TSH346
Power supply considerations and improvement of the PSRR
Figure 22. Circuit for noise rejection improvement measurement
S
R
+5 V
T - bias
Coil
CHF
+
CLF
50 7
TSH346
50 7
AGILENT
4395A
A
AM00825
Figure 23 shows how the power supply noise rejection evolves versus frequency depending
on how carefully the power supply decoupling is achieved.
Figure 23. Power supply noise rejection
0
Vcc=5V(dc)+0.2Vp-p(ac)
-10 Decoupling capacitor: 10µF+100nF
Load=150Ω
-20 Noise rejection=20 log (ΔVCC/ΔVout)
-30
no coil
-40
-50
-60
-70
coil=560µH
-80
10k
100k
1M
10M
Frequency (Hz)
100M
9/18