LD driver with an improved falling edge of driving signal and optical transmitter providing the same
AssigneeSumitomo Electric Industries, Ltd.
InventorKeiji Tanaka
Life of this patent
Estimating the term…
Abstract
An LD driver to generate an asymmetrical driving current with a relatively faster falling edge and an optical transmitter having the LD driver are disclosed. The LD driver includes a primary driver and the sub-driver connected in parallel to the primary driver. The primary driver converts the input signal or the delayed signal delayed from the input signal into the primary current. The sub-driver generates a symmetrical current tracing the input or the delayed signal, and an asymmetrical current formed by the OR operation between the input and delayed signals. The driving current is formed by adding the primary current, the symmetrical current and the asymmetrical current.
Claims15
An LD driver to generate a driving current with a falling edge faster than a leading edge thereof, comprising:
- a delay unit configured to receive an input signal to output a delayed signal delayed by a variable period with respect to said input signal;
- a primary driver configured to convert one of said input signal and said delayed signal to a primary current by a first conversion ratio;
- and
- a sub-driver connected in parallel to said primary driver, said sub-driver including a symmetrical driver and an asymmetrical driver, wherein said symmetrical driver converting one of said delayed signal and said input signal into a symmetrical current by a second conversion ratio, wherein said asymmetrical driver including two arithmetic units, each carrying out an OR operation between said input signal and said delayed signal and converting a result of said OR operation into an asymmetrical current by a third conversion ratio,
- wherein said LD driver outputs said driving current by adding said primary current, said symmetrical current and said asymmetrical current.
An optical transmitter, comprising:
- a transmitter optical subassembly including a laser diode and an active device connected in parallel with respect to said laser diode, said active device shunting a current provided to said laser diode by receiving a driving signal with a falling edge faster than a leading edge;
- and
- an LD driver including a primary driver and a sub-driver connected in parallel to said primary driver,
- wherein said primary driver converts one of input signal input to said LD driver and a delayed signal delayed by a variable period with respect to said input signal into a primary current by a first conversion ratio, and said sub-driver includes a symmetrical driver and an asymmetrical driver, said symmetrical driver converting one of said input signal and said delayed signal into a symmetrical current by a second conversion ratio, said asymmetrical driver including two arithmetic units, each carrying out an OR operation between said input signal and said delayed signal and converting a result of said OR operation into an asymmetrical current by a third conversion ratio,
- wherein said driving signal provided to said active device in said transmitter optical subassembly is a sum of said primary current, said symmetrical current and said asymmetrical current.
Dependencies are inferred from the claim text.