Datasheet

Application information TSH343
12/17
3.2 PSRR and improvement of power supply noise rejection
Figure 28. Circuit for power supply bypassing
Figure 29 shows how the power supply noise rejection evolves versus frequency depending
on how carefully the power supply decoupling is achieved.
Figure 29. Power supply noise rejection
Criteria for choosing the ferrite:
● In DC, the resistance (R) of the ferrite must be as low as possible to keep +5V power
supply on the chip.
● In AC, along a 30MHz bandwidth (HD spectrum), the equivalent impedance (Z=R+jX)
must be as high as possible to optimize rejection of the noise generated by the power
supply.
50Ω
+5V
75Ω
TSH343
T-bias
AGILENT
4395A
S
R
A
L
C
LF
CHF
50Ω
+5V
75Ω
TSH343
T-bias
AGILENT
4395A
S
R
A
L
C
LF
CHF
100k 1M 10M 100M
-80
-70
-60
-50
-40
-30
-20
-10
0
L= Ferrite FBMJ4516HM900
CHF=100nF
CLF=10uF
PSRR
L=2uH
CHF=100nF
CLF=10uF
PSRR (dB)
Frequency (Hz)