The Communication Systems and Networks Research Group at the University of Bristol is working on developing power amplifiers for multi-carrier, multi-band, and multi-standard communication systems. A key challenge is ensuring the amplifiers have high linearity to support these complex modulation schemes. The group is designing tunable matching networks and transmitters to allow power amplifiers to operate over wide frequency ranges and multiple bands simultaneously. Concurrent multi-band operation impacts the behavioral modeling of the amplifiers, with stronger memory effects observed at smaller frequency separations between bands compared to wider separations.

1. Communication Systems & Networks Research Group
Merchant Venturers Building, Woodland Road, Bristol. BS8 1TR
@BristolCSN http://www.bristol.ac.uk/engineering/research/csn
Communication Systems
and Networks Group
• Power Amplifiers (PA) needs to be able to operate for
• Multi-carrier.
• Multi-band.
• Multi-standard systems.
• Amplifiers must be highly linear.
RFMD’s RF3833 25W GaN Wide-
Band Power
ACPR Performance when Δf = 40MHz ACPR Performance when Δf = 150MHz..
Digital
90o
0o
:2 :4 :8
DAC
DAC
I
Q
To the receiver
PA
Duplexer
Alias
reject
Prescaler
Tx
Filter
VCO
Quadrature modulator
This can be part
of the test bed
A Tunable Transmitter for Frequency Agile
Radios
OMNPkg. ParasiticIMN
Zintrin (Frequency
independent)
Constant? And
frequency
dependent
50 Ohm
(Freq.
ind.)
Power Amplifier Design with tunable Matching
Networks
C1 C2
L
Analysis of Tunable Matching Networks
2.6 GHz
2.1 GHz
0.9 GHz
2nd Harmonics
Design and Linearisation of Broadband -
Reconfigurable RF Power Amplifiers
Output Matching for Re-configurable PA
Multichannel Power Amplifier Linearisation
Multiband Power Amplifier linearisation
System Block Diagram
The Impact of Channel Gap
K N Gebremicael , Eyad Arabi, Kevin Morris and M A Beach
Email: m.a.beach@Bristol.ac.uk or kevin.morris@bristol.ac.uk
Network Coverage
• Inductors replaced by lines
• Genetic algorithm used for
optimization
• Coverage of fundamental
and 2nd harmonic at 3
frequencies
C1
Z0 , Ɵ3 Z0 , Ɵ1 Z0 , Ɵ2
C2
C3
A reconfigurable or wideband PA is the key component
on a tunable transmitter
A tunable matching network can correct the effect of
the package at multiple frequencies
Concurrent multi-band operation impacts the behavioural
model:
• Therefore we must account for all carriers when
applying DPD.
• The spectral gap between the bands impacts the
model, with stronger memory effect at smaller Δf
than at wider Δf.
Aim: To develop amplifier technologies which are frequency agile, linear and efficient for 5G
and beyond applications, for both sub 6GHz and millimetre wave applications