LMH2832 - Fully-Differential, Dual, 1.1 GHz Digital Variable Gain Amplifier

The LMH2832 is a high-linearity, dual-channel, digital variable-gain amplifier (DVGA) for high-speed signal chain and data-acquisition systems. The LMH2832 is optimized to provide high bandwidth, low distortion, and low noise, thus making the device ideally suited as a dual, 14-bit, analog-to-digital converter (ADC) driver. The device consists of one fixed-gain block and one variable attenuator consisting of a total gain of 30 dB with a maximum attenuation of 39 dB. The gain range is from 30 dB to –9 dB in 1-dB gain steps with a gain accuracy of ±0.2 dB. The input impedance can be easily matched to 50-Ω or 75-Ω systems using a 1:3-Ω or 1:2-Ω ratio balun, respectively. The LMH2832 is designed to drive general-purpose ADCs and also meets the requirements for both data over cable service interface specification (DOCSIS) 3.0 32 quadrature amplitude modulation (QAM) carriers and DOCSIS 3.1 wideband orthogonal frequency-division multiplexing (OFDM) systems. With excellent NF (6.5 dB) and linearity, the LMH2832 is designed to perform to within DOCSIS specifications. The quiescent current in the power-down state is less than 5 mA per channel with the typical current consumption during operation at 105 mA per channel.

• Dual-Channel, Individual SPI™-Controlled DVGA
• Single 5-V Supply
• –3-dB Bandwidth: 1.1 GHz (Max Gain)
• Flat Bandwidth Response: 300 MHz
• Channel-to-Channel Gain Matching: ±0.05 dB
• Channel-to-Channel Phase Matching: ±0.1°
• Gain:
  • 30 dB to –9 dB
  • 1-dB Steps ±0.2 dB
• Output Third-Order Intercept Point (OIP3):
  • 43 dBm at 300 MHz
  • 51 dBm at 200 MHz
• Noise Figure (NF):
  • 6.5 dB (Max Gain) at 300 MHz, Z_IN = 150 Ω
• Adjustable Power Consumption:
  • 90 mA to 108 mA per Channel
• Power-Saving, Power-Down Feature:
  • I_Q < 4.5 mA per Channel
  • Power-Down Pin and SPI Programmability
• Input Return Loss at 300 MHz:
  • 17 dB (R_S = 150 Ω)