ONET4291TA: AGC response time

May

Part Number: ONET4291TA

Hi,

Customer is looking for the following information, please see details below.

" I need to know the response time of the automatic gain control for this chip. For example, recovery time after saturation, gain establishment time after power on, in general the averaging time to determine the AGC level. "

Thank you in advance.

Regards,
Maynard

over 3 years ago

0 Sima Jalaleddine over 3 years ago

TI__Mastermind 31205 points

Hello Maynard,

AGC circuitry monitors the voltage drop across the internal 220Ω filter resistor to set the AGC. Then, the MOSFET acts as a controlled shunt and lowers the transimpedance feedback resistor.

Unfortunately, it doesn't seem like we have information on the response time of the AGC due to this device not considered as a burst-mode TIA. More details can be found on this older thread. But, I will ask the design engineers for more information, and will update you shortly.

Thank you,
Sima

0 May over 3 years ago in reply to Sima Jalaleddine

TI__Genius 9880 points

Hi Sima,

Thank you and looking forward to your update.

Also, customer want to know, how long after power on would a signal be transmitted by the chip? Would it be faster if AGC were turned off?

Regards,
Maynard

0 May over 3 years ago in reply to May

TI__Genius 9880 points

Hi Sima,

I just want follow up on this, any update what we can provide to the customer?

Thank you.

Regards,
Maynard

0 Sima Jalaleddine over 3 years ago in reply to May

TI__Mastermind 31205 points

Hello Maynard,

Sorry for the delay on this issue. We are currently looking into the RSSI/AGC block vs FET as the bottleneck for response time. Not too sure if we will be able to provide a quantifiable/numerical answer, but should be able to give more details then known above. I will update you by end of the week at the latest.

Thank you,
Sima

0 Sima Jalaleddine over 3 years ago in reply to Sima Jalaleddine

TI__Mastermind 31205 points

Hello Maynard,

I received confirmation from the design engineer:

RSSI bandwidth specified at 3.5MHz is considered the same as the AGC block. We don’t have sufficient data on how fast the TIA comes out of clamping, and the response time is slower than usually required for a burst mode application.

Thank you,
Sima

Interface

Interface forum

ONET4291TA: AGC response time