ADI AD8368ACPZ-REEL7

The AD8368 is a variable gain amplifier (VGA) with analog linear-in-dB gain control, operating over a frequency range from low frequencies to 800 MHz. Employing ADI's X-AMP® architecture — an innovative technology that enables high-performance variable gain control — the device delivers excellent gain range, conformance, and flatness.

The gain range of −12 dB to +22 dB is precisely adjustable at 37.5 dB/V with minimal conformance error. The AD8368 has a nominal 3 dB bandwidth of 800 MHz, independent of gain setting. OIP3 is 33 dBm at 140 MHz at maximum gain. Output noise floor is −143 dBm/Hz, with a corresponding noise figure of 9.5 dB at maximum gain. Nominal single-ended input and output impedance is 50 Ω.

By pulling the MODE pin to the positive supply voltage or ground, the gain of the AD8368 can be set as an increasing or decreasing function of the gain control voltage, respectively. When the MODE pin is pulled high, the AD8368 operates as a typical VGA with increasing gain.

By grounding the MODE pin and using the on-chip rms detector, the AD8368 can be configured as a complete automatic gain control (AGC) system with RSSI. Output power is compared to an internal default setpoint of 63 mV rms (−11 dBm into 50 Ω). Because a dedicated detector input is available at DETI, the AGC loop can regulate the level at the AD8368 output or at any point in the signal chain over a maximum input power range of 34 dB. Additionally, the setpoint level can be raised by attenuating the output signal before applying it to the detector.

The AD8368 operates from a 4.5 V to 5.5 V supply and draws 60 mA. Pulling the ENBL pin to ground enables a full power-down state with current consumption below 3 mA. Fabricated using ADI's proprietary SiGe SOI complementary bipolar IC process, the AD8368 is available in a 24-lead LFCSP package and operates over a temperature range of −40°C to +85°C. An evaluation board is also available.

• Analog variable gain range: −12 dB to +22 dB
• Linear-in-dB scaling: 37.5 dB/V
• 3 dB bandwidth: 800 MHz (V_GAIN=0.5 V)
• Integrated RMS detector
• P1dB: 16 dBm (140 MHz)
• Output IP3: 33 dBm (140 MHz)
• Noise figure at maximum gain: 9.5 dB (140 MHz)
• Input and output impedance: 50 Ω
• Single supply: 4.5 V to 5.5 V
• RoHS compliant, 24-lead LFCSP package

• Complete IF AGC amplifier
• Gain adjustment and leveling
• Cellular base stations
• Point-to-point radio links
• RF instrumentation