Texas Instruments ADS5474, Руководство пользователя

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1 Overview
1.1 Purpose
1.2 EVM Basic Functions
1.3 Power Requirements
1.4 ADS-ADX EVM Operational Procedure
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Overview
This user’s guide gives a general overview of the ADS-ADX Evaluation Board for interleaving (later called
ADS-ADX EVM). It provides a description of the features and functions to consider when using the
module.
The ADS-ADX EVM provides a platform for evaluating two interleaved ADS5474 analog-to-digital
converters (ADC) with a combined sampling rate of 800 MSPS. The ADS5474 is a 14-bit, 400-MSPS ADC
which is pinout compatible with the ADS5463, a 12-bit, 500-MSPS ADC. For a more in-depth theoretical
description of ADC interleaving, consult the white paper
Frequency-Response Mismatch Errors and Digital
Correction in Time-Interleaved ADCs – available at www.spdevices.com . For system design with this
technology, consult the SP Devices application note Recommended Analog Front-End Design for ADX
with ADS5474/ADS5463 . The ADS-ADX EVM contains an ADC interleaving IP core from SP Devices. For
commercial information and available platforms, contact SP Devices.
One analog input into the EVM is provided via the SMA connector. The input is AC-coupled, and the user
supplies a single-ended input signal, which is converted into a differential signal at the input. The
ADS-ADX EVM provides an SMA connector for input of the ADC clock. The external clocking interface is
to be clocked with a 50% duty cycle clock, at half of the sampling rate of the interleaved system sampling
rate.
The interleaving and digital post-correction (ADX IP-core) is implemented in real time using the Virtex-5
FPGA on the board.
Digital output from the EVM is provided both by two Soft Touch Probe (support for Agilent E5405A and
Tektronix P6908 probes) connectors for logic analyzers and by a USB connector for connecting a
personal computer. The USB interface samples the data into internal FPGA memory, which has a
maximum depth of 65,536 samples.
The ADS-ADX EVM is powered through the 6-Vdc power supply adapter that is supplied. Power
consumption during operation is approximately 12 W for the board.
1. Verify the DIP switch settings to reflect your intended setup ( Section 2.5 and Table 2 )
2. Connect the supply power to the EVM, from the supplied mains adapter.
3. Press the reset button.
4. Use a 50-
Ω
function generator with an output swing of
±
1 V at the clocking speed of half the full
system, with a duty cycle of 50% (
±
3%).
5. Connect a 50-
Ω
function generator with a 55-MHz, 0-V offset, 700-mV amplitude sine wave to the input
of the ADC channel.
6. The digital output pattern on the Soft Touch Probe connector now represents a sine wave and can be
monitored with a logic analyzer.
7. Or connect a USB cable between the board and your computer, start the program ADCaptureLab
(installation: see section Software ), and collect the data. The plots provided are a time-series plot and
an FFT of the signal.
SLAU247 – August 2008 ADS5474 ADX Evaluation Board for Interleaving 3
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