Mixed-Signal Interface With Single-Pole Gain Stages for 12 Gb/s Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional interfaces between current mode logic (CML) and complementary metal oxide semiconductor (CMOS) logic families have limited bandwidth due to their two-pole architecture, restricting high-speed signal conversion to approximately 6 or 7 GB/s and requiring additional power-consuming bias circuits.
Innovation Solution
A mixed-signal interface with a single-pole architecture gain stage, utilizing a PMOS and NMOS device configuration and a feedback resistor to self-bias and enhance gain, while maintaining high-speed operation up to 12 Gb/s without the need for additional bias circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a two-stage amplifier with two-pole architecture is used for signal conversion between CML and CMOS logic families, then the interface can provide rail-to-rail operation with amplification, but the bandwidth is limited to approximately 6 or 7 GB/s
Solution Approach 1:
The patent divides the signal conversion function into two independent single-pole amplifier stages: one dedicated to CML-to-CMOS conversion and another for CMOS-to-CML conversion. Each stage operates independently with its own gain control, eliminating the bandwidth limitations of a two-pole architecture while maintaining the necessary signal level conversion capabilities.
Solution Approach 2:
The patent implements dynamic gain control in each amplifier stage through separately controllable gain elements. This allows the system to adaptively adjust the amplification level in each stage based on input signal conditions, optimizing bandwidth and signal integrity without requiring a fixed two-pole architecture.
2Use of energy by moving object
If a conventional two-pole architecture interface is used, then signal conversion between logic families is achieved, but additional bias circuits are required which consume more power and area
Solution Approach 1:
The patent extracts and eliminates the need for separate bias circuits by integrating the biasing function directly into the amplifier stages through feedback mechanisms. Each single-pole amplifier stage is designed to self-bias, removing the additional power-consuming bias circuitry required in conventional two-pole architectures.
Solution Approach 2:
The amplifier stages are designed with feedback networks that automatically establish and maintain the required operating points without external bias circuits. The circuits self-regulate their bias conditions based on signal levels, eliminating the need for separate bias generation components and reducing overall power consumption.
3Speed
If CML logic is used for high-speed operation, then bandwidth is improved, but power consumption and area increase compared to CMOS logic
Solution Approach 1:
The patent merges the advantages of both CML and CMOS logic families by using CML for high-speed signal reception and conversion to CMOS for low-power processing. The interface circuitry enables seamless signal level translation between the two logic families, allowing the system to leverage CML's speed where needed and CMOS's power efficiency for the majority of operations.
Solution Approach 2:
The patent applies different logic family characteristics to different parts of the system: CML is used locally in the interface stage where high-speed signal reception is critical, while CMOS is used throughout the rest of the system where power consumption is the primary concern. This localized application of logic family strengths optimizes overall system performance.
Data Source
AI summary
An apparatus is disclosed for converting signals from one digital integrated circuit family to be compatible with another digital integrated circuit family. The apparatus includes a primary interface and a secondary interface to convert a differential output signal from one digital integrated circuit family for use as an input signal by another digital integrated circuit family. The primary and secondary interfaces include gain stages that are configurable to provide rail to rail voltage swings and are characterized as having single pole architectures. The secondary interface may be unterminated such that a substantially equal load is presented to both components of the differential output signal.