Page 6-2 of the following has a schematic of a flyback with a UC3901 isolated feedback generator
Page 6-12 onwards explains the feedback loop.
**broken link removed**
...however, i am unable to write down the poles and zeros of the error amplifier transfer function......as i am confused by the UC3901 and the details about the modulator.
In the error amplifier transfer function, is the only part that gives phase change that part with the 1n5 cap near the UC3901?