AD8320

Features:

8-Bit Serial Gain Control
V/V/LSB Linear Gain Response
36 dB Gain Range
±0.20 dB Gain Accuracy
Upper Bandwidth: 150 MHz
22 dBm 1 dB Compression Point (75 )
Drives Low Distortion Signals into 75 Load:
57 dBc SFDR at 42 MHz and 12 dBm Out
46 dBc SFDR at 42 MHz and 18 dBm Out
Single Supply Operation from 5 V to 12 V
Maintains 75 Output Impedance
Power-Up and Power-Down Condition
Supports SPI Input Control Standard




Application

Coaxial Cable Driver
HFC Cable Telephony Systems
HFC High Speed Data Modems
Interactive Set-Top Boxes
PC Plug-In Modems
Interfaces with AD9853 I2C Controlled Digital Modulator
High Performance Digitally Controlled Variable Gain
Block




Pinout








Specifications



Supply Voltage +VS
Pins 7, 8, 9, 17, 20 . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .0.8 V to +13 V
Input Voltages
Pins 19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .±3 V
Pins 1, 2, 3, 6 . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . . 0.8 V to +5 V
Internal Power Dissipation
Small Outline (RP) . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . . .. .1.3 W
Operating Temperature Range . . . . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . 40°C to +85°C
Storage Temperature Range . . . . . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . 65°C to +150°C
Lead Temperature, Soldering 60 seconds . . . . . . . . . .. . . . . . . .. . . . . . . .. . . . . . +300°C




Description

The AD8320 is a digitally controlled variable gain amplifier optimized for coaxial line driving applications. An 8-bit serial word determines the desired output gain over a 36 dB range (256 gain levels). The AD8320 provides linear gain response.

The AD8320 is made up of a digitally controlled variable attenuatorof 0 dB to 36 dB, which is preceded by a low noise, fixed gain buffer and followed by a low distortion high power amplifier. The AD8320 has a 220 input impedance and accepts a single-ended input signal with a specified analog input level of up to 0.310 V p-p. The output is specified for driving a 75 load, such as coaxial cable, although the AD8320 is capable of driving other loads. Distortion performance of 57 dBc is achieved with an output level up to 12 dBm (3.1 V p-p) at 42 MHz, while 46 dBc distortion is achieved with an output level up to 18 dBm (6.2 V p-p).

A key performance and cost advantage of the AD8320 results from the ability to maintain a constant 75 output impedance during power-up and power-down conditions. This eliminates the need for external 75 back-termination, resulting in twice the effective output voltage when compared to a standard operational amplifier. Additionally, the on-chip 75 termination results in low glitch output during power-down and power-up transitions, eliminating the need for an external switch.

The AD8320 is packaged in a 20-lead SOIC and operates from a single +5 V through +12 V supply and has an operational temperature range of 40°C to +85°C.