Integrated circuit for controlling a laser diode
View Patent ↗The invention relates to an integrated circuit for controlling a laser diode, comprising a signal input for receiving a data signal; a signal output for connection to the laser diode; a modulator for modulation of the data signal; a current infeed connected to the signal output for the supply of a bias current; a coupling capacitor between the output of the modulator and the signal output in order to form a high pass with the differential resistor of the laser diode. Preferably, the circuit also comprises an active compensation circuit with a low pass connected to the output of the modulator; and a circuit which is connected to the low pass for producing a signal which is inversely proportional to the low pass output voltage and which is added to the output signal or subtracted from the output signal. The low pass can be controlled by a circuit guiding the data signal.
1. An integrated circuit for controlling a laser diode, having:
a signal input for receiving a data signal;
a signal output for connection to the laser diode;
a modulator for modulation the data signal, wherein the modulator has a first node coupled to the signal input node such that the data signal is modulated by the modulator after being received by the signal input node;
a current infeed connected to the signal output node and serving for the supply of a bias current;
a coupling capacitor having a first terminal coupled to a second node of the modulator and a second terminal coupled to the signal output node, for forming a high-pass filter with the differential resistor of the laser diode connected to the signal output node, and
an active compensation circuit having:
a low-pass filter connected to the output of the modulator,
a voltage inverter connected to the low-pass filter and serving for inverting the voltage generated by the low-pass filter in accordance with the low-pass filter transfer function;
a voltage follower connected to the output of the voltage inverter; and
a converter between the output of the voltage follower and the signal output, for generating a current which is inversely proportional to the low-pass filter output voltage.
2. The integrated circuit as claimed in claim 1 , the low-pass filter being controlled by a circuit carrying the data signal.
3. An integrated circuit for controlling a laser diode, having:
a signal input for receiving a data signal;
a signal output for connection to the laser diode;
a modulator for modulation the data signal;
a current infeed connected to the signal output and serving for the supply of a bias current;
a coupling capacitor between the output of the modulator and the signal output, for forming a high-pass filter with the differential resistor of the laser diode connected to the signal output; and
an active compensation circuit having:
a low-pass filter connected to the output of the modulator,
a voltage inverter connected to the low-pass filter and serving for inverting the voltage generated by the low-pass filter in accordance with the low-pass filter transfer function;
a voltage follower connected to the output of the voltage inverter; and
a converter between the output of the voltage follower and the signal output, for generating a current which is inversely proportional to the low-pass filter output voltage.
4. The integrated circuit as claimed in claim 3 , wherein the laser diode is a VCSEL.
5. The integrated circuit as claimed in claim 1 , wherein the laser diode is a VCSEL.