SL531 [ETC]
250MHz TRUE LOG IF AMPLIFIER; 250MHz的真对数中频放大器
| 型号： | SL531 |
| 厂家： | 
ETC |
| 描述： | 250MHz TRUE LOG IF AMPLIFIER |
| 文件： | 总4页 (文件大小：97K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
ADVANCE INFORMATION
DS3608 - 2.0
SL531
250MHz TRUE LOG IF AMPLIFIER
The SL531 C is a wide band amplifier designed for use in
logarithmic IF amplifiers of the true log type. The input and log
output of a true log amplifier are at the same frequency i e
detection does not occur. In successive detection log
amplifiers (using SL521 SL1521 types) the log output is
detected.
The small signal gain is 10dB and bandwidth is over
500MHz. At high signal levels the gain of a single stage
dropstounity. A cascade of such stages give a close
approximation to a log characteristic at centre frequencies
between 10and 200MHz.
CM8
An important feature of the device is that the phase shift is
nearly constant with signal level. Thus any phase information
on the input signal is preserved through the strip.
The device is also available as the 5962-92084 which has
guaranteed operation over the full Military Temperature
Range and is screened to MIL-STD-883 Class B. Data is
available separately
Fig.1 Pin connections
FEATURES
■
■
■
Low Phase Shift vs Amplitude
On-Chip Supply Decoupling
Low External Components Count
APPLICATIONS
True Log Strips with:-
Log Range
Centre frequencies
Phase Shift
■
■
■
70dB
10 - 200MHz
± 0.5 degrees / 10dB
Fig.2 Circuit diagram
ABSOLUTE MAXIMUM RATINGS
(Non-simultaneous)
Supply voltage
Storage temperature range
+12 volts
-65°C to +150°C
Operating temperature range
-55°C to +125°C
See operating notes
175°C
Max junction temperature
Junction - ambient thermal resistance
220°C/Watt
Junction - case thermal resistance
80°C/Watt
CIRCUIT DESCRIPTION
Fig.3 Block diagram
The SL531 transfer characteristic has two regions For small
inputsignalsithasanominalgainof10dB. atlargesignalsthe
gain falls to unity (see Fig 7) This is achieved by operating a
limiting amplifier and a unity gain amplifier in parallel (see Fig
3) Tr1 and Tr4 comprise the long tailed pair limiting amplifier,
the tail current being supplied byTrS, see Fig 2 Tr2 and Tr3
form the unity gain amplifier the gain of which is defined by the
emitterresistorsTheoutputsofbothstagesaresummedinthe
300 ohm resistor and Tr7 acts as an emitter follower output
buffer. Important features are the amplitude and phase
linearity of the unity gain stage which is achieved by the use
of 5GHz transistors with carefully optimised geometries.
ORDERING INFORMATION
5962-92084 (SMD)
SL531 C CM
SL531
ELECTRICAL CHARACTERISTICS
These characteristics are guaranteed over the following condltions (unless otherwise stated)
Test circuit Fig (4)
Frequency 60MHz
Supply voltage 9 volts
Ambient temperature 22±2°C
Value
Characteristic
Conditions
Vin = -30dBm
Units
Min. Typ. Max.
Small signal voltage gain
High level slope gain
Upper cut off frequency
Lower cut off frequency
Supply current
Phase change with input amplitude
Input impedance
Output impedance
8
-1
10
0
12
+1
dB
dB
MHz
MHz
mA
250 500
3
17
1.1
10
25
3
-3dB w.r.t. ± 60MHz
degress
-Vin = 30dBm to +10dBm
f = 10 - 200MHz
2.pF parallel with 1kΩ
15Ω series with 25nH
OPERATING NOTES
1. Supply Voltage Options
3. Low Frequency Response
Anonchipresistorisprovidedwhichcanbeusedtodropthe
supply voltage instead of the external 180 ohms shown in the
test circuit. The extra dissipation in this resistor reduces the
maximum ambient operating temperature to 100°C. It is also
possibletousea6voltsupplyconnecteddirectly topins1and
2 Problems with feedback on the supply line etc may occur in
this connection and RF chokes may be required in the supply
line between stages.
