HPMX-2005 Datasheet, PDF (10/12 Pages) Agilent(Hewlett-Packard) – Silicon Bipolar RFIC 100 MHz Vector Modulator

HPMX-2005 Modulation
Spectrum Diagrams
Figure 30, below, shows the test
set-up that was used to generate
the GSM, JDC and NADC modula-
tion spectrum diagrams that ap-
pear on the following page. The
major differences between these
tests are summarized in the table
below.
The modulation spectra are cre-
ated by setting the function gen-
erator to the appropriate bit-clock
frequency. The pattern generator
is set to produce a pseudorandom
serial bit stream (n = 20) that is
NRZ coded. The pseudorandom
bit stream which simulates the se-
rial data in a digital phone is fed
to the base-band processor that
splits it into a two bit parallel
stream (I and Q) and then filters
each according to the require-
ments of the digital telephone sys-
tem being simulated. The I and Q
signals from the baseband filter
are then DC offset by 2.5 V using
the op-amp circuit. The output of
the modulator is monitored using
a spectrum analyzer.
System
GSM
JDC
NADC
Bit Clock Frequency
270 kHz
42 kHz
48.6 kHz
Baseband Filter
0.3 GMSK (HP-8657B)
α = 0.5 π/4 DQPSK (HP-8657D)
α = 0.35 π/4 DQPSK (HP-8657D)
Channel (LO) Frequency
900 MHz
950 MHz
835 MHz
7-63