ML13156 Datasheet, PDF (16/21 Pages) LANSDALE Semiconductor Inc. – Wideband FM IF System

ML13156
LANSDALE Semiconductor, Inc.
Legacy Applications Information
45 MHZ NARROWBAND RECEIVER
The above application examples utilize a 10.7 MHz IF. In this sec-
tion a narrowband receiver with a 455 kHz IF will be described.
Figure 21 shows a full schematic of a 45 MHz reciever that uses a
3rd overtone crystal with the on–chip oscillator transistor. The
oscillator configuration is similar to the one used in Figure 17; it is
called an impedance inversion Colpitts. A 44.545 Mhz 3rd over-
tone, series resonant crystal is used to achieve an IF frequency at
455 kHz. The ceramic IF filters selected are Murata Erie part #
SFG455A3. 1.2 kΩ chip resistors are used in series with the filters
to achieve the terminating resistance of 1.4 kΩ to the filter. The IF
decoupling is very important; 0.1 µF chip capacitors are used at
Pins 6, 7, 11 and 12. The quadrature detector tank circuit uses a
455 kHz quadrature tank from Toko.
The 12 dB SINAD performance is –109 dBm for a fmod = 1.0 kHz
and a fdev = ±4.0 kHz. The RSSI dynamic range is approximately
80 db of linear range (see Figure 22).
RECEIVER DESIGN CONSIDERATIONS
The curves of signal levels at various portions of the application
receiver with respect to RF input level are shown in Figure 26. This
information helps determine the network topology and gain blocks
required ahead of the MC13156 to achieve the desired sensitivity
and dynamic range of the receiver system. In the application circuit
the input third order intercept (IP3) performance of the system is
approximately –25 dBm (see Figure 27).
Figure 21. MC13156DW Application Circuit at 45 MHz
1.8 µH
+
(6)
1.0 µ
45 Hz
RF Input
33 p
(1)
0.33 µH
1
SMA _{180 p}
2
Mixer
10 n 1.2 k
3
(2) 455 kHz
Ceramic
Filter
4 VCC
Bias
10 n
24
56 p
23
(5) 0.416 µH
39 p _{10 k}
VEE 22
10 n
21
100 k
5
0.1 µ
6
0.1 µ
7
1.2 k
8
IF Amp
Data
Slicer
Bias
20
47 k
10 n
19
VEE
10 n
18
10 k
17
(2) 455 kHz
VCC
Ceramic
Filter
9 VCC
VEE ¹⁶
100 n
10
0.1 µ
11
0.1 µ
12
LIM Amp
5.0 p
15
14
1.0 n
13
100 k
100 k
470 k
(4) 3rd OT
XTAL
44.545
MHz
Carrier
Detect
RSSI
Output
Data Slicer
Hold
Data
Output
Audio To
C–Message
Filter and
Amp.
27 k 180 p
(3)
680 µH
VCC = 2.0 to 5.0 Vdc
NOTES: 1. 0.33 µH Variable Shielded Inductor: Coilcraft part # 7M3–331 or equivalent. ⁺
2. 455 kHz Ceramic Filter: Murata Erie part # SFG455A3.
3. 455 kHz Quadrature Tank: Toko part # 7MC8128Z.
4. 3rd Overtone, Series Resonant, 25 PPM Crystal at 44.540 MHz.
5. 0.416 µH Variable Shielded Inductor: Coilcraft part # 143–10J12S.
6. 1.8 µH Molded Inductor.
1.0 µ
Page 16 of 21
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