Optical semiconductor diode driver circuit and optical tranceiver module

An optical semiconductor diode driver circuit comprising:

• a pre-driver circuit including functions of amplification but limiting the maximum amplitude of the output voltage in said amplification to a predetermined value, operating as a limiter-type amplifier, so as to amplify and shape an input pulse wave form and generate a voltage pulse;
• and
• an output circuit responsive to said voltage pulse output from said pre-driver circuit to output a drive pulse current to an optical semiconductor diode as an external load, said output circuit including:
• a first transistor and a second transistor whose emitters are commonly connected at a common node;
• and
• a variable constant current source connected to said common node, said voltage pulse output from said pre-driver circuit being input to the base of said first transistor, a collector controller output current output from a collector of said first transistor being input to a base of said second transistor, said second transistor outputting a collector output current as said drive pulse current;
• wherein said variable constant current source of said output circuit includes:
• an emitter-grounded transistor of a size n which is connected in parallel between said common node and the ground connection;
• a unit transistor of a size 1 including a collector connected to said common node and a base connected to the base of said transistor of the size n, in which a constant current in the amount of 1/(n+1) of a current value biased to said common node;
• and
• an error amplifying/feedback circuit network for supplying a feedback signal to the base of said transistor of the size n and the base of said transistor of the size 1 to always maintain zero as the voltage difference between the emitter of said unit transistor and the ground connection.

An optical semiconductor diode driver circuit comprising;

• a pre-driver circuit including functions of amplification but limiting the maximum amplitude of the output voltage in said amplification to a predetermined value, operating as a limiter-type amplifier, so as to amplify and shape an input pulse wave form and generate a voltage pulse;
• and
• an output circuit responsive to said voltage pulse output from said pre-driver circuit to output a drive pulse current to an optical semiconductor diode as an external load, said output circuit including:
• a first transistor and a second transistor whose emitters are commonly connected at a common node;
• and
• a variable constant current source connected to said common node, said voltage pulse output from said pre-driver circuit being input to a base of said first transistor, a control controller output current output from a collector of said first transistor being input to a base of said second transistor, said second transistor outputting a collector output current as said drive pulse current;
• wherein said variable constant current source of said output circuit includes:
• a first current mirror circuit and a first reference current generating source,
• said first current mirror circuit including in combination an emitter-grounded transistor having a size n×m and having a collector connected between said common node and the ground connection, and a transistor having a size m and paired with said transistor having the size n×m,
• said first reference current generating source introducing into said first current mirror circuit a constant current in the amount of 1/n of the current value biased to the common node.

An optical semiconductor diode driver circuit comprising:

• a pre-driver circuit including functions of amplification but limiting the maximum amplitude of the output voltage in said amplification to a predetermined value, operating as a limiter-type amplifier, so as to amplify and shape an input pulse wave form and generate a voltage pulse;
• and
• an output circuit responsive to said voltage pulse output from said pre-driver circuit to output a drive pulse current to an optical semiconductor diode as an external load, said output circuit including:
• a first transistor and a second transistor whose emitters are commonly connected at a common node;
• and
• a variable constant current source connected to said common node, said voltage pulse output from said pre-driver circuit being input to a base of said first transistor, a control controller output current output from a collector of said first transistor being input to a base of said second transistor, said second transistor outputting a collector output current as said drive pulse current;
• wherein a reference current generating source includes:
• a second current mirror circuit connected to a power source line;
• a second reference current generating circuit supplying a current to be injected into said second current mirror circuit;
• and
• another constant current output transistor connected in parallel with said second current mirror circuit output transistor to introduce to the base of said second transistor a compensation bias current for the purpose of always maintaining a constant pulse width against changes in amplitude of the output pulse current.