Operations Manual

Introduction to the MCPS2000 Family
MCPS2000 Operations Manual
Spectrian Proprietary -- See notice on first page
4
1.2.2 MCPS2000 Functional Description
To achieve the high level of linearity required to support multiple cellular carriers at
the minimum cost, the RF modules in the MCPS2000 use a single loop feed-forward
correction architecture with two amplification loops – the main loop, containing the
main amplifier, and the error loop, containing the error amplifier. The combination
of the two loops results in a signal in which the distortion products have been
cancelled, enabling highly linear operation of the amplifier.
RF Module Functional Block Diagram
1.2.2.1 Main Loop
The output of the main amplifier contains both the desired signal and Inter-
modulation Distortion (IMD) products. This signal is coupled off and combined with
the desired signal coupled off the preamplifier. The relative delay and phases of
these signals are adjusted so they combine to cancel out the desired signal, creating
an error signal composed of only the main amplifier IMD products.
1.2.2.2 Error Loop
The error signal is amplified in the error loop and then combined with the output of
the main amplifier containing both the desired signal and distortion products such
that the distortion products cancel. The error loop provides the adjustments
necessary so that the amplitude, phase and delay of both signals result in the desired
cancellation.
Main
Vector Mod
Driver
Amp
Main
Amp
Delay Filter
Output Module
Pilot
Generator /
Reciever
Cancellation
Controller
Carrier
Cancellation
Error
Vector Mod
Σ
τ
Preamplifier
Delay
Line
Error
Amp
RF Input
RF Output