Line driver circuit and method
A driver circuit for driving a transmission line includes a voltage driver and a current driver. The voltage driver is for driving the transmission line with a first voltage gain in a first operation mode. The current driver is activatable in a second operation mode for driving, together with the voltage driver, the transmission line with a second voltage gain. The transmission line may be an Ethernet-over-copper transmission line with electrical data signals from a data generator.
1. A driver circuit for driving a transmission line with electrical data signals from a data generator, the driver circuit comprising:
a voltage driver configured to drive the transmission line with a first voltage gain in a first operation mode; and
a current driver activatable in a second operation mode to drive, together with said voltage driver, the transmission line with a second voltage gain, wherein said current driver comprises at least one power stage and at least one amplifier configured to drive said at least one power stage.
2. The driver circuit of claim 1 , wherein said voltage driver comprises at least one power stage, and at least one amplifier configured to drive said at least one power stage.
3. The driver circuit of claim 1 , wherein said voltage driver comprises at least one output resistor configured to be coupled with said transmission line; and said current driver comprises:
a first stage configured to generate a replica of the electrical data signals from the data generator; and
a second stage configured to mirror current flowing in said first stage into a drive current for the transmission line with a mirror ratio, thereby reducing the voltage drop across said at least one output resistor.
4. The driver circuit of claim 3 , wherein said voltage driver and said current driver have a differential layout with differential inputs for the electrical data signals from the data generator and differential outputs to drive the transmission line.
5. The driver circuit of claim 4 , wherein said first stage comprises:
complementary portions configured to generate a replica of the electrical data signals on said differential inputs; and
a coupling resistor between said complementary portions whereby the mirror ratio is a function of the resistance value of said coupling resistor.
6. The driver circuit of claim 5 , wherein said coupling resistor has a resistance value given by a product of the mirror ratio and an impedance value of the transmission line.
7. The driver circuit of claim 1 , further comprising at least one switch activatable in the second operation mode to feed the electrical data signals to said current driver.
8. The driver circuit of claim 1 , wherein the transmission line is an Ethernet-over-copper transmission line.
9. A driver circuit for driving a transmission line with electrical data signals from a data generator, the driver circuit comprising:
a voltage driver comprising at least one output resistor coupled with the transmission line and configured to drive the transmission line with a first voltage gain in a first operation mode; and
a current driver activatable in a second operation mode to drive, together with said voltage driver, the transmission line with a second voltage gain, said current driver comprising
a first stage configured to generate a replica of the electrical data signals from the data generator, and
a second stage configured to mirror current flowing in said first stage into a drive current for the transmission line with a mirror ratio so as to reduce the voltage drop across said at least one output resistor.
10. The driver circuit of claim 9 , wherein said voltage driver comprises at least one power stage, and at least one amplifier configured to drive said at least one power stage; and wherein said current driver comprises at least one power stage, and at least one amplifier configured to drive said at least one power stage.
11. The driver circuit of claim 9 , further comprising at least one switch activatable in the second operation mode to feed the electrical data signals to said current driver.
12. The driver circuit of claim 9 , wherein said voltage driver and said current driver have a differential layout with differential inputs for the electrical data signals from the data generator and differential outputs to drive the transmission line.
13. The driver circuit of claim 12 , wherein said first stage comprises:
complementary portions configured to generate a replica of the electrical data signals on said differential inputs; and
a coupling resistor between said complementary portions whereby the mirror ratio is a function of the resistance value of said coupling resistor.
14. A method of driving a transmission line with electrical data signals from a data generator, the method comprising:
in a first operation mode, driving the transmission line with a first voltage gain using a voltage driver; and
in a second operation mode, driving the transmission line with a second voltage gain using a current driver activated together with the voltage driver, wherein the voltage driver comprises at least one power stage, and at least one amplifier configured to drive the at least one power stage; and wherein the current driver comprises at least one power stage, and at least one amplifier configured to drive the at least one power stage.
15. The method of claim 14 , wherein the voltage driver comprises at least one output resistor for coupling with the transmission line; and the current driver comprises:
a first stage configured to generate a replica of the electrical data signals from the data generator; and
a second stage configured to mirror current flowing in the first stage into a drive current for the transmission line with a mirror ratio, thereby reducing the voltage drop across the at least one output resistor.
16. The method of claim 15 , wherein the voltage driver and the current driver have a differential layout with differential inputs for the electrical data signals from the data generator and differential outputs to drive the transmission line.
17. The method of claim 16 , wherein the first stage comprises:
complementary portions configured to generate a replica of the electrical data signals on the differential inputs; and
a coupling resistor between the complementary portions whereby the mirror ratio is a function of the resistance value of the coupling resistor.
18. The method of claim 14 , further comprising at least one switch activatable in the second operation mode to feed the electrical data signals to the current driver.
19. The method of claim 14 , wherein the transmission line is an Ethernet-over-copper transmission line.