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SBAS308A− MAY 2004 − REVISED MARCH 2005
Another possible configuration for lower-frequency sig-
nals is the use of differential input/output amplifiers that
can simplify the driver circuit for applications requiring
DC coupling of the input. Flexible in their configurations
(see Figure 40), such amplifiers can be used for single-
ended-to-differential conversion, signal amplification.
Table 4. Recommended Amplifiers to Drive the Input of the ADS5542
INPUT SIGNAL FREQUENCY
RECOMMENDED AMPLIFIER
THS4503
TYPE OF AMPLIFIER
Differential In/Out Amp
USE WITH TRANSFORMER?
DC to 20MHz
DC to 50MHz
No
Yes
Yes
Yes
Yes
Yes
OPA847
OPA695
THS3201
THS3202
THS9001
Operational Amp
Operational Amp
Operational Amp
Operational Amp
RF Gain Block
10MHz to 120MHz
Over 100MHz
−
+5V 5V
RS
RIN
RIN
Ω
100
µ
0.1 F
25Ω
25Ω
VIN
1:1
INP
INM
OPA695
RT
100
CIN
ADS5542
1000pF
Ω
R1
Ω
400
CM
10
AV = 8V/V
(18dB)
R2
57.5
Ω
Ω
µ
0.1 F
Figure 39. Converting a Single-Ended Input Signal to a Differential Signal Using an RF Transformer
22
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