Systems and methods for using cascoded output switch in low voltage high speed laser diode and EAM drivers

A laser diode/electro-absorption-modulator (LD/EAM) driver comprising:

• a cascoded output switch having a pair of output devices and a pair of cascode devices;
• a resistor providing tail current to the output devices;
• a predriver circuit receiving an input signal and controlling the output devices;
• a feedback circuit coupled to the resistor to control a modulation current of the output devices by control of bias on the predriver circuit;
• a common mode feedback circuit providing modulation dependent currents for the predriver;
• and,
• a pulldown variance circuit coupled to the predriver, the pulldown variance circuit causing a turnoff current of the predriver to be larger than a turn-on current of the predriver.

A laser diode/electro-absorption-modulator (LD/EAM) driver comprising:

• a cascoded output switch having a pair of output devices and a pair of cascode devices;
• a resistor providing tail current to the output devices;
• a predriver circuit receiving an input signal and controlling the output devices;
• a feedback circuit coupled to the resistor to control a modulation current of the output devices by control of bias on the predriver circuit;
• a common mode feedback circuit providing modulation dependent currents for the predriver circuit;
• a cascode bias circuit coupled to bias the cascode devices to a bias voltage responsive to a power supply voltage, an output bias current and the modulation current;
• and,
• a pulldown variance circuit coupled to the predriver, the pulldown variance circuit causing a turnoff current of the predriver to be larger than a turn-on current of the predriver.

A laser diode/electro-absorption-modulator (LD/EAM) driver comprising:

• a cascoded output switch having a pair of output devices and a pair of cascode devices;
• a resistor providing tail current to the output devices;
• a predriver circuit receiving an input signal and controlling the output devices;
• a feedback circuit coupled to the resistor to control a modulation current of the output devices by control of bias on the predriver circuit;
• a common mode feedback circuit providing modulation dependent currents for the predriver circuit;
• a cascode bias circuit coupled to bias the cascode devices to a bias voltage responsive to a power supply voltage, an output bias current and the modulation current;
• a PTAT bandgap reference circuit to generate biasing currents with positive temperature coefficients for the predriver circuit;
• and,
• a pulldown variance circuit coupled to the predriver, the pulldown variance circuit causing a turnoff current of the predriver to be larger than a turn-on current of the predriver.