Sequential broadband doherty power amplifier with adjustable output power back-off

Patent metadata

Field	Value
Publication number	US-2016268976-A1
Application number	US-201415027037-A
Country	US
Kind code	A1
Filing date	Oct 1, 2014
Priority date	Oct 5, 2013
Publication date	Sep 15, 2016
Grant date	—

Abstract

The invention relates to a sequential broadband Doherty power amplifier with adjustable output power back-off The sequential broadband Doherty power amplifier has at least one input (I 1 , I 2 ; RF in ) for receiving at least one broadband HF signal, wherein the broadband HF signal or broadband HF signals (RF in ) have at least an average power level (carrier/average) and a peak envelope power level (peak), with the average power level and the peak envelope power level defining a crest factor, and a first amplifier branch for amplifying the input signal, with the first amplifier branch providing the amplification substantially for the low and at least the average power level, at least one second amplifier branch for amplifying the input signal, wherein the second amplifier branch substantially provides the amplification for the peak envelope power level, wherein the output of the first amplifier branch is connected via an impedance inverter (Z T ) to the output of the second amplifier branch, the junction (CN) being connected to the load (Z 0 ) in a substantially directly impedance-matched manner, wherein the first and the second amplifier branch each have a supply voltage, with at least one of the supply voltages being variable as a function of the crest factor of the signal to be amplified, and wherein the signal propagation delay through the at least two amplifier branches is substantially identical in the operating range.

First claim

What is claimed is:

1 . A sequential broadband Doherty power amplifier with adjustable output power back-off, having
at least one input (I 1 , I 2 ; RF in ) for receiving at least one broadband HF signal, wherein the broadband HF signal or the broadband HF signals (RF in ) have at least an average power level (P avg ) and a peak envelope power level (PEP), wherein the average power level (P avg ) and the peak envelope power level (PEP) define a crest factor C=PEP/P avg , a first amplifier branch for amplifying the input signal (I 1 ), with the first amplifier branch substantially providing the amplification for the low and at least the average power level (P avg ), at least one second amplifier branch for amplifying the input signal (I 2 ), with the second amplifier branch substantially providing the amplification for the peak envelope power level (PEP), wherein the output of the first amplifier branch is connected via an impedance inverter (Z T ) to the output of the second amplifier branch, with the junction (CN) being connected to a load (Z 0 ) in a substantially directly impedance-matched manner, wherein the first amplifier branch and the second amplifier branch each have a supply voltage, with at least one of the supply voltages being variable as a function of the crest factor of the signal to be amplified, and wherein the signal propagation delay through the at least two amplifier branches is substantially identical in the operating range.

2 . The sequential broadband Doherty power amplifier as set forth in claim 1 , wherein the output impedance (Z C ) detected by the first amplifier branch corresponds approximately to the following formula relationship:

Z
c

=

{

Z
T
2

Z
0

@


BO

Z
T
2

α




Z
0

@


PEP

,

where BO refers to the operating mode in output power back-off and PEP to the operating mode at peak envelope power (PEP), and

α
=

1
+

I

p

sat

I

c

sat

·

V

DD
,
p

-

V

k
,
p

V

DD
,
c

-

V

k
,
c

can be derived from the currents I p|sat , I c|sat of the respective amplifier branches in the case of saturation of the respective amplifier branch and the respective supply voltages V DD,p , V DD,c of the amplifier branches and the knee voltages V k,p , V k,c of the respective amplifier branches.

3 . The sequential broadband Doherty power amplifier as set forth in claim 1 , having exactly one input for receiving a broadband HF signal or several broadband HF signals (RF) and at least one power splitter (DIV) for distributing the broadband HF signal or the several broadband HF signals to the first amplifier branch and the second amplifier branch.

4 . The sequential broadband Doherty power amplifier as set forth in claim 1 , wherein the impedance inverter (Z T ) makes a phase shift of a quarter wavelength available.

5 . The sequential broadband Doherty power amplifier as set forth in claim 1 , wherein the output impedance (Z p ) detected by the second amplifier branch corresponds approximately to the following formula relationship:

Z
p

=

{

∞

@


BO

β




Z
0

@


PEP

Assignees

• Rwth Aachen

Inventors

• Negra Renato
• Nghiem Xuan Anh

Classifications

• H03F1/0288 Primary

  using a main and one or several auxiliary peaking amplifiers whereby the load is connected to the main amplifier using an impedance inverter, e.g. Doherty amplifiers · CPC title

• H03F1/0211 Primary

  with control of the supply voltage or current · CPC title

• H03F2201/3233

  Adaptive predistortion using lookup table, e.g. memory, RAM, ROM, LUT, to generate the predistortion · CPC title

• H03F3/245

  with semiconductor devices only · CPC title

• H03F3/193

  with field-effect devices (H03F3/195 takes precedence) · CPC title