Stanford Research Systems SR865A, Operation Manual

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158 Advanced Filters Appendix A
SR865A DSP Lock-in Amplifier
Frequency Response Graphs
These graphs illustrate the frequency response of the different filters at 12 and 24 dB/oct.
Each stage of the Gaussian filter has the same ENBW as a single stage of the RC filter.
Each stage of the Linear Phase filter has the same roll-off as a single stage of the RC
filter.
-80
-60
-40
-20
0
Response (dB)
0.1 1 10 100
Frequency (f
c
)
12dB/oct
RC
Gaussian (FIR)
Linear Phase
Gaussian
23dB better
rejection
Advanced filters
more bandwidth
-160
-140
-120
-100
-80
-60
-40
-20
0
Response (dB)
0.1 1 10 100
Frequency (f
c
)
24dB/oct
RC
Gaussian (FIR)
Linear Phase
Advanced filters
more bandwidth
Gaussian
46dB better
rejection