Decibel gain dsb
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description
decibel
Transcript of Decibel gain dsb
Pengertian Gain, Attenuasi dan Decibels
Gain, attenuation, dan Decibel
• Gain = penguatan, atau dikatakan sebagai perbandingan output dan input dimana output lebih besar daripada input.
• Attenuation = redaman, dikatakan sebagai perbandingan output dan input dimana output lebih kecil daripada input.
• Decibel (dB): satuan ukuran yang dipakai untuk menyatakan Gain dan Attenuation.
Gain = amplification
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1. Berapa penguatan tegangan sebuah penguat yang menghasilkan tegangan keluaran 750 mV dari sumber masukan 30 V ?
2. The power output of an amplifier is 6 watts (W). The power gain is 80. What is the input power?
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3. Three cascaded amplifiers have power gain of 5, 2, and 17. The input power is 40 mW. What is the output power?
4. A two stage amplifier has an input power of 25 W and an output power of 1.5 mW. One stage has a gain of 3. What is the gain of the second stage?
Attenuation = redaman
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R2=100 3333.0300100
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A1=0,2 A2=0,9 A3=0,06
AT= A1 x A2 x A3 = 0.2 X 0.9 x 0.06 = 0.0108
Vout = AT Vin= 0.0324 = 32.4 mV
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R2=250A2 = 4
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Vin = 1.5 V Vout = 6.75 V0.15V 1.5V 0.45V
A1= 0.1 A2= 10 A3= 0.3 A4= 15
AT = A1 A2 A3 A4 = (0.1)(10)(0.3)(15) = 4.5
Contoh soal
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A voltage divider like that shown in Fig. 2-5 has values of R1 = 10 k and R2 = 470 .
a. What is the attenuation?
b. What amplifier gain would you need to offset the loss for an overall gain of 1 ?
AT = A1A2
where A1 is attenuation and A2 is the amplifier gain
Note: To find the gain that will offset the loss for unity gain, just takethe reciprocal of attenuation: A2 = 1/A1
Contoh soalAn amplifier has a gain of 45,000, which is too much for the application. With an input voltage of 20V, what attenuation factor is needed to keep the output voltage from exceeding 100 mV?
Let A1 = amplifier gain = 45,000; A2 = attenuation factor; AT = total gain.
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Decibel (dB)
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Formula (1) untuk menyatakan penguatan (gain) atau redaman (attenuation) tegangan dari suatu rangkaian.Formula (2) untuk penguatan atau redaman arusFormula (3) untuk penguatan atau redaman daya
It is common for electronic circuits and systems to have extremely high gains or attenuations, often in excess of 1 million.
Dengan mengubah angka di atas menjadi decibel (dB) akan membuatnya terkesan menjadi lebih kecil dan mudah digunakan.
Contoh
4.64)22.3(2067.1666log20003.05log20 dB
98.13)398.1(1004.0log10502log10
dB
a. An amplifier has an input of 3 mV and an output of 5 V. What is the gain in decibels?
b. A filter has a power input of 50 mW and an output of 2 mW. What is the gain or attenuation?
Note that when the circuit has gain, the decibel figure is positive. If the gain is less than 1, which means that there is an attenuation, the decibel figure is negative.
dB (decibel)
Adalah satuan factor penguatan jika nilainya positif, dan
pelemahan/redaman/loss jika nilainya negative.
Jika input = 1 watt, output = 100 watt maka terjadi
penguatan (G) 100 kali, maka G = 10 log 100/1 = 20 dB
Jika input = 100 watt, output = 50 watt maka terjadi
redaman/loss daya (G), maka G = 10 log 50/100 = -3 dB
( maka disebut redaman / loss 3 dB)
• dBW (Decibel Watt ) dan dBm adalah satuan level daya• dBW :adalah satuan level daya dengan referensi daya 1
watt P(dBW) = 10 Log P(watt)/1 wattdBm:adalah satuan level daya dengan referensi daya 1 mW = 10-3 watt
• P (dBm) = 10 Log P(watt)/10-3 watt• 10 Watt = P (dBW) = 10 Log 10 Watt/1 Watt (= 10 Log 10 = 10
dBW)• 1000 Watt = P (dBW) = 10 Log 1000 Watt /1 Watt (= 10 Log
1000 = 30 dBW)• 10 Watt = P(dBm) = 10 Log 10/10-3 = 10 Log 104 = 10*4 = 40
dBm• 100 Watt = P(dBm) = 10 Log 100/10-3 = 10 Log 105 = 10*5 =
50 dBm• 1000 Watt = P(dBm) = 10 Log 1000/10-3 = 10 Log 106 = 10*6
= 60 dBm
• Terlihat bahwa dari dBw ke dBm terdapat selisih 30 dBsehingga dapat dirumuskan :P (dBm) = P (dBW) + 30 atau, P (dBW) = P (dBm) – 30Contoh :1. Sebuah Amplifier mempunyai gain = 20 dB, jika diberi input 10
dBm berapa output amplifier tersebut? Jawab : Pout (dBm) = Pin(dBm) + G = 10 + 20 = 30 dBm.
2. Sebuah Amplifier dengan gain 30 dB, jika outputnya sebesar 45 dBm berapa level inputnya? Jawab : Pout(dBm) = Pin (dBm) + G =? Pin = Pout G = 45 - 30 = 15 dBm
3. Output amplifier sebesar 30 dBm akan dilewatkan kabel dengan redaman / loss 2 dB. Berapa level sinyal setelah melewati kabel?
Jawab : Pout = Pin L = 30 - 2 = 28 dBm
Lossstage
A1=15dB A2= - 20dB A3= 35dB
AT = A1 + A2 + A3
AT = 15 – 20 + 35 = 30 dB
gain gain ((redamanredaman)) total: total:
Antilog:
Contoh soal1. A power amplifier with a 40 dB gain has an output power of 100 W.
What is the input power?
2. A power amplifier has a gain of 60 dB. If the input voltage is 50V, what is the output voltage?
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dBm dan dB dBm adalah ratio logaritmik dengan acuan 1 mW untuk daya
dB adalah ratio logaritmik dengan acuan 1 Volt untuk tegangan
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Contoh:
1. Nyatakan 20 dBm dalam watt.
2. Nyatakan 40 dB dalam volt.
Daya = 100 mW
Tegangan = 100 V
Lossstage
A1= 30dB A2= - 10dB A3= 3dB
1mW ???
Contoh:
