AD606JN Analog Devices Inc, AD606JN Datasheet - Page 9

• Manufacturer Part Number: AD606JN
• Description: Amplifier IC
• Manufacturer: Analog Devices Inc

Specifications of AD606JN

• No. Of Amplifiers: 1
• Bandwidth: 50MHz
• No. Of Pins: 16
• Mounting Type: Through Hole
• Peak Reflow Compatible (260 C): No
• Leaded Process Compatible: No
• Package / Case: 16-DIP
• Rohs Status: RoHS non-compliant
• Amplifier Type: Logarithmic
• Number Of Circuits: 1
• Output Type: Differential
• Current - Input Bias: 4µA
• Current - Supply: 13mA
• Current - Output / Channel: 1.2mA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• -3db Bandwidth: -
• Slew Rate: -
• Gain Bandwidth Product: -
• Voltage - Input Offset: -
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Low Frequency Applications
With reasonably sized input coupling capacitors and an optional
input low-pass filter, the AD606 can operate to frequencies as
low as 200 Hz with good log conformance. Figure 8 shows the
schematic, with the low-pass filter included in the dashed box.
This circuit should be built inside a die cast box and the signal
brought in through a coaxial connector. The circuit must also
have a low-pass filter to reject the attenuated RF signals that
would otherwise be rectified along with the desired signal and
be added to the log output. The shielded and filtered circuit has
a 90 dB dynamic range, as shown in Figure 9.
In this circuit, R4 and R5 form a 20 dB attenuator that extends
the input range to 10 V rms. R3 isolates loads from VLOG.
Capacitors C1 and C2 (4.7 F each), R1, R2, and the AD606’s
input resistance of 2.5 k form a 100 Hz high-pass filter that is
before the AD606; the corner frequency of this filter must be
well below the lowest frequency of interest. In addition, the
offset-correction loop introduces another pole at low signal
levels that is transformed into another high-pass filter because it
is in a feedback path. This indicates that there has to be a
gradual transition from a 40 dB roll off at low signal levels to a
20 dB roll off at high signal levels, at which point the feedback
low pass filter is effectively disabled since the incoming signal
swamps the feedback signal.
REV. B
INPUT
AC
DIECAST BOX
ATTENUATOR
453
R4
51.1
20dB
R5
Figure 8. Circuit for Low Frequency Measurements
4.7 F
4.7 F
C1
C2
+
+
100
100
LOW-PASS
680pF
R2
R1
FILTER
C3
–9–
This low-pass filter introduces some attenuation due to R1 and
R2 in conjunction with the 2.5 k input resistance of the
AD606. To minimize this effect, the value of R1 and R2 should
be kept as small as possible–100
ances the need to reduce the attenuation as mentioned above
with the requirement for R1 and R2 to be much larger then the
impedance of C1 and C2 at the low-pass corner frequency, in
our case about 1 MHz.
Figure 9. Performance of Low Frequency Circuit at 100 Hz
and 1 kHz to 10 MHz (Note Attenuation)
0.1 F
NC
4
3
2
1
0
AD606JN
–80
NC
NC
4.7 F
C4
–60
1kHz – 10MHz
NC = NO CONNECT
–40
INPUT SIGNAL – dBm
1k
R3
–20
90dB
100Hz
is a good value since it bal-
TO
DVM
0
+5V
20
AD606
40
3.5V