STAR1000  
					Addressing Logic  
					amplifier. As a result, the pixels are always reset immediately  
					after read out as part of the sample procedure. Note that the  
					maximum integration time of a pixel is the time between two  
					read cycles.  
					The addressing logic allows direct addressing of rows and  
					columns. Instead of the one-hot shift registers that are often  
					used, address decoders are implemented. One can select a  
					line by presenting the required address to the address input of  
					the device and latching it to the Y- decoder logic. Presenting  
					the X- address to the device address input and latching it to  
					the X- address decoder can select a column.  
					Output Amplifier and Analog Multiplexer  
					The output amplifier combines subtraction of pixel signal level  
					from reset level with a programmable gain amplifier. Since the  
					amplifier is AC coupled, it also contains a provision to maintain  
					and restore the proper DC level.  
					A typical line read out sequence will first select a line by  
					applying the Y-address to the Y-decoder. Activation of the  
					LD_Y input on the Y-logic connects the pixel outputs of the  
					selected line to the column amplifiers. The individual column  
					amplifier outputs are connected to the output amplifier by  
					applying the respective X- addresses to the X- address  
					decoder. Applying the appropriate Y- address to the Y-  
					decoder and activating the “Reset” input reset a line. The  
					integration time of a row is the time between the last reset of  
					this row and the time when it is selected for read out.  
					An analog signal multiplexing feeds the pixel signal to the final  
					unity gain buffer, providing the required drive capability. Apart  
					from the pixel signal, three other external analog signals can  
					be fed to the output buffer. All these signals can be digitalised  
					by the on-chip ADC if the output of this buffer is externally  
					connected to the input of the ADC.  
					The purpose of the additional analog inputs (A_IN1, A_IN2,  
					and A_IN3) is to allow the possibility of processing other  
					analog signals through the image sensors signal path. These  
					signals can then be converted by the ADC and processed by  
					the image controller FPGA. The additional analog inputs are  
					intended for low frequency or DC signals and have a reduced  
					bandwidth compared with the image signal path.  
					The Y- decoder logic has two different reset inputs: RESET  
					and RESET_DS. Activation of RESET resets the pixel to the  
					Vdd level; activation of RESET_DS resets the pixel to the  
					voltage level on the VREF input. This feature allows the appli-  
					cation of the so called dual slope integration. If dual slope  
					integration is not needed, VREF is tied to Vdd and RESET_DS  
					must never be activated.  
					ADC  
					The image sensor has a 10-bit ADC that is electrically  
					separated from the rest of the image sensor circuits and can  
					be powered down if an external ADC is used. The conversion  
					takes place at the falling edge of the clock and the output pins  
					can be disabled to allow operation of the device in a bus  
					structure.  
					Column Amplifiers  
					All outputs from the pixels in a column are connected in parallel  
					to a column amplifier. This amplifier samples the output  
					voltage and the reset level of the pixel whose row is selected  
					at that moment and presents these voltage levels to the output  
					Document Number: 38-05714 Rev. *B  
					Page 8 of 21  
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