Double-Base Current Circulator Mirrors for Linear Wideband Output
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Solution Overview
Problem
Current mirrors face challenges in achieving high linearity and wide signal bandwidth, as linearity is often traded off against bandwidth and power, limiting their dynamic range in applications such as communication and industrial systems.
Innovation Solution
A current mirror arrangement with a double-base current circulator is introduced, which includes a current mirror and a double-base current circulator that splits the mirrored current into two branches, each with a cascode configuration of transistors, to mitigate parasitic capacitance effects and improve linearity and bandwidth by circulating nonlinear currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional current mirror is used to achieve high linearity, then the signal bandwidth is limited due to parasitic capacitance effects
Solution Approach 1:
The current mirror output is segmented into multiple parallel branches (at least two), with each branch containing a current circulator circuit. This segmentation distributes the total output current across multiple paths, reducing the current magnitude through individual parasitic capacitances and thereby extending the linear bandwidth while maintaining overall linearity.
Solution Approach 2:
Current circulators are introduced as intermediary circuits between the main current mirror and the output load. These circulators actively compensate for nonlinear currents generated by parasitic capacitances in each branch, canceling out their harmful effects and extending the linear operating range without compromising bandwidth.
2Speed
If the signal bandwidth is increased in a current mirror, then linearity deteriorates due to parasitic capacitance effects
Solution Approach 1:
The current circulator circuits employ feedback mechanisms where a portion of the output current is fed back through the circulator path. This feedback actively counteracts the nonlinear currents generated by parasitic capacitances at high frequencies, maintaining linearity across an extended bandwidth by dynamically compensating for frequency-dependent effects.
Solution Approach 2:
Current circulators serve as intermediary compensation circuits that mediate between the high-bandwidth requirement and linearity preservation. By introducing these intermediate stages that specifically target and cancel nonlinear effects, the system achieves both wide bandwidth and high linearity simultaneously.
3Speed
If multiple current branches are used to extend bandwidth, then device complexity increases
Solution Approach 1:
The circuit is segmented into modular current circulator units that can be replicated in parallel. Each unit is a self-contained module handling a specific branch, making the overall complex system manageable through standardized modular building blocks that simplify design and analysis.
Solution Approach 2:
The current circulator circuit is designed as a universal multi-functional block that simultaneously achieves multiple objectives: it extends bandwidth, maintains linearity, and provides current splitting. This multi-functionality reduces overall circuit complexity by consolidating multiple functions into a single standardized module rather than requiring separate circuits for each function.
Data Source
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AI summary
A current mirror arrangement with a current mirror and a double-base current circulator is disclosed. The current mirror is configured to receive an input current (IIN) and generate a mirrored current (IM), where IM=K∗IIN. The current circulator, coupled to the current mirror, is configured to convey the mirrored current to an output node of the arrangement. The current circulator is a double-base current circulator and includes a first branch configured to receive a first branch current (I1b), where I1b=m∗IM, where m is a positive number less than 1, and further includes a second branch configured to receive a second branch current (I2b), where I2b=(1-m)*IM. The first branch includes a cascode of transistors Q3 and Q5, configured to provide I1b to an output node. The second branch includes a transistor Q4 configured to provide I2b to the output node, where it is combined with I1b.