MX105ADW CMLMICRO [CML Microcircuits], MX105ADW Datasheet - Page 10

• Manufacturer Part Number: MX105ADW
• Description: Tone Detector
• Manufacturer: CMLMICRO [CML Microcircuits]

Tone Detector
5.10 Calculate Signal to Noise Performance
Worst-case S/N calculations depend on calculation of a value “M” using the formula shown below:
substituting example values,
By substituting this value for M in Figure 5, the minimum required S/N of an in band tone with respect to an adjacent
interfering tone can be found. This then has to be increased depending on the input tone amplitude.
The following formula expresses the reduction in noise immunity as the input signal approaches the detect filter sensitivity
V
If this S/N is better than required for the application, R3 C3
increased to obtain a faster tone detection time.
If the S/N performance is not adequate, the operating bandwidth can be reduced toward the MUBW, or R3C3
increased to improve S/N performance at the expense of slower response time.
5.11 Calculate C4 for 30° Phase Shift
Capacitor C4 is used to phase shift the input to the VCO commutating filter by 30°, thereby shifting the sampling clocks by
the same amount. This enables the Detect sampling filter to sample and integrate at the maximum and minimum of the
input tone.
© 1997 MX•COM, INC.
4800 Bethania Station Road, Winston-Salem, NC 27105-1201 USA
TH
.
www.mxcom.com Tele: 800 638 5577 910 744 5050 Fax: [phone]
-28
-24
-20
-16
-12
required
-8
-4
0
C4
Figure 5: S/N vs. BW Separation
Number of Bandwidths Separation
1
N
S
2
2
M
= 20log
tan(30 )
M
f
0
3 200 0 01
4
10
510 0.1
3 R2 C2
R
R3 C3
V
A
V
IN
can be reduced, or the operating bandwidth can be
V
6
f
IN
0
All trademarks and service marks are held by their respective companies.
0.092
.
V
A
TH
R
A
V
8 5
8
.
+
164pF
S
N
Figure 5
10
M =
M = 1
M = 0.1
M = 0.33
MX105A PRELIMINARY INFORMATION
Doc.# 20480133.003
A
can be