Digital Signal Processing Reference
In-Depth Information
Chapter 4
Measurement Results for the Dynamic Supply
CMOS RF Power Amplifie
Abstract
This chapter presents the experimental characterization of the dynamic
supply CMOS RF power amplifier whose design was the subject of Chap. 3. The
integrated circuit occupies an area of 1
.
35 mm
2
. The circuit was designed for an op-
erating frequency of 5.2 GHz, but measurements were also performed at 2.4 GHz.
Two-tone measurement results at 2.4 and 5.2 GHz showed that the system can de-
liver over 16 dBm (40 mW) linear output power with efficiencies of 22.7% and
12.6%, respectively. Compared to a constant 2.5 V supply operation, the power am-
plifier operating with the dynamic supply delivers higher linear output power. More-
over, a relative efficiency improvement of a factor of 2.3 at 2.4 GHz and of a factor
of 1.6 at 5.2 GHz at low output power levels is achieved. OFDM measurements
at 2.4 GHz demonstrated that for an EVM lower than 3% and for an equal output
power of 11 dBm (12.6 mW), the absolute improvement in efficiency is over 3.2%.
4.1 Introduction
We begin this chapter by describing the printed-circuit board designed for the evalu-
ation of the circuits. This board is necessary because the dynamic supply RF power
amplifier requires some circuit components that were not integrated, namely, the
input and output impedance matching networks, three bias current sources, the LC
filter at the output of the modulator, and decoupling capacitors. Then we proceed to
the characterization of the high-speed, high-efficiency modulator in Sect.
4.3
and the
PA in Sect.
4.4
. Once these two fundamental blocks are characterized, we present
the measurement results of the complete dynamic supply system in Sect.
4.5
.
4.2 Main Evaluation Board
A Printed-Circuit Board (PCB) was designed and fabricated for the evaluation of the
dynamic supply RF power amplifier. A special RF laminate, Rogers RO4350 [
25
],
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