Transimpedance Amplifier Circuit With Shared Current Source
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Solution Overview
Problem
Known transimpedance amplifiers face issues with high power consumption and noise, as well as bandwidth limitations, which affect their performance in applications such as optical communication.
Innovation Solution
The proposed solution involves sharing a current source between two transimpedance amplifiers, each with a MOS transistor amplification stage, allowing for reduced power consumption and improved signal-to-noise ratio through differential operation and optimized photodiode configuration, which also enhances spatial sensitivity and radiation diagram aperture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single transimpedance amplifier with a current source biased amplification stage is used, then the circuit can amplify the current signal from the photodiode, but the power consumption is large
Solution Approach 1:
The patent divides the transimpedance amplifier into two separate amplifiers (first and second transimpedance amplifiers) that share a common current source. Each amplifier handles a portion of the signal processing, allowing the system to achieve the required amplification capability while reducing the total power consumption compared to a single high-power amplifier design.
Solution Approach 2:
The current source is designed to serve multiple functions by being shared between two transimpedance amplifiers. This single current source provides bias current to both amplifiers, eliminating the need for separate current sources and reducing overall power consumption while maintaining the amplification functionality.
2Device complexity
If a single transimpedance amplifier is used, then the circuit structure is simple, but the noise level is large
Solution Approach 1:
By segmenting the amplification function into two separate transimpedance amplifiers, the noise from a single amplifier is distributed and reduced. The differential configuration of the two amplifiers further helps in canceling common-mode noise, improving the signal-to-noise ratio while keeping the overall circuit structure relatively simple.
Solution Approach 2:
The patent converts the potential harm of having a more complex circuit into a benefit by using two amplifiers with a shared current source. This configuration transforms the additional circuit elements into a noise-reduction mechanism, where the differential operation of the two amplifiers cancels out common noise sources, improving the overall signal quality.
3Area of stationary object
If a single transimpedance amplifier is used, then the circuit is compact, but the bandwidth is limited
Solution Approach 1:
The bandwidth limitation of a single transimpedance amplifier is overcome by segmenting the amplification function into two amplifiers. This segmentation allows for optimized frequency response in each amplifier, and their combined operation extends the overall bandwidth while maintaining a compact circuit area through the shared current source architecture.
Data Source
AI summary
The present disclosure relates to a device comprising a first transimpedance amplifier comprising a first amplification stage with a first MOS transistor, a second transimpedance amplifier comprising a second amplification stage with a second MOS transistor, and a current source series-connected with the first and second amplification stages, the current source having a first terminal coupled to the drain of the first MOS transistor and a second terminal coupled to the drain of the second MOS transistor.