THS770006_10 Datasheet, PDF (23/36 Pages) Texas Instruments – Broadband, Fully-Differential, 14-/16-Bit ADC DRIVER AMPLIFIER

THS770006
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APPLICATION INFORMATION
SBOS520 – JULY 2010
THS770006 DRIVING ADS5493
To illustrate the performance of the THS770006 as an ADC driver, the device is tested with the ADS5493. The
ADS5493 is a 16-bit, 130MSPS ADC with LVDS-compatible digital outputs on four data pairs. The device has an
analog input buffer to isolate the internal switching of the sampling stage from the inputs. Designed for high
SFDR, the ADC has low-noise performance and outstanding spurious-free dynamic range over a large
input-frequency range. Key information points to consider when interfacing to an amplifier are:
• Input buffer with constant load vs frequency
• 3.15V analog input common mode
• Full-scale differential input programmable from 1.5V_PP to 2.5V_PP
• 2kΩ differential input impedance with internal common-mode bias
• 4.6pF to 5.6pF for each analog input to ground (depending on PCB layout)
• SNR = 75.2dBFS (typ) at f_IN = 100MHz
• SFDR = 100dBc (typ) at f_IN = 100MHz
• HD₂ = 100dBc (typ) at f_IN = 100MHz
• HD₃ = 100dBc (typ) at f_IN = 100MHz
The ADS5493 EVM is designed for flexible options to ease design work. Used in conjunction with the
TSW1200EVM High Speed ADC LVDS Evaluation System, it reduces evaluation times to help the designer get
from prototype to production more quickly.
The ADS5493 EVM provides an input transformer for converting single-ended test signals to differential. The
differential outputs are configurable to drive the ADC directly through passive components or to insert the
THS770006 along with options for antialias filtering in the signal path to drive the ADC. The schematic of the
antialias filter components is shown in Figure 37. Note: the circuit shown is from an early prototype of the
ADS5493 EVM available at the time this data sheet was written and is provided as a reference only. The final
released board may have changes.
THS7700
Output
ADS5493
Input
Figure 37. ADS5493 EVM Antialias Filter Components
Copyright © 2010, Texas Instruments Incorporated
Product Folder Link(s): THS770006
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