Temperature compensation circuits
View Patent ↗A differential driver configured to drive an optical source. The differential driver includes an anode transistor configured to connect to a diode anode. The differential driver further includes a cathode transistor configured to connect to a diode cathode. The differential driver additionally includes a tail current transistor. The tail current transistor controls the amount of modulation current through a diode. The tail current transistor includes provisions that control the current through the tail current transistor for controlling the amount of modulation current through the diode. The provisions are dependant on a temperature in or at which the diode operates.
1. A differential driver configured to drive an optical source, the differential driver comprising:
an anode transistor configured to capacitively couple to a diode anode;
a cathode transistor configured to capacitively couple to a diode cathode; and
a tail current transistor that controls the amount of modulation current through a diode;
a plurality of temperature compensating resistors adapted to control current through the tail current transistor, one or more of the temperature compensating resistors being selected for connection to the tail current transistor in dependence on a characteristics rating of the optical source.
2. A differential driver configured to drive an optical source, the differential driver comprising:
an anode transistor configured to couple to a diode anode;
a cathode transistor configured to couple to a diode cathode; and
a tail current transistor that controls the amount of modulation current through a diode, the tail current transistor comprising provisions that control the current through the tail current transistor for controlling the amount of modulation current through the diode, wherein the provisions are dependent on a temperature in or at which the diode operates,
wherein the provisions that control the current through the tail current transistor comprise a plurality of temperature compensating resistors connected in parallel and each including a fixed temperature coefficient, a first end of each of the temperature compensating resistors being directly coupled to the tail current transistor.
3. The differential driver of claim 2 , wherein a second end of each of the temperature compensating resistors is directly coupled to a bond pad that allows the temperature compensating resistors to be connected to a biasing power supply.
4. The differential driver as recited in claim 2 , wherein the temperature compensating resistors are temperature tunable.
5. An optical transmitter comprising:
an optical source comprising a diode having a cathode and an anode; and
a differential driver coupled to the optical source, the differential driver comprising:
an anode connected transistor capacitively coupled to the diode anode;
a cathode connected transistor capacitively coupled to the diode cathode; and
a tail current transistor that controls the amount of modulation current through the diode;
a plurality of temperature compensating resistors adapted to control current through the tail current transistor, one or more of the temperature compensating resistors being selected for connection to the tail current transistor in dependence on a characteristics rating of the optical source.
6. The optical transmitter of claim 5 , wherein the optical transmitter is packaged in a TO can.
7. The optical transmitter of claim 5 , wherein the optical transmitter is packaged in an overmolded leadframe.
8. The optical transmitter of claim 5 , further comprising a photodetector optically coupled to the optical source.
9. The optical transmitter of claim 8 , wherein the photodetector is a discrete component.
10. The optical transmitter of claim 8 , wherein the photodetector is formed epitaxially with the optical source.
11. An optical transmitter comprising:
an optical source comprising a diode having a cathode and an anode; and
a differential driver coupled to the optical source, the differential driver comprising:
an anode connected transistor coupled to the diode anode;
a cathode connected transistor coupled to the diode cathode; and
a tail current transistor that controls the amount of modulation current through the diode, the tail current transistor comprising provisions that control the current through the tail current transistor for controlling the amount of modulation current through the diode,
wherein the provisions that control the current through the tail current transistor comprise a plurality of temperature compensating resistors connected in parallel and each including a fixed temperature coefficient, a first end of each of the temperature compensating resistors being directly coupled to the tail current transistor.
12. The optical transmitter of claim 11 , wherein a second end of each of the temperature compensating resistors is directly coupled to a bond pad that allows the temperature compensating resistors to be connected to a biasing power supply.
13. The optical transmitter of claim 11 , wherein the optical transmitter is packaged in one of a TO can and an overmolded leadframe.
14. The optical transmitter of claim 11 , further comprising a photodetector optically coupled to the optical source.
15. The optical transmitter of claim 14 , wherein the photodetector is a discrete component.
16. The optical transmitter of claim 14 , wherein the photodetector is formed epitaxially with the optical source.
17. The optical transmitter as recited in claim 11 , wherein the temperature compensating resistors are temperature tunable.
18. The optical transmitter as recited in claim 11 , wherein a select combination of the temperature compensating resistors are coupled to a biasing power supply, the combination being selected so as to substantially match characteristics of the optical source.