RHF1201_11 STMICROELECTRONICS [STMicroelectronics], RHF1201_11 Datasheet - Page 22

• Manufacturer Part Number: RHF1201_11
• Description: Rad-hard 12-bit 50 Msps A/D converter
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Electrical characteristics (unchanged after 300 kRad)
22/34
The RHF1201 is designed for use in a differential input configuration. Nevertheless, it can
achieve good performance in a single-ended input configuration. In single-ended, a good-
quality conversion can be achieved by using an input amplitude up to 1.4 Vp-p with external
references INCM and VREFP (see
Figure 49. 2 V
The RHF1201 is designed to obtain optimum performance when driven on differential inputs
with a differential amplitude of 2 V peak-to-peak (2 V
VIN and VINB inputs in phase opposition.
The RHF1201 is specifically designed to meet sampling requirements for IF, intermediate
frequency input signals. In particular, the track-and-hold in the first stage of the pipeline is
designed to minimize the linearity limitations as the analog frequency increases. This is
achieved by making the input impedance independent of the input frequency.
Figure 50 on page 23
transformer’s primary, while the secondary drives both ADC inputs. The transformer must be
50 Ω matched (for proper matching with a 50 Ω generator), and it must be loaded with 50 Ω
on the secondary, as close as the ADC. Tracks between the secondary and VIN and VINB
pins must be as short as possible.
The 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 this common voltage,
internally set to 0.52 V (see
noise level on this node. Ceramic technology for decoupling provides good capacitor
stability across a wide bandwidth.
p-p
differential input
VIN -VINB (2 Vp-p)
shows a differential input solution. The input signal is fed to the
Table 7 on page
Doc ID 12585 Rev 5
Figure 38 on page
INCM
10).The INCM is decoupled to maintain a low
VIN
VINB
p-p
17).
). This is the result of 1 V
or external)
(Internal
INCM
REFP
1 V
REFM
Ground
AM04544
p-p
RHF1201
on the