ADS62P49 Datasheet, PDF (55/76 Pages) Texas Instruments – Dual Channel 14-/12-Bit, 250-/210-MSPS ADC With DDR LVDS and Parallel CMOS Outputs

ADS62P49 / ADS62P29
ADS62P48 / ADS62P28
www.ti.com............................................................................................................................................................. SLAS635A – APRIL 2009 – REVISED JUNE 2009
0.1 mF
1:1
0.1 mF
39 nH
50 W
25 W
0.1 mF
50 W
1:1
0.1 mF
39 nH
25 W
15 W
50 W
22 pF
50 W
15 W
INP
INM
VCM
Figure 96. Drive Circuit With Low Bandwidth (for low input frequencies)
S0396-01
0.1 mF
1:1
0.1 mF
5W
25 W
0.1 mF
1:1
0.1 mF
25 W
5W
50 W
3.3 pF
50 W
INP
INM
VCM
Figure 97. Drive Circuit With High Bandwidth (for high input frequencies)
S0397-01
0.1mF
INP
0.1mF
25 W
T1
T2
0.1mF
25 W
INM
VCM
Figure 98. Drive Circuit with Very High Bandwidth (> 300 MHz)
All these examples show 1:1 transformers being used with a 50-Ω source. As explained in the “Drive Circuit
Requirements”, this helps to present a low source impedance to absorb the sampling glitches. With a 1:4
transformer, the source impedance will be 200 ohms. The higher impedance can lead to degradation in
performance, compared to the case with 1:1 transformers.
Copyright © 2009, Texas Instruments Incorporated
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