キーワード: rf, rf ic, pa, power amplifiers, wireless ics, gsm, edge, rf circuit, rf ics, PAs, rfics, power amplifier 関連製品
アプリケーションノート1829
The MAX2265 Is Ideal for EDGE Base-Station Pre-Driver Applications
Jan 09, 2003
Abstract: This application note presents measured performance data for the MAX2265 power amplifier (PA) when used for EDGE 8PSK modulation. +18.5dBm power was obtained in the 925MHz to 960MHz band. With a 5V power supply, 340mA were used to provide EVM better than 1%.
Many GSM operators are beginning to install 2G networks to support higher data rates, addressing the expected demands of mobile-phone users. EDGE, which stands for "Enhanced Data Rates for GSM Evolution," essentially triples the existing GSM data rate from 1-bit/symbol GMSK (gaussian minimum shift key) modulation to 3 bits/symbol 8PSK (phase shift key) while operating in the same occupied channel bandwidth.
The newly adopted modulation scheme of 8PSK requires a highly linear amplifier to minimize spectral regrowth and phase distortion. Power amplifiers for base station applications impose even more stringent requirements for its pre-driver to present a pristine signal with minimum non-linearity. As usual, the pre-driver must be electrically and thermally stable with good reliability for this application.
The MAX2265 is an excellent low-cost bipolar solution for GSM/EDGE base station down link pre-driver applications. Performance specifications are presented in this application note. Measured data indicates that the MAX2265 meets or exceeds requirements with margin.
Table 1. EDGE Pre-Driver Specification and MAX2265 Measured Data
Parameter
Customer
Spec
Measured
Data
Units
Reference/Notes
Supply Voltage
5.0
5.0
V
-
Supply Current
-
340
mA
POUT = +18.5dBm
Frequency Range
925 - 960
925 - 960
MHz
-
POUT
+17.5
+18.5
dBm
EDGE Mode
Gain
20
24.5
dB
-
Spurious at 400kHz offset
-70
-71
dBc
Measured in 30kHz BW
Spurious at 600kHz offset
-80
-83
dBc
Measured in 30kHz BW
EVM (average)
1
0.98
%
-
Figure 1. EDGE modulation spectrum plot at 960MHz and +18.5dBm POUT.
Figure 2. EDGE EVM at 960MHz and +18.5dBm output power.
