A power management unit integrated ADSL/ADSL2+ CPE analog front-end with −93.5dB THD for DMT-based applications

This paper presents a high linear analog front-end (AFE) for ADSL/ADSL2+ system applications. This AFE has the overall linearity of −93.5dB to ensure the ADSL/ADSL2+ modem to achieve up to 27.2Mbps down-stream data-rate on short loops. The AFE is implemented in two chips using 0.11um/55nm CMOS process with integrated power management unit (PMU) to optimize the data-rate, die area and power efficiency. The choice of the process is a compromise between the size of the digital circuits, and the analog performance and cost. Furthermore, a 90dB dynamic range (DR) CTSDM ADC is employed to relax the requirement of the front-end filters of the receiver, and thus the filter orders are reduced as well as the area and power consumption. The transmit path can achieve 90dB SNR and −95.2dB THD. The receive path can achieve 82.1dB SNR and −93.5dB THD. The AFE including line driver using the dual-chip solution dissipates 590 mW from 3.3V/5 V supply.