Optical Transmitter Module Termination Circuit Segmentation
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Solution Overview
Problem
Conventional optical transmitter modules face challenges in size reduction while maintaining excellent optical transmission waveform quality due to the need for large capacitors, which occupy space and hinder the integration of other essential components in smaller packages like the 5.6 mm TO-CAN package.
Innovation Solution
The optical transmitter device incorporates a printed circuit board with a first and second termination resistor circuit, where the lower cutoff frequency and upper cutoff frequency of the first termination resistor circuit correspond to each other, and the impedance in the pass frequency band of both circuits matches, allowing for a smaller module size with flat impedance characteristics over a wide range of frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a multi-layered ceramic capacitor with capacitance value of 0.01 microfarads or more is installed in an optical module to maintain broadband impedance characteristics, then excellent optical transmission waveform quality is achieved, but the module size cannot be reduced below conventional dimensions
Solution Approach 1:
The broadband termination resistor circuit is segmented into two separate narrowband termination resistor circuits: a first narrowband termination resistor circuit with lower cutoff frequency and a second narrowband termination resistor circuit with upper cutoff frequency. This segmentation eliminates the need for large multi-layered ceramic capacitors while achieving equivalent broadband impedance characteristics through coordinated operation of the two narrower circuits.
Solution Approach 2:
The solution transitions from a single broadband termination circuit requiring large capacitors to two narrowband termination circuits operating in complementary frequency ranges. By dividing the frequency spectrum into two bands and using separate termination circuits for each, the patent achieves broadband performance without the space-consuming capacitors.
2Reliability
If a termination resistor circuit with large capacitance value is used to maintain low frequency impedance characteristics, then excellent waveform quality is achieved, but space for other essential components is eliminated
Solution Approach 1:
The termination function is segmented across two separate circuits with different frequency characteristics. The first narrowband termination resistor circuit handles lower frequency ranges while the second handles upper frequency ranges, eliminating the need for large capacitance values in either circuit and enabling better component integration.
3Volume of moving object
If the optical module is reduced to 5.6 mm TO-CAN package size to meet MSA standards, then size requirements are satisfied, but space for multi-layered ceramic capacitor and other components becomes insufficient
Solution Approach 1:
By segmenting the broadband termination circuit into two narrowband circuits, the patent eliminates the need for large multi-layered ceramic capacitors, making component layout feasible in the constrained 5.6 mm TO-CAN package space while meeting MSA size standards.
Solution Approach 2:
The patent replaces expensive and space-consuming multi-layered ceramic capacitors with simpler, smaller termination resistor circuit implementations that use standard small-value capacitors and resistors, making the design economically viable and manufacturable in small packages.
Data Source
AI summary
Provided are an optical transmitter device and an optical transmitter module which are capable of reducing the optical transmitter module size while maintaining a state where an excellent optical transmission waveform quality is obtained over a wide range of frequencies. The optical transmission module (2) includes a semiconductor laser diode device (10), an optical modulator device (12), and a first termination resistor circuit (14-1). A printed circuit board (4) includes a driver IC (16) and a second termination resistor circuit (14-2). A lower cutoff frequency of the first termination resistor circuit (14-1) and an upper cutoff frequency of the second termination resistor circuit (14-2) correspond to each other. An impedance of the first termination resistor circuit (14-1) in a pass frequency band thereof and an impedance of the second termination resistor circuit (14-2) in a pass frequency band thereof correspond to each other.