ADSL Receiver Has Programmable Gain

A 70-MHz amplifier for asymmetrical digital subscriber line (ADSL) receiver equipment is available in the THS7002, which has programmable gain for central office or remote terminal applications. The IC includes a low-noise, voltage-feedback preamplifier and a programmable-gain amplifier. In addition, the preamplifier has a voltage noise of 2 nV/rtHz for maximum signal-to-noise ratio of the incoming signal. The preamp's output pin is accessible to allow easy addition of external filters if the design requires them. The programmable-gain amplifier is digitally controlled and provides gain/attenuation control from 20 to -22 dB in 6-dB steps. This step size and range enables the device to address the impedance variations in telephone wiring caused by varying line lengths and other conditions found in ADSL systems for high-speed Internet access.