Features: Supports DOCSIS Standard for Reverse Path
Transmission
Gain Programmable in 6.02 dB Steps over a 48.16 dB
Range
Low Distortion at 60 dBmV Output
63 dBc SFDR at 21 MHz
57 dBc SFDR at 42 MHz
Output Noise Level
47 dBmV in 160 kHz
Maintains 75 Output Impedance
-Transmit Enable and Transmit Disable Modes
Upper Bandwidth: 160 MHz (Full Gain Range)
5 V Supply Operation
Supports SPI Interfaces
Application-Gain-Programmable Line Driver
-DOCSIS High-Speed Data Modems
-Interactive Cable Set-Top Boxes
-PC Plug-in Cable Modems
-General-Purpose Digitally Controlled Variable Gain BlockPinout
Specifications
| Gain Control |
Digital |
| -3 dB BW (MHz) |
160MHz |
| Gain Low End (dB) |
-18dB |
| Gain High End (dB) |
+30dB |
| Number of Channels |
1 |
| Spectral Noise (nV/rtHz) |
64nV/rtHz |
| Supply Voltage (V) |
+5V |
| Supply Current |
105mA |
| Gain Accuracy (dB) |
±1dB |
Supply Voltage +VS
Pins 4, 6, 11, 12, 16 . . . . . . . . . . . . . . . . . . . . . . .. . . . . . 6 V
Input Voltages
Pins 17, 18 . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . ±0.5 V
Pins 1, 2, 3, 19, 20 . . . . . . . . . . . . . . . . . . . 0.8 V to +5.5 V
Internal Power Dissipation
TSSOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ........ . . . 810mW
Operating Temperature Range . . . . . . . . ..40°C to +85°C
Storage Temperature Range . . . . . . . . . .65°C to +150°C
Lead Temperature, Soldering 60 seconds . . . . . . . . . 300°CDescriptionThe AD8327 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 48.16 dB range resulting in gain changes of 6.02 dB/major carry.
The AD8327 comprises a digitally controlled variable attenuator of 0 dB to 48.16 dB, which is preceded by a low noise, fixed gain buffer and followed by a low distortion, high power amplifier. The AD8327 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 63 dBc is achieved with an output level up to 60dBmV at 21MHz bandwidth. A key performance and cost advantage of the AD8327 results from the ability to maintain a constant 75Ωoutput impedance during Transmit Enable and Transmit Disable conditions. In addition, this device has a sleep mode function that reduces the quiescent current to 5mA.
The AD8327 is packaged in a low-cost 20-lead TSSOP, operates from a single 5 V supply, and has an operational temperature range of 40°C to +85°C.
AD8327 Data Sheet
