A high linearity voltage-current converter able to compensate for mobility degradation comprises a first constant current source circuit, a first current mirror unit, a second constant current source circuit, a second current mirror unit, a seventh MOS transistor and an eighth MOS transistor. The delay measurement subsystem is connected to a call originating handset to play an acoustic test signal to the transmitter of the originating handset. The throughput may be further increased by performing a slurry impregnation treatment before or after the PIP treatment, in which slurried SiC is impregnated into the voids in the matrix layer. The multimode optical fiber exhibits reduced bending losses. Based on a determination that the prediction matches the actual outcome, the training may stop. Carbon nanotube arrays are combined with a thermally conductive metal filler disposed between the nanotubes.