Folded Current Sampler Circuit for High Gain and Stable S11
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Solution Overview
Problem
Current sampler circuitry faces challenges in achieving high gain without degrading the S11 performance, experiencing trade-offs between gain and S11 parameters, and struggles with voltage headroom and current scaling, particularly in high-resolution applications.
Innovation Solution
The proposed sampler circuitry employs a 'folded' structure with current mirror circuitry, allowing for programmable gain and improved S11 performance by decoupling the S11 parameter from the gain, utilizing a primary and secondary current path configuration with current mirror transistors and impedance networks to enhance gain at high frequencies while maintaining optimal S11 performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional sampler circuitry uses traditional voltage-to-current conversion, then the circuit can operate with simple structure, but the gain is limited and S11 performance degrades at high frequencies
Solution Approach 1:
The circuit is divided into two separate current paths: a primary current path for voltage-to-current conversion and a secondary current path for gain enhancement. This segmentation allows each path to be optimized independently, with the primary path maintaining S11 performance and the secondary path providing gain through current mirror circuitry.
Solution Approach 2:
A current mirror circuit acts as an intermediary between the primary and secondary current paths. It transfers the converted current signal while providing gain, decoupling the S11 parameter from the gain requirement and allowing high-frequency operation without performance degradation.
2Power
If the circuit uses higher gain configuration, then the signal amplification improves, but the voltage headroom is reduced
Solution Approach 1:
The circuit replaces traditional voltage amplification mechanisms with current-mode operation and current mirror circuitry. This substitution allows gain to be achieved through current replication rather than voltage amplification, preserving voltage headroom while providing the required signal amplification.
3Ease of manufacture
If traditional voltage-mode operation is used, then the circuit design is straightforward, but bandwidth is limited and high-frequency performance is poor
Solution Approach 1:
The circuit transitions from static voltage-mode operation to dynamic current-mode operation with time-interleaved sampling. This allows the circuit to respond more quickly to input changes, extending bandwidth and improving high-frequency performance while maintaining design simplicity through systematic current path configuration.
4Measurement precision
If current scaling is increased for high-resolution applications, then the signal precision improves, but the circuit becomes more complex and harder to scale
Solution Approach 1:
The current mirror circuitry provides universal gain enhancement that can be applied to multiple signal paths simultaneously. The same basic current mirror structure serves both to provide gain and to enable current scaling for high-resolution applications, reducing overall circuit complexity while improving precision.
Data Source
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AI summary
Sampler circuitry, comprising: an input node configured to receive an input voltage signal; a primary current path connected between high and low voltage supply nodes; a secondary current path connected between high and low voltage supply nodes; current mirror circuitry; and load circuitry comprising sampler switches operable to sample a current signal, wherein: the input node is defined along the primary current path, the primary current path configured to carry a primary current dependent on the input voltage signal; the current mirror circuitry comprises a primary side and a secondary side, the primary side connected along the primary current path and the secondary side connected along the secondary current path so that a secondary current dependent on the primary current is caused to flow along the secondary current path; and the load circuitry is connected along the secondary current path so that the secondary current at least partly forms the current signal.