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What is the reason for the using transconductance amplifier for the error amp in buck

GARAM AN
Intellectual 2010 points


Hello,

Can you explain why there is used transconductance amplifier for the error amp in the buck converter current mode?

Op amp can be used for the error amp in current mode buck converter?

The transconductance amplifier can be used in the voltage mode buck converter?

Thank you

  • 0
    TI__Expert 3645 points

    Hello,
    Generally speaking, OTA (transconductance amplifier) is preferred in integrated solutions since all the passives (integrated) of the compensation network are referred to ground, in this way also the parasitic effects are minimized. OTA has also higher bandwidth.
    However, OFA (feedback amplifier) is preferred for discrete applications.
    The main reason is that the OTA requires high output impedance that is easier to provide in integrated solutions (for example connecting the gate of mos). Particular attention is required to the parasitic effect of the passives especially on the negative terminal (OFA) since they can add a pole and cause oscillation.
    The selection between OTA and OFA is independent of the control topology.