PGA280: PGA280 for CCD AFE

Noniel Paul Novabos

Part Number: PGA280
Other Parts Discussed in Thread: PGA870

Hi,

I am new to analog circuit design and I need to design the analog front end for a CCD imaging system (Pushbroom camera). I am using the TCD2905 RGB linear CCD and the LTC2246 ADC. I need help in integrating the PGA280 in my system (design considerations and best practices). It is the best fit for my application as I need to digitally control the gain and set the output's common-mode voltage according to the ADC's requirements. The CCD operates at a maximum frequency of 20MHz but I am only planning on operating at 4MHz. Any help is greatly appreciated.I have attached the datasheets of the CCD sensor and the ADC.

Best Regards,

PaulLTC2246_Datasheet.pdf TCD2905CF.pdf

over 3 years ago

0 Luis Chioye over 3 years ago

TI__Mastermind 49405 points

HI Paul,

The PGA280 is a relatively low bandwidth instrumentation amplifier primarily optimized for DC precision applications or relatively low bandwidth signals. The small signal bandwidth of the PGA280 is a function of gain, as shown on Figure 17 of the datasheet. The frequency response is optimal (in the flat region) for input frequencies below <~20kHz. If you are interested in sampling input signals in the ~Megahertz frequency range this would be well outside the frequency response of the PGA280.

The LTC2246 is a also a high speed pipeline ADC (14-Bit, 25Msps); the PGA280 is not fast enough to drive this ADC.

These types of pipeline ADCs are typically interfaced with high speed, high bandwidth differential amplifier drivers.

Thank you and Regards,

Luis

0 Noniel Paul Novabos over 3 years ago in reply to Luis Chioye

Prodigy 200 points

Hi Luis,

Thank you for the response. Is there a high speed driver that you can recommend?
I was browsing the TI PGA parts and found the PGA870. Would this be a good replacement?

Thanks and Regards,

Paul

0 Luis Chioye over 3 years ago in reply to Noniel Paul Novabos

TI__Mastermind 49405 points

Hi Paul,

Yes, the PGA870 (650-MHz) is a high-speed, fully differential programmable gain amplifier which is probably a much better fit to drive a high-speed pipeline ADC. The PGA870 is supported by a different team, and I will need to refer your question to the proper applications team.

Thank you and Kind Regards,

Luis

0 Noniel Paul Novabos over 3 years ago in reply to Noniel Paul Novabos

Prodigy 200 points

Hi Luis,

Also, note that my design is still not final so if you already have a reference design for a PGA and ADC operating at the same frequency I stated that would be very helpful.

Thanks,

Paul

0 Luis Chioye over 3 years ago in reply to Noniel Paul Novabos

TI__Mastermind 49405 points

Hi Paul,

There are a couple integrated devices analog front ends incorporating PGAs and high speed ADCs for CCD applications that could be of interest.

If you have further questions about these devices or other CCD imaging reference designs, kindly start a new thread with with the specific topic so you may get to the correct applications support team, since this system is not related to the PGA280 instrumentation amplifier.

Thank you and Regards,

Luis

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