The device requires two different power-supply voltages. 1.9-V DC is required for the VA19 power bus and 1.1-V DC is required for the VA11 and VD11 power buses. The power-supply voltages must be low noise and provide the needed current to achieve rated device performance. There are two recommended power supply architectures:

1. Step down using high-efficiency switching converters, followed by a second stage of regulation to provide switching noise reduction and improved voltage accuracy.
2. Directly step down the final ADC supply voltage using high-efficiency switching converters. This approach provides the best efficiency, but care must be taken for switching noise to be minimized to prevent degraded ADC performance. This approach is best described in the following application note: Powering Sensitive ADC Designs with the TPS62913 Low-Ripple and Low-Noise Buck Converter.

TI WEBENCH® Power Designer can be used to select and design the individual power supply elements needed: see the WEBENCH® Power Designer

• Decouple all power supply rails and bus voltages as they come onto the system board and near/at the ADC itself. Typically, one decoupling capacitor per power supply pin is sufficent unless specified in the datasheet or EVM assembly.
• Remember that approximately 20 dB/decade noise suppression is gained for each additional filtering stage.
• Decouple for both high and low frequencies, which might require multiple capacitor values.
• Series ferrite beads are commonly used at the power plain entry point. This should be done for each individual supply voltage on the system board whether it comes from an LDO or a switching regulator.
• For added capacitance, use tightly stacked power and ground plane pairs (≤4 mil spacing) this adds inherent high-frequency (>500MHz) decoupling to the PCB design.
• Keep supplies away from sensitive analog circuitry such as the front-end RF stage of the ADC and high-speed clocking & digital circuits if possible.
• Some switcher regulator circuitry/components could be located on the opposite side of the PCB for added isolation.
• Follow the IC manufacture recommendations; if they are not directly stated in the application note or data sheet, then study the evaluation board. These are great vehicles to learn from. Applying these points above can help provide a solid power supply design yielding datasheet performance in many applications.

Each application will have different tolerances for noise on the supply voltage so understanding these trades is best described in the following two application notes for more details:

1. Clutter-free power supplies for RF converters in radar applications (Part 1)
2. Clutter-free power supplies for RF converters in radar applications (Part 2)

Also refer to both Figure 7-5 and Figure 7-6 to illustrate a few different approaches.

FB = ferrite bead filter.

Figure 7-5 LDO Linear Regulator Approach Example

FB = ferrite bead filter.

Figure 7-6 Switcher-Only Approach Example