Transient Response of LDO for Load switching at GHz

Hi all,

I have a HDMI Rx which switches at few Giga bits per second. I am using an LDO to Power the HDMI Rx IC.
So how should i choose the LDO based on transient response. I know how to choose LDO based on Input voltage, output voltage and current drawn. But i am not sure how to choose based on transient response.
Should the LDO have transient response as that of load (which i assume, is usually not possible)?
Between two LDO's choosing a better one is easy job, but how to choose an LDO based on Load conditions. My load draws 200mA of current from 1.8V rail.

Regards
Vinod A H

The voltage regulator transient response will for sure be irrelevant for frequencies above 1 MHz.

The high frequency regulation is entirely done by capacitors on the PCB, power plane capacitance, and on-chip decoupling. The PCB will have a mix of large capacitances (low frequencies), and low capacitances (0.1uF for higher frequencies) placed near the chip. Power planes are also essential at that high frequency.

You should really check out some references on doing high-speed design because there's a lot of issues that you will need to consider. What you are asking about is power integrity, but you'll also need to consider signal integrity if you were laying out the board. I'd recommend this book which covers both in an introductory manner:

Amazon.com: Signal and Power Integrity - Simplified (2nd Edition) (9780132349796): Eric Bogatin: Books

You need enough low-ESR, low-ESL bypass capacitance
to give you the voltage ripple you can tolerate, from the
charge spikes you will generate, with the assumption that
the LDO is nothing but a current source in-the-moment.