PGA460-Q1: Low-Noise Ampfiler and PGA Ampfiler in PGA460-Q1

Prodigy 220 points

Part Number: PGA460-Q1
Other Parts Discussed in Thread: PGA460

Hi team,

I'm designing the ultrasonic sensing schematics that incorporates PGA460-Q1,

and I have a question about Figure.5 in PGA460-Q1 datasheet p15 .

Are Low-Noise Ampfiler and PGA Ampfiler physically separated?

Or is it expressed as a model and is it one amplifier in reality?

(I am worried about 2-layer amplifiers circuit will be noisy and it cannot be amplified with high precision.)

Thanks.

over 4 years ago

0 Isaac Lara over 4 years ago

TI__Mastermind 23045 points

Hello tr,

The Low-Noise Amplifier (LNA ) and Programmable Gain Amplifier (PGA) are two separate gain stages within the PGA460-Q1. The LNA contains a fixed gain value and the PGA stage implements a time-varying amplifier which can be used to amplify the signal at the listening phase in order to reduce excess noise. Additionally, the following stage is a bandpass filter that is used to reduce noise created by the LNA, PGA, and external noise.

This video contains some more information about the receiver stages found in the PGA460: https://training.ti.com/ti-precision-labs-ultrasonic-sensing-ultrasonic-receiver?context=1139747-1139746-1147829-1147769

Regards,

Isaac

0 tr over 4 years ago in reply to Isaac Lara

Prodigy 220 points

Thank you, Isaac.

I 've understood LNA and PGA are physically separated and 2-stage Amplifiers don't become a problem.

Could you tell me the fixed gain value of LNA?

I would like to estimate enough voltage amplitude for PGA460-Q1 to detect a peak in Echo Data.

Regards,

0 Isaac Lara over 4 years ago in reply to tr

TI__Mastermind 23045 points

Hey tr,

Even though they are two separate stages the data sheet lists the gain for both stages together as a range anywhere between 32dB to 90dB. My suspicion is that the LNA has a fixed gain of 32dB and the PGA just adds to that as needed for your application up to the maximum of 90dB.

Best,

Isaac

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PGA460-Q1: Low-Noise Ampfiler and PGA Ampfiler in PGA460-Q1