Datasheet

AD637
Rev. K | Page 13 of 20
dB CALIBRATION
Refer to Figure 20:
• Set V
IN
= 1.00 V dc or 1.00 V rms
• Adjust R1 for 0 dB out = 0.00 V
• Set V
IN
= 0.1 V dc or 0.10 V rms
• Adjust R2 for dB out = −2.00 V
Any other dB reference can be used by setting V
IN
and R1
accordingly.
AD707JN
+V
S
R2
5k
33.2k
R3
1k*
BUFFER
AD637
SQUARER/DIVIDER
FILTER
25k
25k
1
2
3
4
5
6
7
14
13
12
11
10
9
8
C
AV
–V
S
+V
S
+
BUFF
OUT
COMMON
OUTPUT
OFFSET
BUFF IN
NC
CS
DEN
INPUT
dB OUTPUT
V
IN
NC
1µF
V
OUT
+V
S
AD508J
+2.5 V
R1
500k
0dB ADJUST
10k
00788-020
4.7k
+V
S
–V
S
+V
S
SIGNAL
INPUT
dB SCALE
FACTOR
ADJUST
COMPENSATED
dB OUTPUT
+ 100mV/dB
–V
S
60.4
2
3
4
6
7
ABSOLUTE
VALUE
BIAS
SECTION
*1k + 3500ppm
SEE TEXT
NC = NO CONNECT
Figure 20. dB Connection