Application Note
AN4001
Application Note
300 Watt Class E Amplifier Using MRF151A
Rev. 01262010
60
40
m2
m1
PROTOTYPE
time= 29.97usec
Vout=-41.16 V
20
Before a prototype can be tested, the low value
load resistor must be matched to 50 ohm for use with
standard test equipment. A simple way of doing this is
by using a lumped element quarter wave as described
in [3] and shown here in Figure 7. The characteristic
impedance of this quarterwave section is given by:
0
m2
-20
-40
-60
time= 29.97usec
Vout=46.35 V
m1
29.95
29.96
29.97
29.98
29.99
30.00
time, usec
Zo = Zin Zout
(7)
Figure 5. AC voltage across the load resistor
For a load resistor R = 3 ohm the characteristic imped-
ance would be 12.25 ohm. For f = 81.36 MHz the com-
ponent values are L = 24 nH and C = 160 pF.
10
9
m6
8
7
The prototype is shown in Figure 8. The load
m6
6
inductors are the hair-pin type and are made of AWG10
copper wire. The inner diameter are 0.35” in both cases
and the lengths are 0.63” for 23nH and 0.97” for 24nH.
A vector network analyzer was used to measure the
inductance values and the length of the inductor was
adjusted until the desired values of 23 and 24 nH were
achieved. The recommended reactance value for the
drain RF choke is at least 10R or 30 ohm. This trans-
lates into LRFC > 60nH. This inductor has been built
using 12 turns of AWG 16 copper wire wound on an
Amidon T-157-6 iron powder torroid which provides
about 13uH of inductance. This is more than enough
to eliminate any contribution from the biasing network.
Some optimization of the load network was necessary
due to PCB parasitic capacitances and inductance er-
ror. The final value of the series resonant capacitor
was 174.1pF.
time= 29.97usec
5
4
3
2
1
0
I_Probe1.i=7.903 A
29.95
29.96
29.97
29.98
29.99
30.00
time, usec
Figure 6. DC current drawn from the power supply.
L
C
C
Zout
Zin
The performance of the prototype is shown in
Figure 7. Lumped element quarter wave section
Table 1 and Figure 9. At Pout = 300 watt, Eff = 82.1.
These numbers correlate well with simulated results of
319 watts with 84.1% efficiency. Power gain, on the
other hand is 13dB in the simulation but only 10.9dB
when tested. Since the SPICE model does not incor-
porate thermal effects a faster gain compression of the
prototype is to be expected. If higher gain is required it
can be achieved by a tradeoff in power and efficiency
as shown in Table 1. For example at Pout = 250 watt,
Gain = 14.2dB and Eff = 78.1, which is still a relatively
good number.
At Pout = 300 watt and Pin = 24.3 watt, power
added efficiency (PAE) is 77%. Dissipated power in
this case is 89.6 watts. Since the thermal resistance of
MRF151A is RθJC= 0.42 ºC/W the rise in junction tem-
perature is 37.6 ºC. Even with a case temperature of
85 ºC the junction temperature would be only ~123 ºC.
Figure 8. Prototype of class E amplifier
ADVANCED: Data Sheets contain information regarding a product M/A-COM Technology Solutions
is considering for development. Performance is based on target specifications, simulated results,
and/or prototype measurements. Commitment to develop is not guaranteed.
PRELIMINARY: Data Sheets contain information regarding a product M/A-COM Technology
Solutions has under development. Performance is based on engineering tests. Specifications are
typical. Mechanical outline has been fixed. Engineering samples and/or test data may be available.
Commitment to produce in volume is not guaranteed.
• North America Tel: 800.366.2266 • Europe Tel: +353.21.244.6400
• India Tel: +91.80.43537383
• China Tel: +86.21.2407.1588
Visit www.macomtech.com for additional data sheets and product information.
M/A-COM Technology Solutions Inc. and its affiliates reserve the right to make
changes to the product(s) or information contained herein without notice.
5秒后页面跳转
STM32H743技术深度剖析与应用案例探索
LM321中文资料解析：引脚功能介绍、技术特点、技术特性分析
74HC14芯片资料介绍：性能特性分析、引脚介绍
LM1875芯片手册：功放参数分析、引脚说明、电路设计要点
微信公众号
抖音公众号
浙公网安备 33010502006866号 浙ICP备10014259号-119
营业执照ICP证
数据手册
如果您发现信息不准确，
