A High Voltage Swing 1.9 GHz PA in Standard CMOS

A circuit technique for RF power amplifiers that reliably handle voltage peaks well above the nominal supply voltage is presented. To achieve this high-voltage tolerance the circuit implements switched-cascode transistors that yield reliable operation for voltages up to 7V at RF frequencies in a 2.5V CMOS process. Advantages of this include the possibility to use higherohmic load resistors. The impact of load resistances with higher ohmic values is two-fold. Firstly the demands on matching networks are loosened which translates into a higher efficiency for the matching network. Secondly the signal currents are lower which decreases the impact of any series resistance. A design of a 1.9 GHz power amplifier using the switched cascode approach was made. Simulations on the extracted layout of a single ended side showed 21 dBm of output power at a 25 ohm load with 21 % PAE. A layout improvement was estimated to result in 22 dBm at 30 % PAE.