TLV9001-Q1: Why CMRR and PSRR decrease with the increasing of frequency?

Leo Ma

Expert 4196 points

Part Number: TLV9001-Q1

Hi Expert,

Have a nice day! I have questions about TLV9001-Q1’s PSRR and CMRR:

Why these two features decrease with the increasing of frequency?

Best Wishes,

Leo

6 months ago

0 Ron Michallick 6 months ago

TI__Guru**** 172566 points

Hello Leo,

PSRR and CMRR drop in frequency because the op amp open loop gain also drops with higher frequency.

Also 7-15 doesn't look right. CMRR vs frequency test requires (near) perfect external components and should compensate for actual forward gain. Neither was done fully.

This is a more realistic CMRR curve. However the knee would be curved.

0 Leo Ma 6 months ago in reply to Ron Michallick

TI__Expert 4196 points

Hi Ron,

Thanks for reply.

Where does this picture from? Which device? And what the black and green curve mean?

Best Wishes,

Leo

0 Ron Michallick 6 months ago in reply to Leo Ma

TI__Guru**** 172566 points

Leo,

The picture came from your first post.

I made the green curve from the 95dB value in the TLV9001-Q1 data sheet.

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TLV9001-Q1: Why CMRR and PSRR decrease with the increasing of frequency?