The same trick was used in many Nokia phones. Probably the most extreme instance of this is one HW revision of 5110, where the final RF PA stage consists of sin

The same trick was used in many Nokia phones. Probably the most extreme instance of this is one HW revision of 5110, where the final RF PA stage consists of single NPN transistor in common emitter circuit connected directly to battery terminals (other HW variants have HP power amplifier IC in the same place, but still, powered straight from the battery)