MAX7490 Maxim, MAX7490 Datasheet - Page 16

• Manufacturer Part Number: MAX7490
• Description: Dual Universal Switched-Capacitor Filters
• Manufacturer: Maxim

Table 5. Cascading Identical Bandpass
Filter Sections
Dual Universal Switched-Capacitor Filters
The wideband noise of the filter is the total RMS value
of the device’s noise spectral density and is used to
determine the operating SNR. Most of its frequency
contents lie within the filter’s passband and cannot be
reduced with postfiltering. The total noise depends
mainly on the Q of each filter section and the cascade
sequence. Therefore, in multistage filters, the section
with the highest Q should be placed first for lower out-
put noise.
16
TOTAL SECTIONS
______________________________________________________________________________________
1
2
3
4
5
TOTAL BW
1.000 B
0.644 B
0.510 B
0.435 B
0.386 B
Wideband Noise
TOTAL Q
1.00 Q
1.55 Q
1.96 Q
2.30 Q
2.60 Q
In some designs, such as very narrow band filters, or in
modes where f
2nd-order sections with identical f
without multiple feedback. The total Q of the resultant
filter (Q
Q is the Q of each individual filter section, and N is the
number of 2nd-order sections. In Table 5, the total Q
and total bandwidth (BW) are listed for up to five identi-
cal 2nd-order sections. B is the bandwidth of each sec-
tion.
TRANSISTOR COUNT: 1439
TECHNOLOGY: BiCMOS
T
) is:
O
Total Q
cannot be tuned with resistors, several
T
= Q / (2
Multiple Filter Stages
Chip Information
N
- 1)
O
may be cascaded
1/2