VGA DC - Frequency

Hello all,

I'm a student Electronics and still new to Texas Instruments. I've been trying to find a suitable VGA for what i need, but I can't seem to find it. I do not have much expertise working with amplifiers yet, so it might be that I am missing some basic knowledge of what is available and what is possible. I'm making a receiver that receives signals of 150MHz, it has been through 2 mixers and brought down to near DC and now requires the gain to be variable. This is due to the fact that the transmitter has parts that are unknown (and stay unknown).

I'm looking for a Variable Gain Amplifier (or PGA maybe) that is single in/single out and works for a frequency of around 10k-100kHz. It should have a total gain range of at least 30 dB or more, (this might be 0-30, or -15 to 15) Unfortunately when I look at the search list for VGA, it doesnt show an option for min/max frequencies. Most chips I find have a minimum frequency well above what I need or are differential inputs/outputs.  

I do not know how to change a differential to a single input or output (connecting 1 of them to ground works?). 

I hope someone might help me or shed some light on what i should be looking for. If any more information is required, i'll happily provide it.

With kind regards,

Floris

1 Reply

  • Hello Floris,

    It sounds from your description that a linear voltage-controlled amplifier (VCA) may be an appropriate solution. The one device that comes to mind is the VCA810. You can find more information about it here:

    http://www.ti.com/product/VCA810

    Another possibility is the LMH6503 variable gain amplifier (VGA):

    http://www.ti.com/product/LMH6503

    Both of these amplifiers have wide bandwidth and are completely usable at 100 kHz.

    Please note that these amplifiers are supported by the High-Speed Amplifier products group. If you have any questions about using one of these devices there is the High-Speed Amplifiers E2E froum where you can post your questions. They should be able to assist you.

    Regards, Thomas