transistor circuits xiv - electronicsย ยท transistor circuits xvi power amplifiers part i -...
TRANSCRIPT
![Page 1: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/1.jpg)
Transistor Circuits XVI
Power Amplifiers Part I -
Transformer-Coupled
![Page 2: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/2.jpg)
Basic configuration
![Page 3: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/3.jpg)
Things to know
โข ๐๐ = ๐๐ ๐๐
๐๐
2
โข Zp = Input impedance to the transformer
โข Zs = Load or speaker impedance
โข Np = Number of turns (windings) in the primary
โข Ns = Number of turns (windings) in the secondary โ Transformer efficiency โ 100%
![Page 4: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/4.jpg)
โข ๐๐ถ๐ธ โ ๐๐ถ๐ถ โ ๐ ๐ธ๐ผ๐ถ
โข DC resistance of primary turns โ 0ฮฉ (negligible).
![Page 5: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/5.jpg)
Circuit for all three examples
68kฮฉ 8.2kฮฉ
100ฮฉ
vs
18V
18VVBE = 0.6V
hFE = hfe = 100RL
Transformer
Np/Ns = 20:1
![Page 6: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/6.jpg)
First example problem
โข Find the dc base-to-ground voltage VB, collector-to-ground voltage VC, and emitter-to-ground voltage on the circuit shown. Assume that the dc resistance of the primary windings is negligible.
![Page 7: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/7.jpg)
First example work
โข ๐๐ต =๐ 2
๐ 1+๐ 2๐๐ถ๐ถ =
8.2kฮฉ
76.2kฮฉ18 = 1.937V
โข ๐๐ธ = ๐๐ต โ ๐๐ต๐ธ = 1.937 โ 0.6 =1.337V
โข ๐๐ถ = ๐๐ถ๐ถ = 18V
![Page 8: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/8.jpg)
Second example problem
โข If the load resistance is 8ฮฉ, what resistance does the signal current ic in the primary โseeโ in the circuit shown?
![Page 9: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/9.jpg)
68kฮฉ 8.2kฮฉ
100ฮฉ
vs
18V
18VVBE = 0.6V
hFE = hfe = 100RL
Transformer
Np/Ns = 20:1
![Page 10: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/10.jpg)
Second example work
โข ๐๐ = ๐๐ ๐๐
๐๐
2= 8 20 2 =
3.2kฮฉ
![Page 11: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/11.jpg)
Third example problem
โข In the circuit shown, let vo be the signal voltage across the primary turns of the transformer. What is the ratio vo/vs if the load on the secondary is an 8ฮฉ speaker? Hint: The impedance of the primary is like rL of a CE amplifier. Note that the emitter resistance is unbypassed.
![Page 12: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/12.jpg)
68kฮฉ 8.2kฮฉ
100ฮฉ
vs
18V
18VVBE = 0.6V
hFE = hfe = 100RL
Transformer
Np/Ns = 20:1
![Page 13: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/13.jpg)
Third example work
โข Since the impedance of the primary is like rL, we need to use the formula
๐ด๐ฃ =๐๐ฟ
๐๐โฒ+๐๐ธ
and then calculate the
value of reโ
![Page 14: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/14.jpg)
โข Zp = rL = 3.2kฮฉ; rE = 100ฮฉ
โข ๐ผ๐ธ =๐๐ธ
๐ ๐ธ=
1.337V
100ฮฉ= 13.37mA
![Page 15: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/15.jpg)
โข ๐๐โฒ =
25mV
๐ผ๐ธ=
25mV
13.37mA= 1.87ฮฉ
โ(Using 26mV we get 1.945ฮฉ)
โข ๐ด๐ฃ =๐๐ฟ
๐๐โฒ+๐๐ธ
=3.2kฮฉ
1.87ฮฉ+100ฮฉ=
3.2kฮฉ
101.87ฮฉ=
31.413
โ (Using 1.945ฮฉ for reโ yields a gain of 31.39)
![Page 16: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/16.jpg)
Any questions?
โข Contact us at:
โ 1-800-243-6446
โ 1-216-781-9400
โข Email:
![Page 17: Transistor Circuits XIV - Electronicsย ยท Transistor Circuits XVI Power Amplifiers Part I - Transformer-Coupled . Basic configuration. Things to know โข ๐๐=๐ ๐๐ ๐๐](https://reader030.vdocuments.net/reader030/viewer/2022040102/5f06fcdd7e708231d41abbde/html5/thumbnails/17.jpg)