AD608(RevB) Просмотр технического описания (PDF) - Analog Devices
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AD608 Datasheet PDF : 12 Pages
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AD608
Applications
Figure 22 shows the AD608 configured for operation in a digital
system at a 10.7 MHz IF. The filter’s input and output imped-
ance are parallel terminated using 330 Ω resistors and the con-
version gain is 24 dB. The RF port is terminated in 50 Ω; in a
typical application the input would be matched to a SAW filter
using the impedance data shown previously in Table I.
Figure 23 shows the AD608 configured for narrowband FM op-
eration at a 450 kHz or 455 kHz with an external discriminator.
The IF filter has 1500 Ω input and output impedances— the
input is matched via a resistive divider and the output is termi-
nated in 1500 Ω. The discriminator requires 1 V p-p drive from
a 1 kΩ source impedance, here provided by a gain-of-2.5 Class
A amplifier.
C1
1µF
LO INPUT
–16dBm
C2
100pF
R5
51.1Ω
1 VPS1
2 COM1
3 LOHI
4 COM2
PRUP 16
LMOP 15
VPS2 14
FDBK 13
RF INPUT
–95dBm
TO
–15dBm
C3
100pF
R6
C4
51.1Ω 100pF
BIAS POINT
AT VPOS/2
5 RFHI
COM3 12
6 RFLO
RSSI 11
7 MXOP
IFLO 10
8 VMID
IFHI 9
AD608
10.7MHz BPF Z = 330Ω
R1
330Ω
R2
330Ω
VPOS
SUPPLY
2.7V TO 5.5V
R4
47kΩ
LIMO
POWER-UP
3V CMOS
C7
18nF
LIMITER
OUTPUT
VPOS –1V
R3 ±200mV
100Ω
C6
10nF
RSSI OUTPUT
+0.2V TO +1.8V
(20mV/dB)
OFFSET-CONTROL
LOOP FILTER
BPF REVERSE
TERMINATION
IF BIAS POINT
DECOUPLING
C5
0.1µF
BPF
TERMINATION
Figure 22. Application at 10.7 MHz. The Bandpass Filter
Can Be a Toko Type SK107 or Murata Type SFE10.7
PRUP
+5V
GND
LOHI
C1 0.1µF
R1 C2
51.1Ω 1nF
RFHI
R2
51.1Ω
C3
1nF
C4
R3
1nF 374Ω
R7
1130Ω
JUMPER
1 VPS1
2 COM1
3 LOHI
4 COM2
5 RFHI
6 RFLO
7 MXOP
PRUP 16
LMOP 15
R16
47kΩ
C5 0.1µF
R14
8.66k
R13
402
Q1
VPS2 14
FDBK 13
C8 0.1µF R15
24.9k
R12
1k
COM3 12 R6
1kΩ
RSSI 11
IFLO 10
C9
0.2µF
R5 200Ω
C6 0.1µF RSSI
C11
0.1µF
F2
CR1
CR2
8 VMID
IFHI 9
AD608
F1
R4
1.5kΩ
F1: TOKO HCFM2–455B
F2: MURATA CFY455S
CR1, CR2: 1N60
Q1: 2N3906
R10
3.3kΩ
R8
1k
R9
C10
1k 0.01µF
C7
0.1µF
AUDIO
R11
3.3k
Figure 23. Narrowband FM Application at 450 kHz or 455 kHz
–10–
REV. B
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