Logarithmic scale
7
1 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 0 Logarithmic scale Linear scale A logarithmic scale compresses large values and allows a large range to be covered thout losing resolution for the smaller valu
description
0. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Linear scale. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Logarithmic scale. A logarithmic scale compresses large values and allows a large range to be covered without losing resolution for the smaller values. 40. 30. Cutoff Frequencies -3dB. - PowerPoint PPT Presentation
Transcript of Logarithmic scale
1
1 2 3 4 5 6 7 8 9 10
1 2 3 4 5 6 7 8 9 100
Logarithmic scale
Linear scale
A logarithmic scale compresses large values and allows a large range to be covered
without losing resolution for the smaller values.
40
Av db Linear scale
Frequency in Hz (log scale)10 100 1k 10k 100k 1Meg 10Meg
Cutoff Frequencies -3dB30
20
10
0
-10
-20
-30
-40
AvMid
20 db per decade rolloff
4
10 Hz 100 Hz 1 kHz 10 kHz 100 kHz
50 dB
40 dB
30 dB
20 dB
10 dB
0 dB
Ideal Bode plot of a dc amplifier with two break frequencies.
20 dB/decade
40 dB/decade
fb1 fb2
5
R
C
Amplitude responseof RC lag circuit
0 dB
-20 dB
-40 dB
-60 dB
10f2f2 100f2 1000f2
f2 = RC1
f2
f( )
1+
1AV =
6
0o
0.1f2 f2 10f2
Angular responseof RC lag circuit
-90o
-45o
R
C
f2
f = -arctan
Phase angle is between 0 and 90 degrees
Angle(Av) degrees
Frequency in Hz (log scale)10 100 1k 10k 100k 1Meg 10Meg
Cutoff Frequencies -3dB(f2)90
45
0
-45
-90Change at -45degrees/decade
