Measurement Setups and Additional Screenshots - Linear CMOS RF Power Amplifiers for Wireless Applications - page 129

Table 9.2 List of material
used in the 2-tone
measurement setup

Material Description

SMIQ06B [ 16 ] RF signal generator

FSIQ7 [ 15 ] RF signal analyzer

LC534AM [ 12 ] Oscilloscope

HP33250A [ 4 ] Function generator

E018-06.D [ 8 ] DC voltage source

Fluke 45 [ 9 ] Bench-top digital multimeter

Fluke 85 [ 10 ] True-rms handheld digital multimeter

CP015 [ 13 ] Current probe

K251 [ 6 ] Coaxial bias-tee

ZN2PD-9G [ 14 ] Coaxial power splitter

SUCOFLEX 104 [ 11 ] Coaxial cable (SMA)

with a frequency equal to half of the desired tone spacing, 0 V offset, and an am-
plitude that is varied so that the power of the tones can be swept. The output of the
function generator is connected to the “I” input of the RF signal generator. The RF
signal generator is configured to output a vector modulated signal at the desired RF
frequency. In this vector modulation, the signal at its “I” input modulates the RF
carrier—which is set for the maximum power and kept fixed—producing at the out-
put an amplitude modulated signal whose spectrum consists of two tones centered
at the RF carrier frequency and having a space between them equal to double the
modulation frequency (function generator signal frequency). This 2-tone spectrum
is the same of that obtained from a double sideband suppressed carrier (DSBSC)
AM system [ 7 , Chap. 9]. This strategy for generating 2-tone signals is useful when
two RF signal generators are not available.
The 2-tone signal is split in two signals using a coaxial power splitter. These sig-
nals are fed to the PA and to the envelope detector. The processed envelope from the
ENV board is provided to the MAIN board through a coaxial SMB cable. The total
current consumed by the PA and modulator comes from the VDD power supply and
are measured with the true-rms handheld digital multimeter. The dynamic supply
signal is monitored with the LC534AM oscilloscope which is also used to monitor
the current being consumed by the PA through the clamp-on current probe CP015.
The RF output is connected to the signal analyzer FSIQ7 and both the output power
and the IMD3 are measured.
Essentially the same setup is used in the 2-tone measurements for the frequency-
tunable system characterization. The main differences are that just one evaluation
board is used, no power splitter is needed, and the PA supply voltage and current do
not need to be monitored with an oscilloscope.