Differential-to-Single-Ended Converter With Offset Cancellation
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Solution Overview
Problem
Conventional high-speed differential to single-ended converting circuits face issues with jitter and common-mode drift due to mismatched differential currents, require diode connected transistors to prevent turning off, and result in increased power consumption and distortion.
Innovation Solution
A differential to single-ended converting circuit design that employs a transconductance circuit, offset cancellation circuit, and transimpedance circuits with feedback resistors and operational amplifiers to equalize duty cycles and eliminate diode connected transistors, using controllable current sources and inverters to generate single-ended output voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If diode connected transistors are used to prevent turning off for high-speed operation, then operating speed is improved, but power consumption increases and distortion occurs
Solution Approach 1:
The patent changes the operating parameters by using controllable current sources instead of diode-connected transistors. The current sources can be dynamically adjusted to maintain high-speed operation without the continuous power consumption penalty of diode-connected configurations, thereby reducing distortion and power usage while preserving speed performance.
Solution Approach 2:
The patent extracts and removes the diode-connected transistors from the circuit configuration. By eliminating these components that cause excessive power consumption and distortion, the circuit achieves high-speed operation through alternative mechanisms (controllable current sources) that do not suffer from the same drawbacks.
2Speed
If diode connected transistors are used to prevent turning off for high-speed operation, then operating speed is improved, but circuit distortion increases
Solution Approach 1:
The patent changes the operational parameters by replacing diode-connected transistors with controllable current sources. This parameter change allows the circuit to maintain high-speed operation while significantly reducing the nonlinear distortion inherent in diode-connected configurations, as the current sources can be precisely controlled to operate in their linear regions.
Solution Approach 2:
The patent extracts and eliminates the diode-connected transistors that are the source of circuit distortion. By removing these problematic components and replacing them with controllable current sources, the harmful distortion effects are eliminated while preserving the high-speed operational capability.
3Speed
If larger size and higher transconductance transistors are used to prevent turning off, then high-speed operation is achieved, but device complexity increases
Solution Approach 1:
The patent substitutes the physical enlargement and complex configuration of transistors with an electronic control mechanism. Instead of using larger, more complex transistors to prevent turning off, the invention uses controllable current sources that can be precisely regulated, thereby achieving high-speed operation without increasing device complexity or physical size.
4Device complexity
If conventional differential to single-ended converting circuit is used, then circuit structure is simple, but jitter and common-mode drift occur due to mismatched differential currents
Solution Approach 1:
The patent introduces controllable current sources as intermediary elements between the differential input and single-ended output. These current sources act as mediators that can be precisely controlled to maintain balanced differential currents, thereby eliminating jitter and common-mode drift while preserving the relative simplicity of the circuit structure.
Solution Approach 2:
The patent employs feedback mechanisms through controllable current sources that can sense and adjust differential current imbalances. This feedback control ensures that differential currents remain matched, preventing jitter and common-mode drift, while the overall circuit structure remains relatively simple compared to more complex balancing networks.
Data Source
AI summary
A differential to single ended converting circuit includes a transconductance circuit having input terminals for receiving differential input voltages and having a first current output terminal for outputting a first current and a second current output terminal for outputting a second current; an offset cancellation circuit having a first controllable current source connected to the first current output terminal and a second controllable current source connected to the second current output terminal; a first transimpedance circuit having an input terminal connected to the first current output terminal and an output terminal for outputting a first voltage; a second transimpedance circuit having an input terminal connected to the second current output terminal and an output terminal for outputting a second voltage; and a first inverter having an input terminal connected to the output terminal of the first transimpedance circuit and an output terminal for outputting a first single ended output voltage.