths, as well as those with special mechanically configurations. Figure 1 is a block diagram of the imaging sensor chip. Each sensor chip consists of 96 detector elements, their associated multiplexing switches, buffers, and a chip selector. The detector's element-to-element spacing is approximately 83.3µm. The size of each chip without scribe lines is 8080µm by 380µm. Each sensor chip has seven bonding pads. The pad symbols and functions are described in Table 1. 8080 mm Row of 96 Sensors and Video Signal Multiplexers Readout Shift Register 380 mm Buffer SP Buffer CP VDD DGND Chip Select IOUT Buffer AGND EOS Figure 1: AMIS-720341-A Block Diagram Table 1: Pad Symbols and Functions Symbol Function SP Start pulse: input clock to start the line scan CP Clock pulse: input clock to clock of the shift register VDD Positive supply: +5V supply connected to substrate DGND Digital ground: connection topside common IOUT Signal current output: output for video signal current AGND Analog ground: connection topside common EOS End-of-scan pulse: output from the shift register at end-of-scan AMI Semiconductor – May 06, M-20570-001 www.amis.com 1 AMIS-720341-A: Contact Image Sensor 2.0 Bonding Pad Outputs Locations and Die Dimensions Data Sheet Figure 2 shows the die dimensions of the image sensor and the bonding pad locations for the AMIS-720341-A sensor chip. The location is referenced to the lower left corner of the die. Figure 2: Bonding Pad and Chip Layout AMI Semiconductor – May 06, M-20570-001 www.amis.com 2 AMIS-720341-A: Contact Image Sensor 3.0 Wafer Scribe Lines Bordering the Die Figure 3 shows the wafer scribe lines bordering the AMIS-720341-A sensor chip. The wafer thickness is 350µm. Data Sheet Figure 3: Wafer Scribe Lines AMI Semiconductor – May 06, M-20570-001 www.amis.com 3 AMIS-720341-A: Contact Image Sensor 4.0 Output Circuit of the Image Sensor Data Sheet The video signal from each photo-site is connected to a common video line on the sensor. Each photo-site is composed of a phototransistor with a series MOS switch connecting its emitter to a common video line. The video line is connected to the pad labeled IOUT. The photo-sites are read out upon the closure of the MOS switch, which is sequentially switched on and off by its internal scanning shift register (see Figure 1). For the clock and timing operation image sensor see Figure 11. The photo-sensing element is the base of the phototransistor where it detects and converts the light energy to proportional charges and stores them in its base and collector capacitance. When the MOS switch is activated, the emitter is connected to the video line and acts as the source follower, producing an impulse current proportional to the stored charges in the base. This current is a discrete-time analog signal output called the video pixel. The charges in the video pixel are proportional to the light energy impinging in the neighborhood of its photo-sites. Figure 4 shows an output structure of four photo-sites out of 128. The multiplexing MOS switch in each photo-site terminates into the output pad, IOUT, through a common video line. As the shift register sequentially accesses each photo-site, the charges of the video pixel is sent to the IOUT where they are processed with an external signal conversion circuit. See Section 5.0. Figure 4: Video Pixel Output Structures AMI Semiconductor – May 06, M-20570-001 www.amis.com 4 AMIS-720341-A: Contact Image Sensor 5.0 Signal Conversion Circuit Data Sheet Figure 5 is an example of the charge conversion that is used in the CIS modules. It is usually bonded on the same PCB on which the image sensors are bonded. In applications where cost is an important factor, this simple circuit provides the cleanest technique in processing the video output. It integrates all the currents from each pixel element onto a capacitor (CAP). It also sums the energy of the switch edge along with the signal current pulses, minimizing the switching patterns on the video pixels. The summed charges stored on the CAP produce a pixel voltage. This voltage amplitude is proportional to the charge from the current pulse and the value of the CAP. Figure 5: Video Output Test and Application Circuit Since switching energies are components with high frequencies, they tend to integrate to a 0 value and the remainder adds a constant value to offset the dark level. After the pixel is integrated, the CAP is reset to 0V by activating the shunt switch, SW, that connects the video line to ground prior to accessing the following pixel element. Figure 6, which depicts a typical pixel voltage waveform, shows that the shunt time is controlled with CP. SW activation and the reset to the dark reference level of the pixel element storage occur simultaneously, initializing the pixel for its integration process cycle. The signal pixels Vp(n) is referenced to its dark level as seen in Figure 6. Figure 6: Single Pixel Video Output AMI Semiconductor – May 06, M-20570-001 www.amis.com 5 AMIS-720341-A: Contact Image Sensor 6.0 Two Test Setups for Specifications and Performance 6.1 First Setup Data Sheet The standard specifications are the image sensor tests that are performed on the wafer probe machine, where each device on the wafer is tested in production. However, the data in these measurements are measured with a clock frequency at a fixed 500kHz. Since the pixel rate is equal to the clock rate, the pixel rate is also at 500kHz. The specification under Section 7.0 is the wafer probe specifications, Table 2. 6.2 Second Setup The CIS modules made with these devices operate in excess of 5.0MHz. Accordingly, the wafer probe specifications are supplemented with high frequency clocking performance using an A6 length module’s PCB board. 7.0 Electro-Optical Characteristics (25°C) The electro-optical characteristics of the AMIS-720341-A imaging sensor chip are listed in Table 2. This is the wafer probe specification ° used to test each die at 25 C. Table 2: Electro-Optical Characteristics Parameters Number of photo-elements Pixel-to-pixel spacing Line scanning rate Clock frequency Output voltage Output voltage non-uniformity Dark output voltage Dark output non-uniformity Adjacent pixel non-uniformity Chip-to-chip non-uniformity Notes: (1) Symbols Tint (2) Fclk (1) Typical 128 ~83.3 128/Fclk 500 1.85 ± 0.35 ± 7.5