Extending talk time through improved transmitter efficiency

Abstract

Take any cellular or SMR handset and the standby time will exceed the talk time by at least a factor of 10. More specifically, the power consumed by the transmit circuitry during a call will typically be three to four times that used in receive. Dominating the transmit power consumption is the RF amplifier ("PA"), a component whose efficiency today is at best 55% (i.e. approx. half the PA battery drain is wasted as heat) and more typically only 30% to 40% for CDMA and TDMA handsets. Techniques for improving PA efficiency will therefore have the single greatest impact on improving talk time in all handset designs. This paper describes the front line candidates for increasing amplifier efficiency, (in some cases beyond 70%), and provides measurement and simulation data from test units.