DVGA for high-speed signal chain and data-acquisition systems

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