Patent ID: 7340228

Claim:
A radio frequency (RF) transmitter comprising: a radio-frequency (RF) power amplifier comprising a drive transistor capable of being coupled to an antenna, wherein said RF power amplifier is capable of receiving an input RF signal and generating an output RF signal for driving said antenna; and a drain bias adaptation circuit for supplying drain current to a drain of said drive transistor comprising: a first switch comprising a first terminal coupled to said drive transistor drain and a second terminal coupled to a system supply voltage having a level V system ; a second switch comprising a first terminal coupled to said drive transistor drain and a second terminal coupled to a high supply voltage having a level V high greater than V system ; a first bypass capacitor coupled to said second terminal of said first switch for reducing low-frequency signal components in said drain current when said first switch is closed and said second switch is open; and a second bypass capacitor coupled to said second terminal of said second switch for reducing low-frequency signal components in said drain current when said second switch is closed and said first switch is open.