A High Power-Added-Efficiency 2.5-GHz Class

A High Power-Added-Efficiency 2.5-GHz Class
Journal of Computer and Communications, 2016, 4, 74-78
Published Online March 2016 in SciRes. http://www.scirp.org/journal/jcc
http://dx.doi.org/10.4236/jcc.2016.43011
A High Power-Added-Efficiency 2.5-GHz
Class-F Power Amplifier Using 0.5 μm GaN
on SiC HEMT Technology
Chia-Han Lin1, Hsien-Chin Chiu1, Min-Li Chou1, Hsiang-Chun Wang1, Ming-Feng Huang2
1
Department of Electronic Engineering, Chang Gung University, No. 259, Wenhua 1st Rd., Guishan Dist.,
Taoyuan City 33302, Taiwan
2
JMIC, 16F., No.44, Sec. 2, Zhongshan N. Rd., Zhongshan Dist., Taipei City 104, Taiwan
Received 22 December 2015; accepted 26 February 2016; published 2 March 2016
Abstract
This paper proposed the high-frequency, multi-harmonic-controlled, Class-F power amplifier (PA)
implemented with 0.5 μm GaN Hetrojunction Electron Mobility Transistor (HEMT). For PA design
at high frequencies, parasitics of a transistor significantly increase the difficulty of harmonic manipulation, compared to low-frequency cases. To overcome this issue, we propose a novel design
methodology based on a band-reject, low-pass, output matching network, which is realized with
passive components. This network provides optimal fundamental impedance and allows harmonic control up to the third order to enable an efficient Class-F behavior. The implemented PA exhibits performance at 2.5 GHz with a 50% PAE, 14 dB gain, and 10 W output power.
Keywords
GaN, High Power, Class-F
1. Introduction
In modern wireless communication systems, RF power amplifiers (PAs) are one of the most important part of
the transmitters. Increasing the system efficiency, it is necessary that the PA is highly efficient as it is the most
power hungry device. High efficiency of a PA means low power consumption, less cooling requirement, which
reduce the overall cost of the RF front-ends as well. The original and novel design methodology schematic of
class-F power amplifier is shown in Figure 1 and Figure 2. When the waveform of Vmax is too large, it may
cause electric crystal burned limit, greatly reduces our ideas to make the design of the circuit. In order to improve this situation, we made the reinforcement foe class-F power amplifier circuit especially. At the output port,
a λ/4 microstrip lines were used which operating frequency ω0 as Figure 1 shown. This schematic allows the
odd-order harmonic signals are retained in the drain terminal, and even order harmonics signals were shorted to
ground, and this design allows the drain terminal of the voltage waveform is adjusted to a square wave, avoid
Vmax impact caused by too much.
How to cite this paper: Lin, C.-H., Chiu, H.-C., Chou, M.-L., Wang, H.-C. and Huang, M.-F. (2016) A High Power-AddedEfficiency 2.5-GHz Class-F Power Amplifier Using 0.5 μm GaN on SiC HEMT Technology. Journal of Computer and Communications, 4, 74-78. http://dx.doi.org/10.4236/jcc.2016.43011
C.-H. Lin et al.
Figure 1. Original design methodology schematic of class-F power
amplifier.
Figure 2. Novel design methodology schematic of class-F power
amplifier.
The principle of class-F power amplifier is retained by an infinite number of odd-order harmonics signal
waveform reshape using to produce the desired square-wave to improve the drain terminal of the voltage waveform, that if you do not use the microstrip line to achieve this result, there are other ways to solve. Figure 2
shows an important answer, that is to use multiple sets of LC resonant circuit for the output matching network.
Which can storage energy at fixed operating frequency, will affect the larger signal waveform reservations. As
for the other less important signals are ignored on the power loss less area and the resonant circuit. For example,
in Figure 2, this circuit only adds a LC resonant at 3ω0, and in Figure 3, though the wave drain terminal voltage
waveform has a little difference compare to the ideal square wave, but in inhibition of drain terminal Vmax has
significant performance. From this, when the odd harmonic signals richer, more connected composite waveform
approximates a square wave, and the more conversion efficiency. In theory, more than the increase in the output
of 5ω0 even 7ω0 resonant circuit, will contribute to better performance characteristics of the class-F power amplifier.
2. Circuit Design
The chip photograph is shown in Figure 4, only including input matching network where the passive components were arranged on the chip with dc and rf pads. And full schematic is shown in Figure 5. We used RC resonant to solving low frequency oscillation in rf input matching. The complete device small/large-signal modeling for HEMTs and passive components had been built for circuit simulation. The size of the chip is 1500 ×
1000 μm2, and the gate width for M is 12 × 100 μm2. And the output matching network is on PCB with wire
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C.-H. Lin et al.
