电流源与电压源驱动络变压器.pdf

电流源与电压源驱动网络变压器 Current and Voltage Source drive transformer Content 1. Current and Voltage Source drive 2. Bob Smith Termination 3. The function and classification of transform 4. Integrated and discrete magnetic 5. 8-Core and 12-Core Magnetic 6. CMC(common-mode choke) on the cable and PHY side 2 1 Current and Voltage Source drive The drive type of PHY contains voltage and current source drive. The center tap should connect to cap when use voltage source drive. Meanwhile the center tap should connect to power when use current source drive. But which kind of drive type to be used is determined by the PHY-ic . 3 Current Source Drive Center tap to power: Provide the needed drive current 4 Voltage Source Drive Center tap Cap: Provide low impedance path for common-mode current 5 Comparison of Power Consumption 6 Current Source power consumption To drive 1V output voltage and 10mA output current, PHY have to sink 40mA, 10mA going down and 30mA going down, current from the center tap. Finally the transformer have 20mA going down in N/2 turns of coil, so 20mA is wasted The total power consumption of 4 pairs differential in current mode driver. 40 mA/ch * 4 ch *1.8 V=288mW/port to drive +1V on all 4 pairs. 7 8 Voltage Source Power consumption To drive 1V output voltage and 10mA output c