Quad Low Noise, Low Cost Variable Gain Amplifier Data Sheet AD8335 FEATURES FUNCTIONAL BLOCK DIAGRAM Low noise preamplifier (PrA) Voltage noise = 1.3 nV/Hz typical Current noise = 2.4 pA/Hz typical VOH1 NF = 7 dB (R = R = 50 ) S IN PIP1 ATTEN 20dB VMD1 48dB TO TO 18dB Single-ended input V maximum = 625 mV p-p IN 28dB 0dB PMD1 VOL1 Active input match POP2 Input SNR (noise bandwidth = 20 MHz) = 92 dB PMD2 INTERPOLATOR GAIN INT VGN1 VGA VMD2 18dB PIP2 Differential output SL12 PON2 V maximum = 5 V p-p, R = 500 differential OUT L INTERPOLATOR GAIN INT VGN2 Gain range (8 dB output gain step) VCM2 VOL2 10 dB to +38 dBlow gain mode VIP2 ATTEN 20dB 48dB TO TO 2 dB to +46 dBhigh gain mode 28dB 0dB VIN2 VOH2 Accurate linear-in-dB gain control AD8335 VOH3 PrA + VGA performance VIN3 ATTEN 20dB 3 dB bandwidth of 85 MHz 48dB TO TO 28dB 0dB VIP3 Excellent overload performance VOL3 VCM3 Supply: 5 V PON3 Power consumption INTERPOLATOR GAIN INT VGN3 95 mW/channel (380 mW total) PIP3 18dB VMD3 SL34 65 mW/channel (PrA off 260 mW total) PMD3 INTERPOLATOR GAIN INT VGN4 Power-down POP3 VOL4 PMD4 ATTEN 20dB 18dB VMD4 48dB TO TO APPLICATIONS 28dB 0dB PIP4 VOH4 Medical imaging (ultrasound, gamma cameras) Sonar Test and measurement Precise, stable wideband gain control Figure 1. GENERAL DESCRIPTION The AD8335 is a quad variable gain amplifier (VGA) with Assuming a 20 MHz noise bandwidth (NBW), the Nyquist low noise preamplifier intended for cost and power sensitive frequency for a 40 MHz ADC, the input SNR is 92 dB. The applications. Each channel features a gain range of 48 dB, fully HLxx pin optimizes the output SNR for 10-bit and 12-bit differential signal paths, active input preamplifier matching, ADCs with 1 V p-p or 2 V p-p full-scale (FS) inputs. and user-selectable maximum gains of 46 dB and 38 dB. Channel 1 and Channel 2 are enabled through the EN12 pin, and Individual gain controls are provided for each channel. Channel 3 and Channel 4 are enabled through the EN34 pin. The preamplifier (PrA) has a single-ended to differential gain of For VGA only applications, the PrAs can be powered down, 8 (18.06 dB) and accepts input signals 625 mV p-p. PrA noise is significantly reducing power consumption. 1.2 nV/Hz and the combined input referred voltage noise of The AD8335 is available in a 64-lead lead frame chip scale the PrA and VGA is 1.3 nV/Hz at maximum gain. package (9 mm 9 mm) for the industrial temperature range of 40C to +85C. Rev. B 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 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 20042012 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. SP12 SP34 PON4 PON1 POP4 POP1 VIP1 VIP4 VCM1 VCM4 VIN4 VIN1 EN34 EN12 HL34 HL12 04976-001AD8335 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 VGA ............................................................................................. 18 Applications....................................................................................... 1 Applications Information .............................................................. 20 Functional Block Diagram .............................................................. 1 Ultrasound .................................................................................. 20 General Description ......................................................................... 1 Basic Connections...................................................................... 21 Revision History ............................................................................... 2 Preamp Connections ................................................................. 21 Specifications..................................................................................... 3 Input Overdrive .......................................................................... 22 Absolute Maximum Ratings............................................................ 5 Logic Inputs................................................................................. 22 ESD Caution.................................................................................. 5 Common-Mode Pins ................................................................. 22 Pin Configuration and Function Descriptions............................. 6 Driving ADCs............................................................................. 22 Typical Performance Characteristics ............................................. 7 Evaluation Board ............................................................................ 23 Test Circuits..................................................................................... 15 Board Layout............................................................................... 23 Theory of Operation ...................................................................... 16 Outline Dimensions....................................................................... 28 Enable Summary ........................................................................ 16 Ordering Guide .......................................................................... 28 Preamp ......................................................................................... 17 REVISION HISTORY 2/12Rev. A to Rev. B Changes to Figure 1.......................................................................... 1 Added Exposed Pad Notation to Figure 2 and Table 3................ 6 Changes to Figure 12 Caption....................................................... 11 Deleted Measurement Setup Section ........................................... 23 Changes to Figure 60 through Figure 68 ..................................... 23 Deleted Table 7................................................................................ 27 8/08Rev. 0 to Rev. A Changes to Features Section............................................................ 1 Changes to Table 1, Scale Factor Parameter.................................. 4 Changes to Theory of Operation Section.................................... 16 Changes to Figure 54...................................................................... 16 Changes to Equation 4 ................................................................... 18 Changes to Figure 58...................................................................... 21 Added Evaluation Board Section ................................................. 23 Added Figure 60 to Figure 68........................................................ 23 Updated Outline Dimensions ....................................................... 28 Changes to Ordering Guide .......................................................... 28 9/04Revision 0: Initial Version Rev. B Page 2 of 28