MF8CCJ National Semiconductor, MF8CCJ Datasheet - Page 10

• Manufacturer Part Number: MF8CCJ
• Manufacturer: National Semiconductor

Specifications of MF8CCJ

• Architecture: Switched Capacitor
• Cutoff Frequency: 20KHz
• Dual Supply Voltage (typ): ±5V
• Power Supply Requirement: Single/Dual
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Package Type: MDIP
• Lead Free Status / RoHS Status: Not Compliant

Figure 5 shows the MF8’s internal operational amplifier and
1 0 Application Information
1 4 MULTIPLE FEEDBACK LOOP CONFIGURATION
The multi-loop approach to building bandpass filters is high-
ly flexible and stable yet uses few external components
two second-order filter stages with three external resistors
in a fourth-order multiple feedback configuration Higher-or-
der filters may be built by adding more second-order sec-
tions and feedback resistors as in Figure 6 The filter’s re-
sponse is determined by the clock frequency the clock-to-
center-frequency ratio the ratios of the feedback resistor
values and the Qs of the second-order filter sections The
design procedure for multiple feedback filters can be broken
down into a few simple steps
1) Determine the characteristics of the desired filter This
will depend on the requirements of the particular applica-
tion For a given application the required bandpass re-
sponse can be shown graphically as in Figure 7 which
shows the limits for the filter response Figure 7 also makes
use of several parameters that must be known in order to
design a filter These parameters are defined below in terms
of Figure 7
FIGURE 5 General fourth-order multiple-feedback bandpass filter circuit MF8 pin numbers are shown
FIGURE 6 By adding more second-order filter stages and feedback resistors
higher order multiple-feedback filters may be built
(Continued)
10
FIGURE 7 Graphical representation of the amplitude
filter’s response should fall within the shaded area
response specifications for a bandpass filter The
TL H 8694– 13
TL H 8694 – 15
TL H 8694 – 14