Receiver Optical Module Stacked Photodiode Pre-Amplifier
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Solution Overview
Problem
The existing receiver optical modules face challenges in mounting pre-amplifiers due to restricted space, leading to potential degradation of photodiode sensitivity when the photodiode is offset from its optical position, especially as pre-amplifiers expand in size.
Innovation Solution
The solution involves a receiver optical module design that includes a sub-mount made of insulating material mounting the photodiode, which is then attached to a pre-amplifier with adhesive, and a stem with lead terminals for electrical connection, allowing for increased flexibility in the placement of the photodiode relative to the axis of the receptacle and enabling the use of larger pre-amplifiers without elongating bonding wires.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pre-amplifier size is increased to accommodate more functions, then pre-amplifier functionality is improved, but mounting space on the stem is reduced
Solution Approach 1:
The invention divides the mounting structure into multiple levels: the stem provides the primary mounting platform, while the pre-amplifier is positioned on the stem with the photodiode mounted on top of the pre-amplifier. This vertical segmentation allows larger pre-amplifiers to be accommodated without consuming excessive horizontal mounting space on the stem.
Solution Approach 2:
The invention transitions from a two-dimensional mounting approach (components placed side-by-side on the stem surface) to a three-dimensional arrangement (photodiode stacked vertically on top of the pre-amplifier, which itself is mounted on the stem). This dimensional change effectively utilizes vertical space, allowing larger pre-amplifiers while maintaining compact overall footprint.
2Adaptability or versatility
If photodiode is offset from optical position to accommodate larger pre-amplifier, then pre-amplifier size is increased, but photodiode sensitivity is degraded
Solution Approach 1:
The invention resolves the positioning conflict by moving the photodiode to a higher vertical level (on top of the pre-amplifier) rather than forcing it to share the same horizontal plane. This allows the photodiode to maintain its optimal optical alignment while the pre-amplifier can be larger, as the vertical stacking eliminates horizontal space competition.
Solution Approach 2:
The pre-amplifier acts as an intermediary platform that supports the photodiode. By positioning the photodiode on top of the pre-amplifier rather than beside it, the pre-amplifier serves as a mediator that enables both the photodiode's optimal positioning and the pre-amplifier's larger size to coexist without compromising sensitivity.
3Adaptability or versatility
If bonding wires are elongated to connect distant pads, then pre-amplifier can be larger, but wire length is increased causing signal degradation
Solution Approach 1:
The invention shortens bonding wire lengths by utilizing vertical stacking. The photodiode is positioned directly above the pre-amplifier, allowing bonding wires to connect vertically between corresponding pads on the photodiode and pre-amplifier. This vertical connection path is significantly shorter than horizontal connections would require, maintaining signal quality while allowing larger pre-amplifier dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances the freedom of photodiode placement, allowing it to be positioned closer to the axis while being slightly offset, maintaining sensitivity and accommodating larger pre-amplifiers, thus preventing sensitivity degradation and optimizing assembly efficiency.
Implementation Method 1
The PD receives the optical signal and generates a photocurrent corresponding to the optical signal
Implementation Method 2
The pre-amplifier mounts the sub-mount accompanying with the PD thereon with an adhesive
Data Source
AI summary
A receiver optical module that receives an optical signal and generating an electrical signal corresponding to the optical signal is disclosed. The module includes a photodiode (PD), a sub-mount, a pre-amplifier, and a stem. The sub-mount, which is made of insulating material, mounts the PD thereon. The pre-amplifier, which receives the photocurrent generated by the PD, mounts the PD through the sub-mount with an adhesive. The pre-amplifier generates an electrical signal corresponding to the photocurrent and has signal pads and other pads. The stem, which mounts the pre-amplifier, provides lead terminals wire-bonded with the signal pads of the pre-amplifier. The signal pads make distances against the sub-mount that are greater than distances from the other pads to the sub-mount.