Power amplifier system

A method of operating a power amplifier system comprising an N number of transistors coupled together drain-to-source between a supply node and a fixed voltage node with N being a counting number, wherein a first one of the N number of transistors coupled nearest to the fixed voltage node, and a controller configured to control switches coupled between gates of the N number of transistors and a serial switch output terminal, the method comprising:

• selectively closing the switches by way of the controller to place the N number of transistors in the OFF-mode when an RF signal is not to be amplified by the first one of the N number of transistors;
• selectively opening the switches by way of the controller to place the N number of transistors in the ON-mode when the RF signal is to be amplified by the first one of the N number of transistors;
• and
• providing switch control voltage levels by way of the controller through the serial switch output terminal coupled to the gates of remaining ones of the N number of transistors, wherein the remaining ones are selectively operated as cascode devices in the ON-mode and as turned-off switches in the OFF-mode.

A wireless communication device comprising:

• a baseband processor;
• transmit circuitry configured to receive encoded data from the baseband processor and to modulate a carrier signal with the encoded data, wherein the transmit circuitry comprises:
• an N number of transistors coupled together drain-to-source between a supply node and a fixed voltage node with N being a counting number, wherein a first one of the N number of transistors coupled nearest to the fixed voltage node is configured to selectively operate as an amplifying device in an ON-mode, and remaining ones of the N number of transistors are configured to selectively operate as cascode devices in the ON-mode and to selectively operate as turned-off switches in an OFF-mode;
• and
• a controller configured to place the N number of transistors in the ON-mode when a radio frequency (RF) signal is to be amplified by the first one of the N number of transistors and to place the N number of transistors in the OFF-mode when the RF signal is not to be amplified by the first one of the N number of transistors, wherein the controller is further configured to provide switch control voltage levels through a serial switch output terminal selectively coupled to the gates of the remaining ones of the N number of transistors that are configured to selectively operate as cascode devices in the ON-mode and to selectively operate as turned-off switches in the OFF-mode;
• and
• at least one antenna coupled to the transmit circuitry to transmit the carrier signal.