Hybrid Digital/Analog Power Amplifier

摘要

The invention may be embodied in radio frequency power amplifier (RF-PA) predriver circuits employing a hybrid analog/digital RF architecture including a resynchronizing digital-to-analog convertor to drive an efficient high-power output stage suitable for driving standard high power amplifier (HPA) output devices. The hybrid analog/digital RF architecture retains the advantages of high digital content integration found in conventional Class-S architecture, while relaxing the performance requirements on the output transistors and on the bitstream generator. The resulting predriver circuit combines the VLSI integration benefits of digital designs with the extensibility to arbitrary output power levels characteristic of analog designs. The hybrid analog/digital driving circuit is well suited for use with analog and Class-S HPAs used in wireless communication systems, such as the Doherty type HPA.

主权项

1. A radio frequency predriver [12] for driving a high power radio frequency amplifier [14] in a transmission direction, comprising:
a bitstream generator [20] operative for receiving a baseband digital data signal [16] and a desired carrier frequency [18] and generating an input bitstream [21] at the desired carrier frequency encoding the digital data signal [16]; a low-jitter, low phase noise carrier frequency oscillator [26] operative for creating a master clock signal [25]; a resynchronizing digital-to-analog converter [24] operative for generating a resynchronized bitstream signal [27] encoding the digital data signal [16] based on the input bitstream [21] and the master clock signal [25]; a band pass filter [28] operative for generating a filtered bitstream signal [29] based on the resynchronized bitstream signal [27]; and a medium power amplifier [30] operative for generating an output bitstream [31] based on the filtered bitstream signal [29] configured to drive the high power radio frequency amplifier [14].