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THS4302EVM: amplifier bandwidth

Ernest Yong
Expert 4315 points
Part Number: THS4302EVM
Other Parts Discussed in Thread: THS4302, OPA855

Hi Team,

Customer have a question regarding the THS4302 fixed gain amplifier -- They're planning to use this part in an analogue frontend design with a small-signal bandwidth in excess of 2 GHz. Their design doesn't meet this bandwidth target, and they've traced the bottleneck back to the THS4302 amplifier. 

The THS4302 datasheet claims a small signal bandwidth of about 2.5 GHz (with an output of 200 mV into 100 Ohms);

They've tested the THS4302 evaluation module on a VNA with sweep amplitude of -24 dBm (which yields 200 mVpp at the amplifier output). A Bode plot of the measured frequency response is shown below;

As you can see, the - 3dB breakpoint is quite a bit below the 2.5 GHz shown in the datasheet, for the same amplitude, output termination and power supply conditions.

Any insight you could provide would be appreciated (or recommendations of alternative parts that can meet the spec),

Best Regards,

Ernest

  • 0
    TI__Expert 8650 points

    Hi Ernest,

    Thank you for the information you provided. There is variation in device performance where specs like GBW vary due to process variation. I will try recreating this result on our end just to see if there might be something that can be adjusted in your configuration. Please allow some time to get this complete on our end as we are ordering a new EVM to test this spec. However, if the customer is considering an alternative, we do have the OPA855. This is a decompensated device which means it requires a minimum gain, in this case 7V/V. The device has a typical small-signal bandwidth of 2.5MHz at this gain. The datasheet for this device can be found here. This device also has an EVM if the customer would like to test the device.

    Best Regards,

    Ignacio