LMH6401 - 4.5 GHz Ultra Wideband Digital Variable Gain Amplifier

The LMH6401 is a wideband, digitally-controlled, variable-gain amplifier (DVGA) designed for dc to radio frequency (RF), intermediate frequency (IF), and high-speed time-domain applications. The device is an ideal analog-to-digital converter (ADC) driver for dc- or ac-coupled applications that require an automatic gain control (AGC).

Noise and distortion performance is optimized to drive ultra-wideband ADCs. The amplifier has an 8-dB noise figure at maximum gain and a –63-dBc harmonic distortion at 1 GHz for full-scale signal levels. The device supports both single- and split-supply operation for driving an ADC. A common-mode reference input pin is provided to align the amplifier output common-mode with the ADC input requirements.

Gain control is performed via an SPI™ interface, allowing a 32-dB gain range from –6 dB to 26 dB in 1-dB steps. A power-down feature is also available through the external PD pin or SPI control.

This level of performance is achieved at a low power level of 345 mW. The operating ambient temperature range is –40°C to 85°C.

• 3-dB Bandwidth: 4.5 GHz at 26-dB Gain
• Gain Range: –6 dB to 26 dB in 1-dB Steps
• Differential Input Impedance: 100 Ω
• Differential Output with Common-Mode Control
• Distortion at Max Gain (V_O = 2 V_PPD, R_L = 200 Ω):
  • 200 MHz: HD2 at –73 dBc, HD3 at –80 dBc
  • 500 MHz: HD2 at –68 dBc, HD3 at –72 dBc
  • 1 GHz: HD2 at –63 dBc, HD3 at –63 dBc
  • 2 GHz: HD2 at –58 dBc, HD3 at –54 dBc
• Output IP3:
  • 43 dBm at 200 MHz
  • 33 dBm at 1 GHz
  • 27 dBm at 2 GHz
• Output IP2:
  • 67 dBm at 200 MHz
  • 60 dBm at 1 GHz
  • 52 dBm at 2 GHz
• 8-dB Noise Figure at 1 GHz, R_S = 100 Ω
• 82-ps Rise, Fall Time Pulse Response
• Supply Operation: 5.0 V at 69 mA
• Supports Single- and (±) Split-Supply Operation:
  • DC- and AC-Coupled Applications
• Fabricated on an Advanced Complementary BiCMOS Process
• 3-mm × 3-mm UQFN-16 Package