EVM430-FR6043: phase shift introduced by amplifer

user4843074

Part Number: EVM430-FR6043
Other Parts Discussed in Thread: OPA838, OPA836

How to calculate the final dTOF and convert it to flow rate when considering the phase shift introduced by amplifer?

Refer to sboa309.pdf,

opa838 or opa836 is chosen for the reason a much higher GBW than the signal frequency minimizes the phase shift introduced.

Then the output is sent to the internal PGA of MSP430FR604x. Will the phase shift change when setting different gains of the PGA?sboa309.pdf

over 7 years ago

0 Eddie LaCost over 7 years ago

TI__Mastermind 47535 points

Hello,

I will need to research this and provide you with feedback shortly. Thanks!

0 Eddie LaCost over 7 years ago in reply to Eddie LaCost

TI__Mastermind 47535 points

Yes, the phase shift could be different for different gain settings of the PGA as there is some frequency response, but the DToF will encounter the same phase shift on both the UPS and DNS signal which should get cancelled away when the differential ToF is estimated.

0 user4843074 over 7 years ago in reply to Eddie LaCost

Prodigy 25 points

Refer to tiduej6.pdf

Equation 4

The velocity of gas medium is directly proportional to (1/Tup - 1/Tdown) = △T/(Tup*Tdown)

Does it mean the delay is cancelled on numerator but gets error on the denominator?

0 Eddie LaCost over 7 years ago in reply to user4843074

TI__Mastermind 47535 points

Sorry for the delay in my response.

In theory, you are correct that there will be some error, but because the OPA836 or OPA838 is a high GBW device, the error introduced is negligible compared to any other error seen in the system.

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EVM430-FR6043: phase shift introduced by amplifer