Tomomi Research Inc.

RF Power Amplifier Tutorial (1)

2016/07/20Seong-Hun Choe

Tomomi Research Inc.

Gain

Power Amplifier (PA)

Gain (G) Pin Pout

𝐺 [𝑑𝐵 ]=10 𝑙𝑜𝑔10 (電力比 )=10 𝑙𝑜𝑔10( 𝑃𝑜𝑢𝑡

𝑃 𝑖𝑛)

10 dB

-3dB

Tomomi Research Inc.

Gain written as a voltage

Let R1 = R2

Tomomi Research Inc.

Gain written as a Current

Let R1 = R2

Tomomi Research Inc.

Gain Summary

ExpressionPower [dB]

Voltage [dB]Current [dB]

Tomomi Research Inc.

Transitor Data Sheet2sC3356 (Renesas Electronics)

http://jp.rs-online.com/web/p/bipolar-transistors/7724980/

トランジスタの入力側（ Base)にインピーダンス整合回路を設けずに、 50Ohmの信号発生器から 1GHzの信号を入力すると、(0.26)^2*100 = 6.8%の電力の反射が起こることを意味

http://amplet.tokyo/tu/pdf/2sc3356.pdf

Tomomi Research Inc.

Transitor Data Sheet2sC3356 (Renesas Electronics)

http://jp.rs-online.com/web/p/bipolar-transistors/7724980/

トランジスタの出力側（ Collector)にインピーダンス整合回路を設けずに、 50Ohmの信号発生器から 1GHzの信号を入力すると、 (0.266)^2*100 = 7.1%の電力の反射が起こることを意味

http://amplet.tokyo/tu/pdf/2sc3356.pdf

Tomomi Research Inc.

Transitor Data Sheet2sC3356 (Renesas Electronics)

http://jp.rs-online.com/web/p/bipolar-transistors/7724980/

トランジスタに電源を供給し、インピーダンス整合回路を設けずに、 50Ohmの信号を入力すると、 10log(3.744)^2=11.5 dBの利得（ゲイン）があることを意味する。

http://amplet.tokyo/tu/pdf/2sc3356.pdf

Tomomi Research Inc.

Transitor Data Sheet2sC3356 (Renesas Electronics)

http://jp.rs-online.com/web/p/bipolar-transistors/7724980/

トランジスタの出力側（ Collector)にインピーダンス整合回路を設けずに 50Ohm系の信号発生器から 1GHzの信号を入力すると、 10Log(0.236)^2=-17.3dBが減衰してトランジスタの入力側 (Base)に出力されることを意味する。http://amplet.tokyo/tu/pdf/2sc3356.pdf

Tomomi Research Inc.

dB( デシベル）： 物理量のレベルを表す単位。無次元量である。dBm : 電力を表す単位である。要は Watt に変換ができる単位。 dB と混同しないように注意。0 [dBm] = 1 [mW]

dBmと dB

Power [mW] Power [dBm]

1 mW 0dBm=

10 mW 10dBm=

100 mW 20dBm=

1W 30dBm=

10W 40dBm=

Tomomi Research Inc.

dBm と GainPower Amplifier (PA)

Gain (G)= 25 [dB]

Pin= 1 mW Pout= ?

Pout[dBm] = Pin [dBm] + Gain [dB] = 0 [dBm] + 25 [dB] = 25 [dBm] = 10 ^ (25/10) = 316.22 [mW]

Tomomi Research Inc.

dBm と Gain

Power [mW] Power [dBm]

1 mW 0dBm=

10 mW 10dBm=

100 mW 20dBm=

1W 30dBm=

10W 40dBm=

http://www.ebay.com/itm/182194447106?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Tomomi Research Inc.

この表でゲインを計算（次のページ）

http://www.ebay.com/itm/141841663164?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Tomomi Research Inc.

14 MHzinput

power [W]input power

[Vpp]output

power [W]output power

[Vpp] 　 Gain at 14 MHz [Power]

Gain at 14 MHz[Voltage ]

0.5 14.2 9.7 60.4 　 12.88 12.57 1 20 18.5 83.2 　 12.67 12.38 2 28 33 110 　 12.17 11.88 3 35 46 128 　 11.86 11.26 4 40 54 141 　 11.30 10.94 5 45 60 148 　 10.79 10.34

5.3 46 64 151 　 10.82 10.32

7 MHzinput

power [W]input power

[Vpp]output

power [W]output power

[Vpp] 　 Gain at 7MHz [Power]

Gain at 7 MHz [Voltage ]

0.1 6.3 1.66 26.6 　 12.20 12.51 0.5 14 27 104 　 17.32 17.42 1 20 55 146 　 17.40 17.27 2 28 93 196 　 16.67 16.90 3 35 106 208 　 15.48 15.48 4 40 112 213 　 14.47 14.53 5 45 114 214 　 13.58 13.54

Tomomi Research Inc.

