ISL59533 Datasheet, PDF (22/24 Pages) Intersil Corporation – 32x32 Video Crosspoint with Differential Inputs

ISL59533
demoboard without the socket. The parasitic capacitance of
the demoboard is about 2.7pF less.
FIGURE 48. ENGINEERING EVALUATION BOARD
0.0
-1.2
Demo
Eng Eval
-2.4
-3.6
-4.8
-6.0
1
10
100
Frequency [MHz]
FIGURE 50. FREQUENCY RESPONSE - ENG EVAL BOARD vs
DEMO
Linear Operating Region
In addition to bandwidth, one must also be very careful with
operating the device at its linear operating region. Figure 51
shows differential gain curve. The ISL59533 is a single
supply 5V device with its linear region is between 0.1 and
2V. The signal range is fine for most video signals whose
nominal signal amplitude is 1V. Both inputs should be
maintained at 0.3V or above for best operation. A DC restore
circuit is required to put the video signal within the linear
operating region of the crosspoint switch.
FIGURE 49. CUSTOMER DEMOBOARD
To prove that the parasitic capacitance is the largest
contributor to the difference in bandwidth of the two boards,
we added 2.7pF at the output of the demoboard. Figure 50
shows the similarity in frequency response of the
engineering evaluation board alongside the demoboard
piggybacked with 2.7pF.
FIGURE 51. DIFFERENTIAL GAIN RESPONSE
22
FN6222.0
March 13, 2006