Folded Sampler Circuitry for Gain and S11 Decoupling
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Solution Overview
Problem
Current sampler circuitry faces challenges in achieving high bandwidth and gain while maintaining a good S11 performance, with a strong trade-off between gain and S11 parameter, and struggles with voltage headroom and current scaling, particularly in high-resolution applications.
Innovation Solution
The implementation of a 'folded' sampler circuitry using a current mirror approach, which splits the primary current path into two separate paths, allowing for programmable gain adjustment and improved S11 performance by decoupling the S11 parameter from the load circuitry, and utilizing impedances to boost gain at high frequencies without affecting the S11 parameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If gain is increased in sampler circuitry, then bandwidth and signal amplification are improved, but S11 performance deteriorates
Solution Approach 1:
The sampler circuitry is divided into two separate current paths: a first current path dedicated to S11 performance and a second current path dedicated to gain and bandwidth. This segmentation allows each path to be optimized independently, resolving the trade-off between gain and S11 performance
Solution Approach 2:
A current mirror circuit is introduced as an intermediary between the input voltage signal and the load circuitry. The current mirror converts the voltage signal to current signals in a controlled manner, enabling gain enhancement through current scaling while maintaining good S11 performance through proper impedance matching
2Use of energy by moving object
If voltage headroom is reduced to improve power efficiency, then power consumption decreases, but current scaling capability is limited
Solution Approach 1:
The circuit skips the traditional voltage amplification stage by directly converting the input voltage signal to current signals using the current mirror. This allows the circuit to achieve high gain through current scaling in the current domain without requiring large voltage headroom, thus reducing power consumption while maintaining current scaling capability
3Speed
If impedance is increased to boost gain at high frequencies, then bandwidth is improved, but S11 performance is affected
Solution Approach 1:
The circuit separates the functions of S11 matching and bandwidth enhancement into different current paths. The first current path maintains good S11 performance through proper impedance matching, while the second current path achieves bandwidth enhancement through controlled impedance transformation in the current mirror, allowing both objectives to be met simultaneously
Data Source
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AI summary
Sampler circuitry operable based on a differential input voltage signal provided between first and second input nodes, the sampler circuitry comprising: load circuitry comprising sampler switches configured to sample first and second load currents which define a differential current signal, the load circuitry having first and second load nodes and a biasing node; a power supply node for connection to a voltage source; a first current path extending from the power supply node to the first load node to provide the first load current at the first load node for use by the load circuitry, wherein a first supply-connection impedance is connected along the first current path between the power supply node and the first load node; a second current path extending, in parallel with the first current path, from the power supply node to the second load node to provide the second load current at the second load node for use by the load circuitry, wherein a second supply-connection impedance is connected along the second current path between the power supply node and the second load node; first and second input-connection impedances; and control circuitry, wherein: the control circuitry is configured, based on measurement of a common mode voltage indicative of a common mode between voltages at the first and second load nodes, to control a biasing signal provided to the biasing node of the load circuitry to regulate the common mode voltage; and the first and second input nodes are connected to the first and second load nodes via the first and second input-connection impedances, respectively, so that the differential current signal is dependent on the differential input voltage signal.