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Original question:

TI AMC7904 Bias monitor and controller questions

TI AMC7904 can be used to control both LDMOS and GaN gate bias voltage by one device

Syed Mateen
Prodigy 40 points
Other Parts Discussed in Thread: AMC7904, LMP92066, AMC7904S

Can I use TI AMC7904 device to control both LDMOS and GaN Power amplifiers using one device. LDMOS gate bias requires positive voltage and GaN requires negative gate bias voltage. Please let us know whether we can configure AMC7904 to provide +ve gate bias voltage to LDMOS and -ve gate bias voltage to GaN amplifiers using one AMC7904 device.

Pl. let us know if you have any application circuit for this application.

Thanks,

Syed

  • 0
    TI__Guru 52753 points

    Erin will help with this.

  • 0 in reply to Paul_Frost
    Prodigy 40 points

    Hi Erin,

    I will ask the same question I asked for LMP92066 as I want to finalize the TI component selection for my design.

    Can I use  use one   AMC7904 device to control both GaN PA (-ve bias)  and LDMOS PA (+ve bias) ..

    Do I have to use two separate   AMC7904 devices as well, one for GaN PA and the second for LDMOS PA. Is my understanding correct.

    Regards,

    Syed

  • +1 in reply to Syed Mateen
    TI__Expert 4470 points

    Hi Syed,

    Unfortunately, the AMC7904 cannot bias both LDMOS and GaN by itself at the same time due to similar reasons as the LMP92066. 

    You can use external circuitry to shift the output of the AMC7904 to the other range, though. For example, if you were to power the AMC7904 in the negative range and use a differential opamp circuit, you could shift the output from n10-0V to 0-10V. An opamp would not likely be able to achieve the fast switching that the AMC7904 can implement, though, so if the fast switching is required you would need to implement discrete switches or use two AMC7904s. 

    Let me know if you have any further questions.

    Thanks,
    Erin