XR-2212 データシートの表示（PDF） - Exar Corporation
部品番号
コンポーネント説明
メーカー
XR-2212 Datasheet PDF : 20 Pages
| |||
2
FM
Input
0.1mF
4
XR-2212
VCC
1 VCC
10
Phase
Detector
C1
16
9
7
RF
RC
11
0.1mF
R1
5
12
VCO
14
13
R0
CO
Rx Fine Tune
6
30pF
RL
5K
0.1mF
8
Demod
Output
Internal
Reference
Figure 11. Circuit Connection for FM Demodulation
Design Instructions
The circuit of Figure 11 can be tailored to any FM
demodulation application by a choice of the external
components R0, R1, RC, RF, C0 and C1. For a given FM
center frequency and frequency deviation, the choice of
these components can be calculated as follows, using the
design equations and definitions given on page 10.
a) Choose VCO center frequency f0 to be the same as
FM carrier frequency.
b) Choose value of timing resistor R0, to be in the range
of 10kW to 100kW. This choice is arbitrary. The
recommended value is R0 + 20kW. The final value
of R0 is normally fine-tuned with the series
potentiometer, RX.
c) Calculate value of C0 from design equation (1) or from
Figure 7:
C0 = 1/R0f0
d) Choose R1 to determine the tracking bandwidth, Df
(see design equation 5). The tracking bandwidth, Df,
should be set significantly wider than the maximum
input FM signal deviation, DfSM. Assuming the
tracking bandwidth to be “N” times larger than
DfSM, one can re-unite design equation 5 as:
Df
f0
+
R0
R1
+
N
DfSM
f0
Table 2. lists recommended values of N, for various
values of the maximum deviation of the input FM
signal.
e) Calculate C1 to set loop damping (see design
equation 4). Normally, ς = 1/2 is recommended.
Then, C1 = C0/4 for ς = 1/2.
Rev. 2.01
11
Share Link: 