Method and apparatus for providing a modulation current
US7154923B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 24, 2004 |
| Grant date | Dec 26, 2006 |
| Priority date | — |
| Expiry date | Jan 8, 2025 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01S5/042
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Techniques are disclosed for providing modulation current that includes output impedance compensation with a feed-forward bandwidth enhancement and pre-distortion modulation to control waveform transition symmetry. A feedback circuit senses output node voltage and increases the overdrive voltage of a current source. This offsets the loss of current due to channel length modulation and increases the effective output impedance of the source. A feed-forward circuit enhances the bandwidth of the impedance compensation feedback loop. Waveform transition symmetry is improved by pre-distorting a laser modulation current by introducing an undershoot current on the falling edge of the modulating current.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.