Datasheet AD8368 (Analog Devices)

800 MHz, Linear-in-dB VGA with AGC Detector Data Sheet AD8368 FEATURES FUNCTIONAL BLOCK DIAGRAM Analog variable gain range: −12 dB to +22 dB VPSO MODE VPSO VPSI VPSI VPSI VPSI VPSI 10 21 9 11 12 22 23 13 Linear-in-dB scaling: 37.5 dB/V ICOM 16 3 dB bandwidth: 800 MHz @ VGAIN = 0.5 V AD8368 OCOM 6 Integrated rms detector GAIN 1 GAIN INTERPOLATOR FIXED-GAIN OUTPUT P1dB: 16 dBm @ 140 MHz 24 ENBL AMPLIFIER BUFFER OCOM 7 Output IP3: 33 dBm @ 140 MHz g 8 OUTP m STAGES Noise figure at maximum gain: 9.5 dB @ 140 MHz 3 HPFL 0dB –2dB –4dB –36dB Input and output impedances: 50 Ω 4 DECL INPT 19 REF Single-supply voltage from 4.5 V to 5.5 V 50Ω 14 DECL ICOM 17 – RoHS-compliant, 24-lead LFCSP DECL 15 DECL ICOM 18 ATTENUATOR LADDER X2 + ICOM 20 APPLICATIONS 2 5
001
DETO DETI
05907-
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 an innovative technique for implementing high performance 63 mV rms (−11 dBm referenced to 50 Ω), independent of the variable gain control. waveform crest factor. Because the uncommitted detector The gain range of −12 dB to +22 dB is scaled accurately to input is available at DETI, the AGC loop can level the signal at 37.5 dB/V with excellent conformance error. The AD8368 has the AD8368 output or at any other point in the signal chain a 3 dB bandwidth of 800 MHz that is nominally independent over a maximum input power range of 34 dB. Furthermore, the of gain setting. At 140 MHz, the OIP3 is 33 dBm at maximum setpoint level can be raised by dividing down the output signal gain. The output noise floor is −143 dBm/Hz, which corresponds before applying it to the detector. 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 input and output impedances are nominally 50 Ω. and consumes 60 mA of current. It can be fully powered down The gain of the AD8368 can be configured to be an increasing to <3 mA by grounding the ENBL pin. The AD8368 is fabricated or decreasing function of the gain control voltage depending using the Analog Devices proprietary SiGe SOI complementary on whether the MODE pin is pul ed to the positive supply or bipolar IC process. It is available in a 24-lead LFCSP and to ground, respectively. When MODE is pulled high, the operates over the industrial temperature range of −40°C to AD8368 operates as a typical VGA with increasing gain. +85°C. Application boards are available upon request.
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Document Outline FEATURES APPLICATIONS FUNCTIONAL BLOCK DIAGRAM GENERAL DESCRIPTION REVISION HISTORY SPECIFICATIONS ABSOLUTE MAXIMUM RATINGS ESD CAUTION PIN CONFIGURATION AND FUNCTION DESCRIPTIONS TYPICAL PERFORMANCE CHARACTERISTICS CIRCUIT DESCRIPTION INPUT ATTENUATOR AND INTERPOLATOR FIXED-GAIN STAGE AND OUTPUT BUFFER OUTPUT OFFSET CORRECTION INPUT AND OUTPUT IMPEDANCES GAIN CONTROL INTERFACE APPLICATIONS INFORMATION VGA OPERATION AGC OPERATION STABILITY AND LAYOUT CONSIDERATIONS EVALUATION BOARD OUTLINE DIMENSIONS ORDERING GUIDE