Current-Mode Feed Forward Equalizer Sampling for High Bandwidth
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Solution Overview
Problem
Traditional feed forward equalizers struggle with high sampling frequencies due to the need for large and expensive switches, complex clocking, and increased resource consumption, leading to inefficiencies and difficulty in maintaining signal integrity.
Innovation Solution
Converting input voltage signals to current mode sampling using transistors and capacitors, enabling efficient current sampling that reduces noise and allows for smaller switches, thereby increasing bandwidth and reducing resource consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional voltage mode sampling is used in feed forward equalizers, then signal integrity can be maintained, but the switches become large and expensive, device complexity increases, and resource consumption increases
Solution Approach 1:
The patent replaces the traditional voltage mode sampling mechanism with a current mode sampling mechanism. This substitution fundamentally changes the domain of operation from voltage to current, allowing the use of smaller, less complex switches that operate in the current domain. The current mode sampler uses current sources and current switches instead of voltage sources and voltage switches, thereby reducing the physical size and complexity of the switching components while maintaining sampling functionality.
Solution Approach 2:
The patent changes the fundamental parameter domain from voltage to current. By operating the sampling circuit in the current domain rather than the voltage domain, the equalizer can use smaller switches with lower capacitance values. This parameter change also affects the noise characteristics and bandwidth of the circuit, enabling high-frequency operation with reduced resource consumption.
2Reliability
If traditional voltage mode sampling is used, then signal integrity is maintained, but noise levels increase and bandwidth is limited
Solution Approach 1:
The patent substitutes voltage mode sampling with current mode sampling, which fundamentally changes the noise characteristics of the sampling circuit. Current mode operation reduces the impact of voltage noise and introduces different noise sources that can be more effectively managed. The current sources used in the sampling circuit have inherently lower noise contributions compared to the voltage switches and capacitors used in traditional voltage mode samplers.
3Speed
If higher sampling frequencies are achieved with traditional switches, then bandwidth increases, but switch size and resource consumption increase significantly
Solution Approach 1:
The patent changes the operating domain from voltage to current, which fundamentally alters the relationship between sampling frequency and switch size. In current mode sampling, the switches handle current signals with much smaller associated capacitances, allowing high-frequency operation without requiring large switch sizes. The current mode switches can operate at higher frequencies because they are not burdened by the large capacitance charging/discharging requirements that plague voltage mode switches at high frequencies.
4Object-affected harmful factors
If current mode sampling is implemented, then noise is reduced and bandwidth is extended, but a different sampling mechanism is required
Solution Approach 1:
The patent replaces the entire voltage mode sampling mechanism with a current mode sampling mechanism. This includes substituting voltage sources with current sources, voltage switches with current switches, and voltage capacitors with current capacitors. The implementation provides a complete circuit diagram showing the current mode sampler integrated with the feed forward equalizer, demonstrating that while the mechanism is different, it is a systematic and implementable alternative that achieves the desired noise reduction and bandwidth extension.
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 current mode sampling approach achieves a 2/π reduction in output noise and extends the bandwidth of discrete time equalizers, enabling higher frequency sampling with smaller, less resource-intensive switches.
Implementation Method 1
a transistor operable to convert an input voltage signal from a linear equalizer into a current
Implementation Method 2
a capacitor to: charge based on the current when the first switch is enabled; and discharge when the second switch is enabled
Data Source
AI summary
Methods, apparatus, systems, and articles of manufacture are described to perform current mode sampling with a feed forward equalizer. An example apparatus includes a transistor operable to convert an input voltage signal from a linear equalizer into a current; a first switch to enable and disable based on a first clock signal; a second switch to enable and disable based on a second clock signal; and a capacitor to: charge based on the current when the first switch is enabled; and discharge when the second switch is enabled.