Laser diode driver damping circuit
AssigneeTexas Instruments Incorporated
InventorsDouglas Warren Dean, Craig Matthew Brannon
Life of this patent
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Abstract
A damping circuit having an input terminal and an output terminal is described. The damping circuit comprises a driver having an input and an output; an RC circuit coupled between the input terminal and the output; and a resistor coupled between the output and the output terminal, wherein the RC circuit delays passing a signal from the output terminal to the input terminal and a low impedance associated with the driver generally reduces ringing.
Claims16
A damping circuit having an input terminal and an output terminal, the damping circuit comprising:
- a current source having a first current;
- a first current mirror coupled to the current source, the first current mirror having an associated current approximately equal to the first current;
- a plurality of slave devices coupled to the compensated current mirror, the slave devices having an associated current approximately equal to a scaled version of the first current;
- a second current mirror coupled to the current source and the first current mirror, the second current mirror having an associated current approximately equal the first current;
- a driver having first and second driver inputs and a driver output;
- a first resistor circuit coupled between the driver inputs;
- a capacitor coupled between the first input and a low voltage supply;
- and
- a second resistor coupled between the driver output and the output terminal;
- wherein the first resistor and the capacitor delay passing a signal from the output terminal to the input terminal and a low impedance associated with the driver generally reduces ringing.
A laser diode write driver for driving a light source, comprising:
- a feedback loop coupled for receiving an input current signal, the feedback loop operative for reaching a steady state, where at least one device within the feedback loop receives all of the current for transmitting a first current signal;
- a current mirror adapted to receive the first current signal, the current mirror operative for replicating the first current signal and transmitting a second current signal;
- a differential device adapted to receive the second current signal, the differential device operative for steering current in at least one direction and transmitting a first voltage signal;
- a buffering device adapted to receive the first voltage signal, the buffering device operative for transmitting a second voltage signal;
- an output device coupled to the buffering device and operative for transmitting a driver output signal that drives the light source in response to receiving the second voltage signal;
- and
- a damping circuit having an input terminal and an output terminal coupled to the light source comprising:
- a driver having an input and an output;
- an RC circuit coupled between the input terminal and the output;
- and a resistor coupled between the output and the output terminal, wherein the RC circuit delays passing a signal from the output terminal to the input terminal and a low impedance associated with the driver generally reduces ringing.
A damping circuit having an input terminal and an output terminal, the damping circuit comprising:
- a driver having an input and an output;
- an RC circuit coupled between the input terminal and the output;
- and
- a resistor coupled between the output and the output terminal;
- wherein the RC circuit delays passing a signal from the output terminal to the input terminal and a low impedance associated with the driver generally reduces ringing.
Dependencies are inferred from the claim text.