Implementation

RPLY_BIAS

Top level. Two bipolars biased at different current density to create two different diode voltages. The difference in the diode voltage, which is proportional dVd = kT/q x ln(N) , across a resistor.

An OTA is used to force the resistor top voltage to be the same as the left diode voltage.

The proportional to absolute temperature (PTAT) current is determined by the dVd/R.

The PTAT current is copied by a cascoded current mirror to provide bias current to other blocks.

The T_OP and T_ON provides a scaled version of the dVd voltage. The absolute level of T_OP is adjusted to create a constant voltage over temperature

RPLYBS_OTAN

Current mirror OTA with NMOS input.

RPLYBS_CMPMOS

Includes a startup circuit for the bandgap to ensure that the output voltage will start at zero if there is no bias current.