xDSL multistandard driver circuit
View Patent ↗An electric circuit for amplifying an xDSL signal comprises an operational amplifier and a signal monitoring circuit. The operational amplifier is configured to amplify the xDSL signal, is powered by a variable voltage supply and has a gain which is adjustable by an operating mode control signal. The signal monitoring circuit is activated by the operating mode control signal and is configured, when activated by the operating mode control signal, to generate a control signal to adjust the voltage of the variable voltage supply in order to adjust the maximal signal swing of the output signal of said operational amplifier. The control signal is generated by comparing the amplitude of the xDSL signal applied to the electric circuit with an amplitude threshold value.
1. An xDSL multistandard driver circuit for amplifying an xDSL signal which is applied to an input of said xDSL multistandard driver circuit; said xDSL multistandard driver circuit being configured to be adjusted to different xDSL settings of different xDSL standards according to an operating mode control signal and comprising:
an operational amplifier configured to amplify said xDSL signal applied to said xDSL multistandard driver circuit; said operational amplifier being powered by a variable voltage supply and having a gain being adjustable by said operating mode control signal;
a signal monitoring circuit which is activated by said operating mode control signal; said signal monitoring circuit being configured, when activated by said operating mode control signal, to generate a control signal to adjust the voltage of said variable voltage supply in order to adjust a maximal signal swing of the output signal of said operational amplifier; said control signal being generated by comparing an amplitude of said xDSL signal applied to said xDSL multistandard driver circuit with an amplitude threshold value: and
a first resistor, a second resistor and a first switching device which is controlled by said operating mode control signal; said switching device being configured to connect the first resistor or the second resistor between the output and the input of said operational amplifier dependent on said operating mode control signal to adjust said gain of said operational amplifier.
2. The circuit of claim 1 , wherein said control signal adjusts the voltage of said variable voltage supply to a higher voltage value, if said amplitude of said xDSL signal applied to said xDSL multistandard driver circuit exceeds the amplitude threshold value.
3. The circuit of claim 1 , wherein said monitoring circuit comprises a comparator.
4. The circuit of claim 1 , wherein said input of said xDSL multistandard driver circuit is connected via at least one first capacitor to an input of said signal monitoring circuit.
5. The circuit of claim 4 , wherein said xDSL multistandard driver circuit comprises a third resistor being connected between said first capacitor and said input of said operational amplifier.
6. The circuit of claim, wherein said amplitude threshold value is adjustable.
7. The circuit of claim 1 , wherein said xDSL multistandard driver circuit comprises a fourth resistor being connected to an output of said operational amplifier and to primary windings of a transformer.
8. The circuit of claim 7 , wherein said transformer has secondary windings which are connected in series with a second capacitor.
9. The circuit of claim 8 , wherein said second capacitor is connected to a signal output of said xDSL multistandard driver circuit.
10. The circuit of claim 1 , wherein said xDSL multistandard driver circuit comprises a second switching device being controlled by said control signal to adjust the voltage of said variable voltage supply.
11. The circuit of claim 1 , wherein resistances of the first resistor and the second resistor are programmable.
12. The circuit of claim 7 , wherein said fourth resistor is fed back to said input of said operational amplifier via a fifth resistor in order to produce a synthesized output impedance.
13. The circuit of claim 1 , wherein said operational amplifier is a class G power amplifier.
14. The circuit of claim 1 , wherein said xDSL multistandard driver circuit is of fully differential design.
15. The circuit of claim 1 , further comprising a control circuit which generates said operating mode control signal; said control circuit being configured to determine the appropriate xDSL of said applied xDSL signal based on a training signal sequence.
16. The circuit of claim 1 , wherein said xDSL settings are at least two out of the group of xDSL settings consisting of an ADSL, a VDSL, a SHDSL, and an HDSL standard setting.