System and circuit for a multi-channel optoelectronic device driver
View Patent ↗Disclosed is a system and circuit for a multi-channel optoelectronic device driver. The system and circuit include a differential buffer amplifier, an output driver amplifier, a dedicated voltage regulator, a load compensation circuit, a wave shaping circuit and a laser fault detection circuit. In a multi-channel configuration, each channel has a dedicated voltage regulator such that each channel provides a channel-specific drive signal.
1. A system for driving an optoelectronic device, comprising:
a buffer circuit for receiving a differential electrical signal;
a dedicated voltage regulator having an input adapted to receive a control signal and an output adapted to provide an output voltage that is a function of the control signal; and
a driver amplifier comprising a first amplifier having first and second differentially connected transistors and a first current source, a second amplifier having third and fourth differentially connected transistors and a second current source; a time delay network connected between the inputs of said first and second amplifiers and having a first input coupled to the output of said buffer circuit and a second input coupled to said voltage regulator and an output for providing a precisely controlled waveform to an optoelectronic device;
wherein a first input is coupled to the base of the first and third transistors and a second input is coupled to the base of the second and fourth transistors.
2. A system as in claim 1 , wherein said buffer circuit comprises:
an attenuating input stage having a pair of resistors; and
an amplifying output stage.
3. A system as in claim 1 , wherein said buffer circuit comprises:
an attenuating input stage having a pair of resistors; and
an amplifying output stage; and
said driver amplifier comprises:
first and second amplifying transistors adapted to receive a differential input at their respective base regions; and
first and second load resistors connected between the respective collector regions of said first and second transistors and the dedicated voltage regulator;
a common connection of the collector region of said second transistor and said second load resistor adapted to provide an output to an optoelectronic device.
4. A system as in claim 1 , further comprising:
a laser diode.
5. A system as in claim 4 , wherein said laser diode is a VCSEL.
6. A system as in claim 1 further comprising:
an additional buffer circuit for receiving a differential electrical signal;
an additional dedicated voltage regulator having an input adapted to receive a control signal and an output adapted to provide an output voltage that is a function of the control signal; and
an additional driver amplifier having a first input coupled to the output of said additional buffer circuit and a second input coupled to said additional voltage regulator and an output for providing a precisely controlled waveform to an additional optoelectronic device.
7. A system as in claim 6 , wherein said optoelectronic device and said additional optoelectronic device are light emitting diodes formed as an integrated array.
8. A system as in claim 7 , wherein said integrated array comprises:
VCSEL's.
9. A system as in claim 7 wherein said light emitting diodes have their cathodes connected in common and to ground.
10. A system as in claim 1 wherein the collector of the first transistor is connected to the collector of the fourth transistor and the collector of the second transistor is connected to the collector of the third transistor.
11. A system for driving an optoelectronic device, comprising:
a buffer circuit for receiving a differential electrical signal;
a dedicated voltage regulator having an input adapted to receive a control signal and an output adapted to provide an output voltage that is a function of the control signal; and
a driver amplifier comprising first and second amplifying transistors adapted to receive a differential input at their respective base regions, the emitters of said first and second transistors being connected to form a common node; first and second load resistors connected between the respective collector regions of said first and second transistors and the dedicated voltage regulator; a common connection of the collector region of said second transistor and said second load resistor adapted to provide an output to an optoelectronic device; a third transistor connected between said common node and ground; said dedicated voltage regulator has an output transistor; a fourth transistor connected to said output transistor forming a first current mirror; and a fifth transistor connected to said third transistor forming a second current mirror;
said driver amplifier having a first input coupled to the output of said buffer circuit and a second input coupled to said voltage regulator and an output for providing a precisely controlled waveform to an optoelectronic device.
12. A system as in claim 11 , further comprising:
sixth and seventh transistors forming a third current mirror; and
a third resistor connected to said seventh transistor.
13. A system as in claim 12 , further comprising:
a comparator connected to the common connection of said third resistor and said seventh transistor.