I plan on using the TPS7H5008-SEP for a push pull converter and am looking into designing the control loop. In the past I have used voltage op-amps, but noticed that most controllers leverage a transconductance amplifier for type 2 compensation. I found this TI article partially explaining why. Article Link: Switch-mode power converter compensatin made easy. I am refering to this line on page 17:
"In a transconductance amplifier, there is no local feedback; therefore there is no virtual ground. You can no longer ignore the bottom resistor of the input divider, and gm can vary depending on the integrated circuit design. A transconductance amplifier is also well suited for Type II compensation."
Can you explain the no local feedback of the transconductance amplifier and how it is apparent in the voltage op amp? I am confused how there is no virtual ground, are the inputs to a transconductance amplifier not high impedance where they cannot sink any current?
It has been a minute since I have used an Op-Amp and can not remember the last time I saw a transconductance amplifier, so if you could break it down to a low level it would be much appreciated.