Notes on different FPIX0 pixel unit cells

Click here for a "map" of FPIX0 unit cell differences

The nominal FPIX0 amplifier uses a 20 fF feedback capacitor; pixels in columns 1 and 9 are "high gain" cells. In these cells, the feedback capacitance is ~10 fF. The difference between the high gain cells and the standard cells is that the poly layer has been removed from the feedback capacitor in the high gain cells (making it a two plate cap, rather than a three plate cap).

In column 5, cells 0-7 have intermediate gain. In these cells, poly is removed from all three capacitors (the first stage feedback cap, the coupling cap, and the second stage feedback cap). The gain of these cells is not quite as high as the high gain cells, because the coupling cap is smaller than the second stage feedback cap, so removing poly from these two caps results in a different ratio than the standard cell. These cells were modified to explore the possibility the standard cell might suffer from noise or crosstalk related to coupling between poly and the substrate.

No charge injection is possible for cells 0-7 of column 4.

Cells 0-15 of column 2 have no peak detector (Can not use analog output).

The charge injection network for columns 6 and 7 uses one switch where a complementary pair is used in all other columns. Cells in these two columns will always see the charge injection pulse if this pulse is negative voltage. (All voltages presented to the FPIX0 should be between the voltage rails.)


Last Updated on 5/12/99
By David Christian