RF AMPLIFIER OF ACCURATE BIAS AND HEALTHY HEADROOM AND METHOD THEREOF

A method operates to bias an RF receiver by incorporating a first NMOSFET as a common-source amplifier; incorporating a second NMOSFET as a cascode device stacked upon the first NMOSFET, injecting a reference current into a drain of a third NMOSFET; using a first operational amplifier to generate a first bias voltage to control a gate of the first NMOSFET, a gate of the third NMOSFET, and a gate of a fourth NMOSFET in accordance with a voltage difference between the drain of the third NMOSFET and a drain of the fourth NMOSFET; incorporating a fifth NMOSFET stacked upon the fourth NMOSFET; and using a second operational amplifier to generate a second bias voltage to control a gate of the second NMOSFET and a gate of the fifth NMOSFET in accordance with a voltage difference between a reference voltage and the drain of the fourth NMOSFET.