A Low Voltage Low Power Adaptive Transceiver for Twisted-Pair Cable Communication

Twisted-pair based data communication protocols, such as the mature low voltage differential signal (LVDS) and RS485 protocols have been widely adapted for a general purpose. The drive strength is kept at a fixed value once the system is designed. For some application specific use cases, that require low power consumption, these protocols do not meet the requirements. This paper presents a novel method to reduce the power consumption in twisted-pair communication. Unlike the traditional current mode logic (CML) circuits, a new method uses an adjustable current source to drive the circuits. The current is controlled by a digital analog convertor (DAC) of a micro control unit (MCU). By monitoring the bit error rate (BER) of the transmission line, transceivers adaptively optimize the driver current to meet the specific criteria for the transmission line with the lowest power possible. Comparing with the fixed drive strength mode, the adaptive mode transceiver reduces 32.3% power consumption. Together with some low voltage technologies, the transceiver consumes only 2.3% of the current used in traditional LVDS driver on a 14 meter twisted-pair cable at a data rate is about 4 Mbps.