The AD8322 is a low-cost, digitally controlled variable gain amplifier. It supports the DOCSIS standard for reverse path transmission, and the gain can be programmed in 6 dB steps over a 42 dB range. At 60 dBmV output, the distortion is low, -58 dBc SFDR at 21 MHz and -56 dBc SFDR at 42 MHz. The output noise level is -46 dBmV, with a bandwidth of 160 kHz. It supports SPI interfaces. It can be used for gain programmable line drivers, DOCSIS-compliant data modems, interactive set-top boxes, PC plug-in modems, and general-purpose digitally controlled variable gain blocks.
The AD8322 is a low‑cost, digitally controlled variable‑gain line driver optimized for coaxial cable‑driving applications such as DOCSIS upstream modems. It provides a programmable gain range of about 42 dB in 6 dB steps, maintains a constant 75 Ω output impedance, and delivers up to 60 dBmV output power.
The device operates from a single 5 V supply, supports an SPI programming interface, and includes built‑in ESD protection. It is supplied in a 28‑lead TSSOP package and is rated for –40 °C to +85 °C operation.
| Supply Voltage | 5 V (4.75‑5.25 V operating range) |
|---|---|
| Gain Range | 41.0 dB – 43.2 dB |
| Gain Step | 6.02 dB per major carry |
| Bandwidth (-3 dB) | 180 MHz (all gain codes) |
| Input Resistance (Single‑Ended) | 210 Ω |
| Input Resistance (Differential) | 235 Ω |
| Output Noise (Min Gain, 10 MHz) | -46 dBmV in 160 kHz BW |
| Quiescent Current (Power‑Up) | 100 mA – 126 mA |
| Quiescent Current (Power‑Down) | 44 mA – 60 mA |
| Operating Temperature Range | -40 °C to +85 °C |
The AD8322 provides a programmable gain range from 41.0 dB to 43.2 dB.
Gain is programmed via an 8‑bit SPI interface using the DATEN, SDATA, and CLK pins.
The device operates from a single 5 V supply, with an acceptable range of 4.75 V to 5.25 V.