DQPSK Transmitter Driver Amplitude Control via Temperature Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The complexity of control circuits in DQPSK transmitters is increased by the need to control three bias points, and conventional methods using pilot signals introduce OSNR costs.
Innovation Solution
A feedback control system that separates the driver amplitude control from the modulator feedback, using temperature sensors and compensation modules to adjust the driving amplitude of drivers I and Q, eliminating the need for a pilot signal and simplifying the control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pilot signal method is used to control driving amplitude, then driving amplitude control is achieved, but control circuit complexity increases and OSNR performance deteriorates
Solution Approach 1:
The patent extracts the driving amplitude control function from the modulator feedback path and implements it independently through temperature sensing and compensation circuits for each driver, eliminating the need for pilot signals and reducing control circuit complexity
Solution Approach 2:
The patent introduces temperature sensors as intermediary devices to indirectly monitor and control driver amplitude by detecting temperature changes, avoiding direct complex amplitude measurement and control circuits
2Reliability
If conventional pilot signal method is used to control driving amplitude, then driving amplitude control is achieved, but OSNR performance deteriorates due to additional noise
Solution Approach 1:
The patent removes the pilot signal component from the system entirely, replacing it with independent temperature-based compensation circuits that do not introduce additional noise into the optical signal path
Solution Approach 2:
By using temperature sensors as intermediaries to control driver amplitude, the patent avoids direct electrical control paths that would introduce noise, thereby preserving OSNR performance
3Device complexity
If driving amplitude is not controlled, then control circuit complexity is reduced, but OSNR performance deteriorates
Solution Approach 1:
The patent implements self-service control where each driver has its own temperature sensor and compensation circuit that automatically adjusts the driver amplitude based on real-time temperature conditions, maintaining optimal performance without complex external control
Solution Approach 2:
The patent controls driver amplitude by changing the bias voltage parameter based on temperature measurements, using simple voltage adjustment rather than complex control mechanisms to maintain optimal OSNR performance
Data Source
Figure 1A~1B
Figure 2
Figure 3~4
AI summary
The present invention discloses an apparatus and a method for controlling a driving amplitude of a DQPSK transmitter. The method includes: a DQPSK modulator modulating an optical signal emitted from a CW and without adding with modulated signal; a modulator feedback control unit is connected with a first bias point, a second bias point and a third bias point and controls the first bias point, the second bias point and the third bias point according to a part of the optical signal modulated by the DQPSK modulator; controlling the driving amplitude of a driver I according to temperature change of the driver I; controlling the driving amplitude of a driver Q according to temperature change of the driver Q. The present invention can be used to simplify complexity of the control circuit of the DQPSK transmitter, there is no need to add a pilot signal on the driving amplitude of the driver, and therefore no extra optical signal-to-noise ratio cost would be created.