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.