800 MHz, Linear-in-dB VGA with AGC Detector Data Sheet AD8368 FEATURES FUNCTIONAL BLOCK DIAGRAM VPSO MODE VPSO VPSI VPSI VPSI VPSI VPSI Analog variable gain range: 12 dB to +22 dB 10 21 9 11 12 22 23 13 Linear-in-dB scaling: 37.5 dB/V ICOM 16 AD8368 3 dB bandwidth: 800 MHz VGAIN = 0.5 V OCOM 6 Integrated rms detector GAIN 1 GAIN INTERPOLATOR FIXED-GAIN OUTPUT 24 ENBL AMPLIFIER BUFFER P1dB: 16 dBm 140 MHz OCOM 7 8 OUTP Output IP3: 33 dBm 140 MHz g STAGES m 3 HPFL Noise figure at maximum gain: 9.5 dB 140 MHz 0dB 2dB 4dB 36dB 4 DECL Input and output impedances: 50 REF 19 INPT 14 DECL 50 Single-supply voltage from 4.5 V to 5.5 V 17 ICOM DECL 15 DECL 2 RoHS-compliant, 24-lead LFCSP X ICOM 18 ATTENUATOR LADDER + ICOM 20 2 5 APPLICATIONS DETO DETI Complete IF AGC amplifiers Figure 1. Gain trimming and leveling Cellular base stations Point-to-point radio links RF instrumentation GENERAL DESCRIPTION The AD8368 is a variable gain amplifier (VGA) with analog By connecting MODE to ground and using the on-board rms linear-in-dB gain control that can be used from low frequencies detector, the AD8368 can be configured as a complete to 800 MHz. Its excellent gain range, conformance, and flatness automatic gain control (AGC) system with RSSI. The output are attributed to the Analog Devices, Inc., X-AMP architecture, power is accurately leveled to the internal default setpoint of 63 mV rms (11 dBm referenced to 50 ), independent of the an innovative technique for implementing high performance variable gain control. waveform crest factor. Because the uncommitted detector input is available at DETI, the AGC loop can level the signal at The gain range of 12 dB to +22 dB is scaled accurately to the AD8368 output or at any other point in the signal chain 37.5 dB/V with excellent conformance error. The AD8368 has over a maximum input power range of 34 dB. Furthermore, the a 3 dB bandwidth of 800 MHz that is nominally independent setpoint level can be raised by dividing down the output signal of gain setting. At 140 MHz, the OIP3 is 33 dBm at maximum before applying it to the detector. gain. The output noise floor is 143 dBm/Hz, which corresponds to a 9.5 dB noise figure at maximum gain. The single-ended The AD8368 operates from a supply voltage of 4.5 V to 5.5 V and consumes 60 mA of current. It can be fully powered down input and output impedances are nominally 50 . to <3 mA by grounding the ENBL pin. The AD8368 is fabricated The gain of the AD8368 can be configured to be an increasing using the Analog Devices proprietary SiGe SOI complementary or decreasing function of the gain control voltage depending bipolar IC process. It is available in a 24-lead LFCSP and on whether the MODE pin is pulled to the positive supply or operates over the industrial temperature range of 40C to to ground, respectively. When MODE is pulled high, the +85C. Application boards are available upon request. AD8368 operates as a typical VGA with increasing gain. Rev. C Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 20062017 Analog Devices, Inc. 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Technical Support www.analog.com 05907-001AD8368 Data Sheet TABLE OF CONTENTS Features ............................................................................................ 1 Fixed-Gain Stage and Output Buffer ..................................... 12 Applications ..................................................................................... 1 Output Offset Correction........................................................ 12 Functional Block Diagram ............................................................ 1 Input and Output Impedances ............................................... 12 General Description ....................................................................... 1 Gain Control Interface ............................................................ 13 Revision History ............................................................................. 2 Applications Information ............................................................ 14 Specifications ................................................................................... 3 VGA Operation ........................................................................ 14 Absolute Maximum Ratings .......................................................... 5 AGC Operation ........................................................................ 14 ESD Caution ................................................................................ 5 Stability and Layout Considerations ...................................... 16 Pin Configuration and Function Descriptions ........................... 6 Evaluation Board .......................................................................... 17 Typical Performance Characteristics ........................................... 7 Outline Dimensions ..................................................................... 19 Circuit Description ....................................................................... 12 Ordering Guide ........................................................................ 19 Input Attenuator and Interpolator ......................................... 12 REVISION HISTORY 9/2017Rev. B to Rev. C Changed CP-24-3 to CP-24-7 ...................................... Throughout Updated Outline Dimensions ....................................................... 19 Changes to Ordering Guide .......................................................... 19 9/2008Rev. A to Rev. B Added Stability and Layout Considerations Section ................. 16 Changes to Evaluation Board Section, Figure 40, and Table 6 .............................................................................................. 17 Added Figure 41, Figure 42, Figure 43, and Figure 44 Renumbered Sequentially .............................................................. 18 Added Exposed Pad Notation to Outline Dimensions ............. 19 10/2007Rev. 0 to Rev. A Changes to Table 1 ............................................................................ 3 Changes to Figure 4 to Figure 6 ...................................................... 7 Changes to Figure 16 ........................................................................ 9 Changes to Figure 31 ...................................................................... 12 Updated Outline Dimensions ....................................................... 18 Changes to Ordering Guide .......................................................... 18 4/2006Revision 0: Initial Version Rev. C Page 2 of 20