Electro-Optical Mixer With Switchable Matching for Direct RF Conversion
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Solution Overview
Problem
Existing optical signal conversion and upconversion systems in radar and data transmission are complex, costly, and inefficient, with components like transimpedance amplifiers and Mach-Zehnder modulators increasing noise, power loss, and chip area, making them unsuitable for low-power applications and high-frequency operations.
Innovation Solution
An electro-optical mixer with integrated photodiode, partial matching networks, and decoupling elements, allowing for direct electrical signal generation and frequency adjustment without a transimpedance amplifier, using H-bridge switches for selective frequency band operation and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a transimpedance amplifier is used to convert optical signals to electrical signals, then the conversion function is achieved, but the system complexity increases and chip area increases by approximately 0.25 mm²
Solution Approach 1:
The patent combines the transimpedance amplifier function and mixer function into a single integrated electro-optical mixer device. The photodiode directly generates the electrical signal through optical-to-electrical conversion while the H-bridge circuit simultaneously performs mixing operations, eliminating the need for separate TIA and mixer components.
Solution Approach 2:
The integrated electro-optical mixer performs multiple functions within a single device: optical signal detection, electrical signal generation, frequency mixing, and signal amplification. This multi-functional approach replaces the traditional multi-component chain (photodiode + TIA + mixer + VGA), reducing system complexity while maintaining all necessary capabilities.
2Reliability
If a transimpedance amplifier is used for optical-to-electrical conversion, then the conversion is achieved, but power loss increases and efficiency decreases
Solution Approach 1:
By merging the TIA and mixer functions into one integrated circuit, the patent eliminates intermediate signal transmission stages that cause power loss. The direct coupling between the photodiode and H-bridge mixing circuit reduces signal degradation and minimizes energy dissipation across multiple components.
3Adaptability or versatility
If passive filter components are used for frequency selection, then channel selection is achieved, but noise increases due to parasitic resistance
Solution Approach 1:
The patent replaces traditional passive RC or LC filter circuits with an active frequency-selective network implemented through the H-bridge switching circuitry. This electronic approach eliminates the parasitic resistance inherent in passive components while maintaining frequency selection capability through controlled switching operations.
4Ease of operation
If a Mach-Zehnder modulator is used to set optical power to zero, then the switching function is achieved, but the chip area increases and high control voltages (2-3 V) are required
Solution Approach 1:
The patent extracts the switching function from the Mach-Zehnder modulator and implements it directly within the H-bridge circuit using electronic switches. This removes the bulky MZM component while retaining the essential on/off switching capability needed for modulation and signal processing.
Solution Approach 2:
The patent replaces the optical-based Mach-Zehnder modulator with an electronic switching mechanism in the H-bridge circuit. This substitution eliminates the need for high-voltage optical modulation while achieving the same functional outcome through electronic control of current paths.
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
The solution reduces system complexity, power consumption, noise, and chip area, enabling efficient, low-power operation with adjustable bandwidth and frequency selection, suitable for both broadband and narrowband applications.
Implementation Method 1
at least one photodiode PD for converting an incident optical signal into an electrical signal
Data Source
AI summary
The invention relates to an electro-optical mixer having an electrical output, the electro-optical mixer including:a photodiode for converting an incident optical signal,a first terminal,a second terminal,where a first voltage supply can be connected to the first terminal and a second voltage supply can be connected to the second terminal, or a first power supply can be connected to the first terminal and a second power supply can be connected to the second terminal,a terminal for a small-signal ground potential for the first voltage supply and the second voltage supply,a first partial matching network which is arranged on the anode side of the photodiode, wherein a portion of the first partial matching network is switchably connectable to the terminal for the second voltage supply, and wherein another portion of the first partial matching network is switchably connectable to the terminal for the small-signal ground potential, anda second partial matching network which is arranged on the cathode side of the photodiode, wherein a portion of the second partial matching network is switchably connectable to the terminal for the first voltage supply, and wherein another portion of the second partial matching network is switchably connectable to the terminal for the small-signal ground potential, and where an electrical output signal can during operation be provided between sides of a first decoupling element and a second decoupling element facing away from the photodiode.