The LF response is determined by the on chip capacitors. It
can be extended by extra external decoupling on pins 5 and
1.
2. Layout P recautions
The internal decoupling capacitors help prevent high
frequency instability however normal high frequency layout
precautions are still necessary. Coupling capacitors should
be physically small and be connected with short leads. It is
most important that the ground connections are made with
short leads to a continuous ground plane.
Fig.4 Test ciruit
Fig.5 Small signal frequency response
SL531
Fig.6 Phase v. input
TYPICAL APPLICATION—6 STAGE LOG STIP
Input log range OdBm to—70dBm
Low level gain 60dB (—70dBm in)
Output dynamic range 20dB
Phase shift (over log range) ±3°
Frequency range 10—200MHz
Fig.7 Transfer characteristics linear plot
The circuit shown in Fig 9 is designed to illustrate the use of
theSL531inacompletestripThesupplyvoltageisfedtoeach
stageviaanexternal180Ω resistortoallowoperationto125°C
ambient If the ambient can be limited to +100°C then the
internal resistor can be used to reduce the external
component count Interstage coupling is very simple with just
a capacitor to isolate bias levels being necessary. No
connection is necessary to pin 5 unless operation below
10MHz is required. It is important to provide extra decoupling
onpin1ofthefirststagetopreventpositivefeedbackoccuring
down the supply line. An SL560 is used as a unity gain buffer
the output of the log strip being attenuated before the SL560
to give a nominal 0dBm output into 50Ω.
Fig.8 Transfer characteristics logarithmic input scale
Fig.9 Circuit diagram 6 stage strip
SL531
HEADQUARTERS OPERATIONS
CUSTOMER SERVICE CENTRES
GEC PLESSEY SEMICONDUCTORS
Cheney Manor, Swindon,
Wiltshire SN2 2QW, United Kingdom.
Tel: (0793) 518000
• FRANCE & BENELUX Les Ulis Cedex Tel: (1) 64 46 23 45 Fax : (1) 64 46 06 07
• GERMANY Munich Tel: (089) 3609 06-0 Fax : (089) 3609 06-55
• ITALY Milan Tel: (02) 66040867 Fax: (02) 66040993
• JAPAN Tokyo Tel: (03) 5276-5501 Fax: (03) 5276-5510
Fax: (0793) 518411
• NORTH AMERICA Scotts Valley, USA Tel (408) 438 2900 Fax: (408) 438 7023.
• SOUTH EAST ASIA Singapore Tel: (65) 3827708 Fax: (65) 3828872
• SWEDEN Stockholm, Tel: 46 8 702 97 70 Fax: 46 8 640 47 36
• UK, EIRE, DENMARK, FINLAND & NORWAY
GEC PLESSEY SEMICONDUCTORS
P.O. Box 660017
1500 Green Hills Road,
Swindon Tel: (0793) 518510 Fax : (0793) 518582
Scotts Valley, California 95067-0017,
United States of America.
Tel: (408) 438 2900
These are supported by Agents and Distributors in major countries world-wide.
GEC Plessey Semiconductors 1994
Fax: (408) 438 5576
This publication is issued to provide information only which (unless agreed by the Company in writing) may not be used, applied or reproduced for any purpose nor form part of any order or contract nor to be regarded
as a representation relating to the products or services concerned. No warranty or guarantee express or implied is made regarding the capability, performance or suitability of any product or service. The Company
reserves the right to alter without prior knowledge the specification, design or price of any product or service. Information concerning possible methods of use is provided as a guide only and does not constitute
any guarantee that such methods of use will be satisfactory in a specific piece of equipment. It is the user's responsibility to fully determine the performance and suitability of any equipment using such information
and to ensure that any publication or data used is up to date and has not been superseded. These products are not suitable for use in any medical products whose failure to perform may result in significant injury
or death to the user. All products and materials are sold and services provided subject to the Company's conditions of sale, which are available on request.
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