Laser driver and optical transmitter implementing the same
An LD-Driver with the push-pull arrangement is disclosed. The driver includes the high side driver driven by the positive phase signal and the low side driver driven by the negative phase signal. When the positive phase signal is in HIGH, the high side driver becomes ON and the LD driver provides additional current to the bias current for the LD; while, when the negative phase signal is in HIGH, the low side driver becomes ON and the LD driver extracts a portion of the bias current for the LD.
1. A laser diode driver to drive a semiconductor laser diode, the driver being driven with a positive phase signal and a negative phase signal complementary to each other, comprising:
a high side driver including a series circuit of a first MOSFET and a second MOSFET, the first MOSFET having a conducting type different from a conducting type of the second MOSFET, the first MOSFET being driven by the positive phase signal, the high side driver providing a positive current to the semiconductor laser diode when the positive phase signal is in HIGH; and
a low side driver driven by the negative phase signal, the low side driver extracting a negative current from the semiconductor laser diode.
2. The laser diode driver of claim 1 , wherein
the second MOSFET is fixedly biased.
3. The laser diode driver of claim 1 , wherein
the second MOSFET is driven by the negative phase signal.
4. The laser diode driver of claim 1 , wherein
the low side driver includes a third MOSFET driven by the negative phase signal.
5. The laser diode driver of claim 4 , wherein
the low side driver further includes an emitter follower to receive the negative phase signal, and wherein
the third MOSFET is coupled with the emitter follower in DC mode.
6. The laser diode driver of claim 1 , wherein
the low side driver includes a bipolar transistor driven by the negative phase signal.
7. The laser diode driver of claim 6 , wherein
the low side driver includes an emitter follower to receive the negative phase signal, and wherein
the bipolar transistor is coupled with the emitter follower in DC mode.
8. An optical transmitter, comprising:
a semiconductor laser diode;
a bias current source to provide a bias current to the laser diode;
a driver driven by a positive phase signal and a negative phase signal complementary to each other, the driver including,
a high side driver including a series circuit of a first MOSFET and a second MOSFET, the first MOSFET having a conducting type different from a conducting type of the second MOSFET, the first MOSFET being driven by the positive phase signal to add a positive current to the bias current when the positive signal is in HIGH, and
a low side driver driven by the negative phase signal to extract a negative current from the bias current when the negative signal is in HIGH.
9. The optical transmitter of claim 8 , wherein
the second MOSFET is fixedly biased.
10. The optical transmitter of claim 8 , wherein
the second MOSFET is driven by the negative phase signal.
11. The optical transmitter of claim 8 , wherein
the low side driver includes a third MOSFET driven by the negative phase signal.
12. The optical transmitter of claim 11 , wherein
the low side driver further includes an emitter follower to receive the negative phase signal, the third MOSFET being coupled with the emitter follower in DC mode.
13. The laser diode driver of claim 8 , wherein
the low side driver includes a bipolar transistor driven by the negative phase signal.
14. The laser diode driver of claim 13 wherein
the low side driver includes an emitter follower to receive the negative phase signal, the bipolar transistor being coupled with the emitter follower in DC mode.