The AD8322 is a low-cost, digitally controlled variable gain amplifier optimized for coaxial line driving applications such as cable modems that are designed to the MCNS-DOCSIS upstream standard. An 8-bit serial word determines the desired output gain over a 42.14 dB range, with gain steps of 6.02 dB/major carry.
The AD8322 comprises a digitally controlled variable attenuator of 0 dB to 42.14 dB, which is preceded by a low-noise, fixed-gain buffer and is followed by a low-distortion, high-power amplifier. The AD8322 accepts a differential or single-ended input signal. The output is specified for driving a 75 Ω load, such as coaxial cable.
Distortion performance of 58 dBc is achieved with an output level up to 60 dBmV at 21 MHz bandwidth. A key performance and cost advantage of the AD8322 results from the ability to maintain a constant 75 Ω output impedance during power-up and powerdown conditions. This eliminates the need for external 75 Ω termination resulting in twice the effective output voltage when compared to a standard operational amplifier.
The AD8322 is packaged in a low-cost 28-lead TSSOP, operates from a single 5 V supply, and has an operational temperature range of 40°C to +85°C.
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Gain Programmable Line Driver DOCSIS-Compliant Data Modems Interactive Set-Top Boxes PC Plug-in ModemsGeneral-Purpose Digitally Controlled Variable Gain Block
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Supports DOCSIS Standard for Reverse Path Transmission Gain Programmable in 6 dB Steps Over a 42 dB Range Low Distortion at 60 dBmV Output 58 dBc SFDR at 21 MHz 56 dBc SFDR at 42 MHz Output Noise Level 46 dBmV in 160 kHz Bandwidth Maintains 75 Output Impedance Power-Up and Power-Down Condition 180 MHz Bandwidth 5 V Supply Operation Supports SPI Interfaces
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Supply Voltage +VS
Pins 6, 8, 9, 20, 21, 23, 27 . . . . . . . . . . . . . . . . . . . . . . 6 V
Input Voltages
Pins 25, 26 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±0.5 V
Pins 1, 2, 3, 7 . . . . . . . . . . . . . . . . . . . . . . 0.8 V to +5.5 V
Internal Power Dissipation
TSSOP (RU) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.90 W
Operating Temperature Range . . . . . . . . . . . 40°C to +85°C
Storage Temperature Range . . . . . . . . . . .. 65°C to +150°C
Lead Temperature, Soldering 60 seconds . . . . . . . . . . 300°C
Post a Buying Lead
Required Field 