Figure 3. Waveform of class-F power amplifier.
Figure 4. Chip photograph of the proposed PA.
VD
C6
VG
L4
C4
C3
C5
L3
RF input
L1
L2
L6
L7
C8
A
M
RF output
L5
C1
C7
R1
C2
Figure 5. Schematic of the class-F power amplifier.
bonding as Figure 6 shown. It presents that is used LC band-reject structure 3f0 and low-pass filter for f0, that in
order to reducing the loss from the effect of dc load. In the measurement setup, a off-chip inductor to be rf choke
was used through bonding wire at the output port.
3. Experiment Result
The dc biases for first-stage amplifier are VD = 28 V and VG = −2.5 V. Figure 7 shows the result measured and
simulated small-signal return loss curves. The signal source for large-signal performance measurement was
generated by Agilent E8257D Signal Generator. The output signal of the PA was measured by Agilent E4440A
spectrum analyzer. We made S22 return loss at higher about 500 MHz than S11. Because when VD = 28 V and
VG = −2.5 V, the transistor is on cutoff region. And when at the signal source for large-signal, the transistor will
be into saturation. Then the output port will occur parasitics capacitance, it will make the return loss close to the
lower frequency. Figure 8 shows the curves of output power, power gain and PAE as a function of the input
power at the frequency of 2.5 GHz. The maximum output of 40 dBm with PAE of 62% can be achieved in simulation. And the measured output power was limited with lower PAE performance about 50%. Figure 9 exhibits the curves of saturated output power and gain versus frequency for measurement.
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C.-H. Lin et al.
Figure 6. Output matching network of the class-F power amplifier.
Return Loss(dB)
0
-2
-4
-6
-8
-10
-12
-14
-16
-18
-20
S11 Simulation
S22 Simulation
S11 Measurement
S22 Measurement
0
1
2
3
Freq(GHz)
4
5
50
70
40
60
50
30
40
20
30
10
20
meas. sim.
0
10
-10
-20
PAE(%)
Output Power(dBm)&Gain(dB)
Figure 7. Return loss of the proposed class-F power amplifier.
0
0
5
10
15
20
25
30
-10
Input Power(dBm)
Figure 8. Large-signal performance of the proposed class-F
power amplifier.
Output Power(dBm)&Gain(dB)
45
40
35
30
25
Output Power
Gain
20
15
10
2.3
2.4
2.5
Freq(GHz)
2.6
2.7
Figure 9. Saturation output power and gain as a function of
frequency.
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C.-H. Lin et al.
Table 1. Performance comparison of reported power amplifiers using a GAN device.
Refs
Class
Freq (GHz)
Gain (dB)
Pout (dBm)
PAE (%)
[1]
F
3.1
15
40
82
[2]
F−1
3.37
14
39
76.9
[3]
F
2
12.7
40.7
70
[4]
EF
2.2
9.2
39.5
80
This work
F
2.5
14
40
50
4. Conclusion
This paper proposed class-F power amplifier in 0.5 μm GaN HEMT process. The input matching was designed
on-chip to reduce the PA module size. The measurement of power amplifier has a high power performance from
2.3 GHz to 2.7 GHz. The chip size is 1.5 × 1 mm2. The proposed power amplifier can be used for S-band communication system application. And the performance comparison is shown in Table 1.
References
[1]
Chen, K. and Peroulis, D. (2013) A 3.1-GHz Class-F Power Amplifier With 82% Power-Added-Efficiency. IEEE Microwave and Wireless Components Letters, 23, 436-438. http://dx.doi.org/10.1109/LMWC.2013.2271295
[2]
Kalim, D., Pozdniakov, D. and Negra, R. (2012) A 3.37 GHz Class-F−1 Power Amplifier with 77% PAE in GaN
HEMT Technology. Ph.D. Research in Mcroelectronics and Electronics (PRIME), 1-4.
[3]
Hwang, T., Lin, J., Azadet, K., Wilson, R.S., Kiss, P., Abdelli, S. and Laturell, D. (2013) Class-F Power Amplifier
with 80.1% Maximum PAE at 2 GHzJor Cellular Basestation Applications. IEEE 14th Annual on Wireless and Microwave Technology Conference (WAMICON), 1-3.
[4]
Thian, M., Barakat, A. and Fusco, V. (2015) High-Efficiency Harmoic-Peaking Class-EF Power Amplifiers with Enhanced Maximum Operating Frequency. IEEE Transactions on Microwave Theory and Techniques, 63, 659-671.
http://dx.doi.org/10.1109/TMTT.2014.2386327
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