0 1 2 3 4 5 60

2

4

6

8

10

12

14

16

18

20

12.88 12.67 12.17 11.86 11.30 10.79 10.82 12.20

17.32 17.40 16.67 15.48

14.47 13.58

Gain at 7MHz [Power] Gain at 14 MHz [Power]

input power [W]

Gain

[dB]

0 1 2 3 4 5 60

20

40

60

80

100

120

9.718.5

33

4654

6064

1.66

27

55

93

106112 114

output power at 7MHz [W]

output power at 14 MHz [W]

input power [W]

Out

put p

ower

[W]

Input power vs. Output powerこれがまっすぐだと Linear Ampと呼ばれる Input powerによる Gainの変化。まあまあまっすぐ

Tomomi Research Inc.

Efficiency definitions in RF Power Amplifier

Matching Network

Matching Network Load

Driver Pin

Pout

Pdc

+Vdc

L

Gain : Gp

Tomomi Research Inc.

Collector Efficiency

𝜂𝑐𝑜𝑙𝑙𝑒𝑐𝑡𝑜𝑟=𝑃𝑜𝑢𝑡

𝑃𝑑𝑐

Bipolar transistors (BJTs)Po : the RF output powerPdc: the input power supplied by the DC supply to the collector(Pdc = Vdc*Idc)

Gain : Gp

Tomomi Research Inc.

OVERALL Efficiency

𝜂𝑜𝑣𝑒𝑟𝑎𝑙𝑙=𝑃𝑜𝑢𝑡

𝑃 𝑖𝑛+𝑃𝑑𝑐

𝑃𝑜𝑢𝑡=𝐺𝑝𝑃 𝑖𝑛

𝜂𝑜𝑣𝑒𝑟𝑎𝑙𝑙=𝑃𝑜𝑢𝑡

𝑃𝑜𝑢𝑡

𝐺𝑝+𝑃

𝑑𝑐

Gain, P_out, P_dcだけで、効率を表す。Gain : Gp

Tomomi Research Inc.

POWER ADDED efficiency

𝜂𝑃𝑜𝑤𝑒𝑟 𝑎𝑑𝑑𝑒𝑑=𝑃𝑜𝑢𝑡−𝑃 𝑖𝑛

𝑃𝑑𝑐

𝑃𝑜𝑢𝑡=𝐺𝑝𝑃 𝑖𝑛

Gain, P_out, P_dcだけで、効率を表す。

𝜂𝑃𝑜𝑤𝑒𝑟 𝑎𝑑𝑑𝑒𝑑=𝑃𝑜𝑢𝑡−

𝑃𝑜𝑢𝑡

𝐺𝑝

𝑃 𝑑𝑐

Gain : Gp

Tomomi Research Inc.

Example100W

150W

Gain , Gp = 10

equation Value

Collector efficiency 66.7% = 100/150

Overall efficiency 62.5%=100/(100/10+150)

Power added efficiency 60%=(100-100/10)/150

Tomomi Research Inc.

Power output Capability

Matching Network Load

Pout

Pdc

+Vdc

L

Gain : Gp Vc,pk

Ic,pk

Collectorからいくら電力が取り出せるかを表すパラメータThe output power produced when the device has a peak collector voltage of 1[V] and a peak collector current of 1 [A].

𝐶𝑃=𝑃𝑜𝑢𝑡

𝑁 𝐼𝐶 ,𝑝𝑘𝑉 𝑐 ,𝑝𝑘

Cp : power output capabilityPout : output power [W]N : number of transistors in parallel or push pull designIc,pk : the peak collector current[A]Vc,pk : the peak collector voltage [V]

Important for cost effective design

Tomomi Research Inc.

ExampleA single ended class E circuit : Theoretical power output capability Cp, class E = 0.0981

The designed the peak collector voltage Vc,pk = 100 [V]The peak current will be

𝐶𝑃=𝑃𝑜𝑢𝑡

𝑁 𝐼𝐶 ,𝑝𝑘𝑉 𝑐 ,𝑝𝑘

𝐼𝐶 ,𝑝𝑘=𝑃𝑜𝑢𝑡

𝑁 𝐶𝑃,𝑉 𝑐 ,𝑝𝑘

10.19 [A] = 100 / (1 * 0.0981 * 100)