Measurement Results for the Dynamic Supply CMOS RF Power Amplifie - Linear CMOS RF Power Amplifiers for Wireless Applications - page 50

4.5 Dynamic Supply RF PA Characterization

The dynamic supply RF power amplifier was characterized using the setup described
in Chap. 9 (Appendix A). It requires two evaluation PCBs: the board to which we
referred as the main evaluation board and an auxiliary board with the envelope de-
tection and processing circuits. The RF signal is split in two, using a power splitter,
with one signal going to the PA and the other to the envelope detector. Two-tone
measurements were used to verify the linearity and efficiency of the power ampli-
fier operating in the dynamic supply system and with a constant supply voltage.
Furthermore, measurements with an OFDM signal were also performed to evaluate
the system for application in WLANs.

4.5.1 Two-Tone Measurements

The 2-tone measurements were carried out with tones centered at 5.2 GHz and
spaced 500 kHz apart from each other. We used the RF signal generator SMIQ06B
[ 27 ] and the RF signal analyzer FSIQ7 [ 26 ]. Detailed information on the setup used
for this measurement are provided in Chap. 9 (Appendix A).
Figure 4.14 shows the measured power gain. Five curves are presented with four
of them for different cases of the constant supply operation, that is, 1 V to 2.5 V in
0.5 V steps. These curves were used to calibrate the envelope processing circuit to
set the dynamic supply voltage to a level just enough to result in amplification with-
out compression. The fifth curve ( thick line ) shows the dynamic supply PA power

Fig. 4.14 Measured 2-tone power gain at 5.2 GHz