Class AB differential line drivers
View Patent ↗An output stage of a differential line driver generates a differential output signal. A common-mode component of the differential output signal is decoupled from the differential output signal using a common-mode voltage sense. The common-mode component of the differential output signal is provided to a capacitor that is coupled between the output stage and the common-mode voltage sense.
1. An apparatus, comprising:
a first input stage configured to generate a first signal responsive to a first differential input signal;
a second input stage configured to generate a second signal responsive to a second differential input signal;
a first output stage configured to generate a first differential output signal responsive to the first signal generated by the first input stage;
a second output stage configured to generate a second differential output signal responsive to the second signal generated by the second input stage; and
a common-mode voltage sense configured to decouple a common-mode component of the first and second differential output signals.
2. The apparatus of claim 1 , further comprising:
a capacitor coupled to the common-mode voltage sense, the first input stage, and the first output stage.
3. The apparatus of claim 1 , further comprising:
a capacitor coupled to the second input stage, the second output stage, and the common-mode voltage sense.
4. The apparatus of claim 1 , further comprising:
a first capacitor coupled to a first output of the common-mode voltage sense, an output of the first input stage, and an input of the first output stage; and
a second capacitor coupled to the first output of the common-mode voltage sense, an output of the second input stage, and an input of the second output stage.
5. An apparatus, further comprising:
an input stage configured to generate a signal responsive to a differential input signal;
an output stage configured to generate a differential output signal responsive to the signal generated by the input stage;
a first common mode voltage sense coupled to the output stage and configured to decouple a common-mode component of the differential output signal; and
a second common-mode voltage sense coupled to the input stage and configured to decouple a common-mode component of the differential input signal.
6. An apparatus, comprising:
an input stage configured to generate a signal responsive to a differential input signal;
an output stage configured to generate a differential output signal responsive to the signal generated by the input stage;
a common mode voltage sense configured to decouple a common-mode component of the differential output signal; and
a current source configured to generate a bias current for the input stage responsive to an output current generated by the output stage.
7. An apparatus, comprising:
an input stage configured to generate a signal responsive to a differential input signal;
an output stage configured to generate a differential output signal responsive to the signal generated by the input stage; and
a common mode voltage sense configured to decouple a common-mode component of the differential output signal, wherein
the input stage further comprises a first transconductance stage and a second transconductance stage, the first transconductance stage configured to generate at least a portion of the signal responsive to the differential output signal and the differential input signal, the second transconductance stage configured to generate at least a portion of the signal responsive to the common-mode component of the differential output signal.
8. The apparatus of claim 1 , further comprising:
a current source configured to generate a bias for the first input stage responsive to an output current generated by at least one of the first and second output stages.
9. The apparatus of claim 1 , further comprising:
a current source configured to generate a bias for the second input stage responsive to an output current generated by at least one of the first and second output stages.
10. The apparatus of claim 1 , wherein
the first input stage generates the first signal based on the first differential input signal and the first differential output signal received from an output of the first output stage.
11. The apparatus of claim 1 , wherein
the second input stage generates the second signal based on the second differential input signal and the second differential output signal received from an output of the second output stage.
12. The apparatus of claim 1 , wherein
the first input stage comprises a first transconductance stage and a second transconductance stage.
13. The apparatus of claim 12 , wherein
the first transconductance stage is configured to generate at least a portion of the first signal responsive to the first differential output signal and the first differential input signal, and
the second transconductance stage is configured to generate at least a portion of the first signal responsive to the common-mode component of the first differential output signal.
14. The apparatus of claim 1 , wherein
the second input stage comprises a first transconductance stage and a second transconductance stage.
15. The apparatus of claim 12 , wherein
the first transconductance stage is configured to generate at least a portion of the second signal responsive to the second differential output signal and the second differential input signal, and
the second transconductance stage is configured to generate at least a portion of the second signal responsive to the common-mode component of the second differential output signal.
16. The apparatus of claim 1 , further comprising:
a second common-mode voltage sense configured to decouple a common-mode component of the first and second differential output signals.
17. The apparatus of claim 5 , further comprising
a second input stage configured to generate a second signal responsive to a second differential input signal.
18. The apparatus of claim 17 , further comprising
a second output stage configured to generate a second differential output signal responsive to the second signal generated by the second input stage.
19. The apparatus of claim 5 , further comprising:
a capacitor coupled to the first common-mode voltage sense, the input stage, and the output stage.
20. The apparatus of claim 19 , wherein
the capacitor is coupled to a first output of the first common-mode voltage sense, an output of the input stage, and an input of the output stage.