Interleaved FIR Transmitter With Decoupled DAC Equalization
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Solution Overview
Problem
Existing high-speed data transmission systems face challenges such as high insertion loss, near- and far-end cross-talk, inter-symbol interference, and linearity issues due to limitations in current transmitter designs, particularly with MAC-based FIR filters and current-mode drivers, which result in inefficiencies and increased complexity.
Innovation Solution
A novel transmitter architecture incorporating a self-adjusting two-tap MAC-based FIR filter and a binary-weighted current-steering D/A converter, decoupled from the equalizer design, to achieve flexible and efficient data transmission across channels with reduced power and area consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a MAC-based FIR filter is used for equalization, then the transmitter can be configured for different channel environments, but the power consumption and circuit area increase significantly
Solution Approach 1:
The transmitter is divided into two independent parts: a fixed two-tap MAC equalizer and a configurable binary-weighted current-steering D/A converter. The D/A converter handles the adaptability for different channel environments while the MAC equalizer remains simple and power-efficient. This segmentation allows configuration flexibility without requiring a full MAC-based FIR filter, thus reducing power consumption.
Solution Approach 2:
The binary-weighted current-steering D/A converter serves multiple functions: it acts as both the equalizer output stage and the driver for different channel environments. By configuring the D/A converter's transfer function, the same hardware can adapt to short channel, long channel, and intermediate channel scenarios, eliminating the need for multiple specialized circuits.
2Adaptability or versatility
If a MAC-based FIR filter is used for equalization, then the transmitter can be configured for different channel environments, but the circuit area increases significantly
Solution Approach 1:
The transmitter architecture segments the equalization function from the driver function. The fixed two-tap MAC equalizer uses minimal area, while the configurable adaptation is achieved through the D/A converter's transfer function programming. This segmentation avoids the large area requirement of a full MAC-based FIR filter while maintaining configurability.
Solution Approach 2:
Instead of implementing multiple full MAC-based FIR filters for different channel environments, the patent uses a single simplified MAC equalizer combined with a configurable D/A converter. The D/A converter's transfer function is programmed to copy or emulate the effect of different equalizer configurations, achieving environmental adaptability with minimal area overhead.
3Area of stationary object
If the equalizer and driver are coupled in traditional designs, then the system is compact, but changing the equalizer configuration requires redesigning the entire transmitter
Solution Approach 1:
The patent segments the equalizer (fixed two-tap MAC) from the driver (configurable D/A converter) while maintaining compact integration. The D/A converter's transfer function can be independently programmed for different channel environments without changing the equalizer structure. This segmentation enables easy reconfiguration while keeping the overall system compact.
Solution Approach 2:
The D/A converter is designed with dynamic reconfigurability through its transfer function programming. The same hardware structure can dynamically adapt to different channel environments (short, long, intermediate channels) by changing the D/A converter's operational parameters, eliminating the need for static redesign while maintaining system compactness.
4Speed
If current-mode drivers are used for high-speed transmission, then data transmission speed is improved, but linearity and accuracy deteriorate
Solution Approach 1:
The binary-weighted current-steering D/A converter acts as an intermediary between the digital equalizer output and the analog channel. It provides precise current control with improved linearity by using binary-weighted current sources that can be accurately programmed, thereby maintaining signal integrity and transmission accuracy at high speeds.
Solution Approach 2:
The D/A converter uses parameter changes in its transfer function to optimize linearity and accuracy for different channel environments. By programmatically adjusting the D/A converter's operational parameters (transfer function coefficients), the system maintains high linearity and transmission accuracy across varying channel conditions while operating at high data rates.
Data Source
AI summary
A transmitter architecture includes an equalizer and a D/A converter, for high-speed transmission of data across a channel. The equalizer includes a two-tap MAC as part of an N-stage, two-way interleaved FIR filter. The two-tap MAC provides substantial power and area savings over conventional MAC-based FIR filter designs, and may be implemented in short or long communications channels. The D/A converter is decoupled from the equalizer. Its N-bit, binary-weighted driver includes matched unit current generation cells, all of which are fully utilized during each digital-to-analog conversion. The D/A converter remains unchanged, even when the characteristics of the equalizer are changed.