Obsolescence Notice
This product is obsolete.
This information is available for your
convenience only.
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THIS DOCUMENT IS FOR MAINTENANCE
PURPOSES ONLY AND IS NOT
RECOMMENDED FOR NEW DESIGNS
ADVANCE INFORMATION
DS3606 - 2.0
SL521
150MHz WIDEBAND LOG AMPLIFIER
The SL521A, B and C are bipolar monolithic Integrated
circuit wideband amplifiers, intended primarily for use in
successive detection logarithmic IF strips, operating at centre
frequencies between 10MHz and 100MHz The devices
provide amplification, limiting and rectification, are suitable for
direct coupling and incorporate supply line decoupling The
mid-band voltage gain of the SL521 is typically12dB(4times)
The SL521A, B and C differ mainly in the tolerance of voltage
gain and upper cut-off frequency
The device is also available as the 5962-90792 which has
guaranteed operation over the full Military Temperature
Range and is screened to MIL-STD-883 Class B. Data is
available separately
CM8
Fig.1 Pin connections - bottom view
FEATURES
s
s
s
s
s
s
s
ABSOLUTE MAXIMUM RATINGS
Wide Defined Gain
4dB Noise Figure
Hlgh I/P impedance
Low O/Pi mpedance
165MHz Bandwidth
On Chip Supply Decoupling
Low External Component Count
(Non-simultaneous)
Storage temperature range
Operating temperature range
Chip operating temperature
Chip-to-ambient thermal resistance
Chip-to-case thermal resistance
Maximum instantaneous voltage at
Video output
Supply voltage
-65°C to +150°C
-55°C to +125°C
+175°C
225°C/W
65°C/W
+12V
+9V
ORDERING INFORMATION
SL521 A CM
SL521 B CM
SL521 C CM
5962-90792 (SMD)
APPLICATIONS
s
Logarithmic IF Strips wlth Gains up to 108dB and
Linearity better than 1dB
Fig.2 Circuit diagram SL521
SL521
ELECTRICAL CHARACTERISTICS
These characteristics are guaranteed over the following conditions (unless otherwise stated)
Temperature = +22°C + 2°C
Supply voltage = +6V
DC connection between input and bias pins.
Value
Min.
Typ.
Max.
12.5
1 2.7
13.0
12.7
13.0
13.3
Units
dB
dB
dB
dB
dB
dB
MHz
MHz
MHz
MHz
ns
mA
mA
mA
db/V
%/V
V rms
dB
mA
mA
mA
Vp-p
Conditions
Characteristic
Voltage gain, f = 30MHz
Circuits
A
B
C
A
B
C
A
B
C
ABC
ABC
A
B
C
ABC
ABC
ABC
A
B
C
Voltage gain, f = 60MHz
Upper cut-off frequency (Fig. 3)
Lower cut-off frequency (Fig. 3)
Propagation delay
Maximum rectified video output
current (Fig. 4 and 5)
Variation of gain with supply voltage
Variation of maximum rectified
output current with supply voltage
Maximum input signal before overload
Noise figure (Fig. 6)
Supply current
11.5
11 .3
11.0
11.3
11.0
10.7
150 170
140 170
130 170
5
2
1.00
0.95
0.90
0.7
25
1.8
12.5
12.5
11.5
1.9
4
15.0
15.0
15.0
1.2
10 ohms source, 8pF load
10 ohms source, 8pF load
10 ohms source, 8pF load
7
1.10
1.15
1.20
f = 60MHz, 0.5V rms input
5.25
18.0
18.0
19.0
See note below
f = 60MHz, Rs = 450 ohms
Maxiumum RF output voltage
Note: Overload occurs when the input signal reaches a level sufficient to forward bias the base-collector junction to TR2 on peaks.
Fig.3 Voltage gain v. frequency (typical)
Fig.4 Rectified output current v. input signal (typical)
SL521
Fig.6 Noise figure v. temperature (typical)
Fig.5 Maximum rectified output current v. temperature
(typical)
OPERATING NOTES
The amplifiers are intended for use directly coupled, as
shown in Fig 8.
The seventh stage in an untuned cascade will be giving
virtually full output on noise.
Noise may be reduced by inserting a single tuned circuit in
the chain As there is a large mismatch between stages a
simple shunt or series circuit cannot be used The choice of
network is also controlled by the need to avoid distorting the
logarithmic law; the network must give unity voltage transfer at
resonance A suitable network is shown in Fig 9. The value of
C1 must be chosen so that at resonance its admittance equals
the total loss conductance across the tuned circuit Resistor R1
may be introduced to improve the symmetry of filter response,
providing other values are adjusted for unity galn at
resonance.
A simple capacitor may not be suitable for decoupling the
output line if many stages and fast rise times are required.
Alternative arrangements may be derived, based on the
parasitic parameters given.
Values of positive supply line decoupling capacitor
requlred for untuned cascades are given below. Smaller
values can be used in high frequency tuned cascades.
Number of stages
6 or more
5
4
Minimum capacitance
30nF
10nF
Fig.7 Input admittance with open-circuit output (typical)
Fig.8 Direct Coupled amplifiers
3
3nF lnF
Fig.9 Suitable interstagetuned circuit
The amplifiers have been provided with two earth leads to
avoid the introduction of common ground lead inductance
between input and output circuits. The equipment designer
should take care to avoid the subsequent introduction of such
inductance.
The 500pF supply decoupling capacitor has a resistance
of, typically, 1 0Q. It is a junction type having a low breakdown
voltage and consequently the positive supply current will
increase rapidly if the supply voltage exceeds 7.5V (see
Absolute Maximum Ratings).
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