AD8307AR-REEL(1999) 查看數據表（PDF） - Analog Devices
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AD8307AR-REEL Datasheet PDF : 20 Pages
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AD8307
Link No.
LK1
Default Position
A
LK2
Open
LK3
Open
LK4
Open
LK5
Open
Table II. Evaluation Board Link Options
Function
Power Up/Power Down. When this link is in position B, the ENB pin is connected to ground,
putting the AD8307 in power-down mode. Placing this link in position A connects the ENB
pin to the positive supply, thereby putting the AD8307 in normal operating mode.
Intercept Adjust. When Pin LK2 is left open, the AD8307 has a nominal logarithmic
intercept of –84 dBm. Putting LK2 in place connects the wiper of potentiometer R2 to Pin 5
(INT). By varying the voltage on INT, the position of the intercept can be adjusted. The inter-
cept varies by about 8 dB/V.
Slope Adjust. When this link is open, the nominal slope of the output is 25 mV/dB. Putting this
link in place connects a ground referenced 12.5 kΩ load resistor (R3) to the logarithmic out-
put. The parallel combination of this resistor and an internal 12.5 kΩ resistor reduces the
logarithmic slope to 12.5 mV/dB. R3 may be adjusted for other scaling factors.
Corner Frequency of Low-Pass Demodulating Filter. When this link is open, the corner fre-
quency of the low pass post demodulation filter has a nominal value of 4 MHz. This is set by
an on-chip load impedance of 12.5 kΩ and an on-chip load capacitance of 3.5 pF. The load
capacitance (e.g., of an oscilloscope probe) must be added to this capacitance, and will lower
the internal video bandwidth, to a nominal 1 MHz for a total of 13.5 pF. Putting LK4 in place
connects an external load capacitance (C5) of 0.1 µF to the output, reducing the corner fre-
quency of the low-pass filter to about 125 Hz. For large values of C5, the corner frequency can
be calculated using the equation, f ≈ 12.7 Hz/C5 (µF).
Offset Control Loop. When this link is open, the internal offset control loop gives the circuit an
overall high pass corner frequency of about 1 MHz. With LK5 link in place, a 1 nF capacitor
(C6) is connected to the OFS pin, reducing the high pass corner frequency to allow accurate
operation down to 10 kHz. To reduce the minimum operational frequency even further, a
larger capacitor can replace C6 (e.g., a 1 µF capacitor allows operation down to 10 Hz). Note
that that external capacitor C6 has no effect on the minimum signal frequency for input levels
that exceed the offset voltage (typically 400 µV). The range for such signals extends down to dc
(for signals applied directly to the input pins).
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic DIP
(N-8)
8-Lead SOIC
(SO-8)
0.430 (10.92)
0.348 (8.84)
8
5
0.280 (7.11)
0.240 (6.10)
1
4
0.325 (8.25)
PIN 1
0.060 (1.52)
0.300 (7.62)
0.210 (5.33)
0.015 (0.38)
MAX
0.130
0.160 (4.06)
0.115 (2.93)
(3.30)
MIN
0.022 (0.558) 0.100 0.070 (1.77)
0.014 (0.356) (2.54) 0.045 (1.15)
SEATING
PLANE
BSC
0.195 (4.95)
0.115 (2.93)
0.015 (0.381)
0.008 (0.204)
0.1968 (5.00)
0.1890 (4.80)
8
0.1574 (4.00)
0.1497 (3.80) 1
5
0.2440 (6.20)
4 0.2284 (5.80)
PIN 1
0.0098 (0.25)
0.0040 (0.10)
0.0688 (1.75)
0.0532 (1.35)
0.0196 (0.50)
؋ 45؇
0.0099 (0.25)
SEATING
PLANE
0.0500 0.0192 (0.49)
(1.27) 0.0138 (0.35)
BSC
0.0098 (0.25)
0.0075 (0.19)
8؇
0؇ 0.0500 (1.27)
0.0160 (0.41)
–20–
REV. A
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