RHF1401_12 STMICROELECTRONICS [STMicroelectronics], RHF1401_12 Datasheet - Page 28

• Manufacturer Part Number: RHF1401_12
• Description: Rad-hard 14-bit 30 Msps A/D converter
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

User manual
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Figure 53. 2 V
Figure 54
primary, while the secondary drives both ADC inputs. The transformer must be matched
with generator output impedance: 50
generator. The tracks between the secondary and VIN and VINB pins must be as short as
possible.
Figure 54. Differential implementation using a balun
The input common-mode voltage of the ADC (INCM) is connected to the center tap of the
transformer’s secondary in order to bias the input signal around the common voltage (see
Table 7: Internal reference
this node. Ceramic technology for decoupling provides good capacitor stability across a
wide bandwidth.
Analog input signal
(50 Ω output)
shows a differential input solution. The input signal is fed to the transformer’s
50 Ω track
pp
differential input
VIN -VINB (2 Vp-p)
ADT1 -1
1:1
INCM
voltage).The INCM is decoupled to maintain a low noise level on
Doc ID 13317 Rev 8
470 nF* ceramic
(as close as possible
to the transformer)
*the use of a ceramic technology is
preferable for a large bandwidth
stability of the capacitor
INCM
33 pF
Short track
in this case for proper matching with a 50
50 Ω
VIN
VINB
VINB
VIN
INCM
0.5V
REFP
1 V
REFMODE
INCM
REFM
100 nF* ceramic
(as close as
possible to
INCM pin)
Ground
AM04570
2.5V
RHF1401
External
INCM
(optional)
AM04571