An Adaptive Maintain Power Signature (MPS) Scheme With Reusable Current Generator for Powered Device (PD)

The power over Ethernet (PoE) technology has gained intensive attention in networking market owing to the advantages of compactness, flexibility, and cost in application. The automatic maintain power signature (MPS) function specified by IEEE standard extracts the periodic pulsed current to enable applications requiring low power modes. However, a large driving capacity is required due to a large MPS current above 10 mA, sacrificing a certain area. This brief proposes an adaptive MPS scheme, which reuses existing class regulator and delay timer to source a pulsed MPS current to meet the MPS requirements, saving an area of 0.0104 mm2. The proposed MPS scheme has been fabricated in 0.18- $\mu $ m 120-V BCD process and the area is $1.37\times 1.00$ mm2. The experimental results show that the proposed PoE interface draws a pulsed current with a period of 312 ms and 25.6% duty cycle to address the issue of MPS absence in very low-power standby modes.