STAR1000
Document Number: 38-05714 Rev. *B
Page 7 of 21
Architecture
Floor Plan
Figure 3. Star1000 Floor Plan
The image sensor contains five sections: the pixel array, the
X- and Y- addressing logic, the column amplifiers, the output
amplifier and the ADC. Figure 3. shows an outline diagram of
the sensor, including an indication of the main control signals.
The following paragraphs explain in more detail the function
and operation of the different imager parts.
Pixel Array
The pixel array contains 1024 by 1024 active pixels at 15
µm
pitch. Each pixel contains one photo diode and three
transistors (Figure 4.).
The photo diode is always in reverse bias. At the beginning of
the integration cycle, a pulse is applied to the reset line (gate
of T1) bringing the cathode of D1 to the reset voltage level.
During the integration period, photon-generated electrons
accumulate on the diode capacitance reducing the voltage on
the gate of T2. The real illumination dependent signal is the
difference between the reset level and the output level after
integration. This difference is created in the column amplifiers.
T2 acts as a source follower and T3 allows connection of the
pixel signal (reset level and output level) to the vertical output
bus.
The reset lines and the read lines of the pixels in a row are
connected together to the Y- decoder logic; the outputs of the
pixels in a column are connected together to a column
amplifier.
Figure 4. Architecture of the 3T Pixel
Reset
Reset_DS
Vref
Ld_Y
A0....A9
Y Address
Decoder
and Logic
Pixel Array
1024 x 1024 pixels
1024
Rst
1024
Rd
10
Rst
Rd
Col
10-bit ADC
10
D0...D9
Clk_ADC
Ain
S
R
Column Amplifiers
1024
1024
1024
10
10
1024
1024
Clk_X
Ld_X
X Register
X Address Decoder
Rst
Sig
Progr. Gain
Amplifier
Buffer
Aout
T1
T2
T3
Read
Reset
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