lhlbluesky
Banned
for basic BANDGAP core (VBE+deta(VBE) structure using two bjt, a resistor, two PMOS, an opamp to force Vip=Vin), how to analyze the PSRR+ (vref/vdd)? in my simulation, in 300KHz or so, two poles appear (close to each other), and the PSRR+ becomes positive, that is, vo/vdd>1 in some frequency range (300K ~ 600K), why? what is the possible reasons? why can PSRR+ be positive?
besides, in some process, cascode opamp can not be used in the above bandgap (especially NMOS cascode due to body effect), because leakage can decrease the output resistance of opamp, so gain decreases also. i want to ask, what is the leakage path of NMOS cascode transistor due to body effect? and why leakage is related to NMOS body effect? is the leakage current caused by parasitic diode or bjt(npn or pnp)?
thanks.
besides, in some process, cascode opamp can not be used in the above bandgap (especially NMOS cascode due to body effect), because leakage can decrease the output resistance of opamp, so gain decreases also. i want to ask, what is the leakage path of NMOS cascode transistor due to body effect? and why leakage is related to NMOS body effect? is the leakage current caused by parasitic diode or bjt(npn or pnp)?
thanks.