Shared ODI and DFE Sampler Architecture for Serial Receivers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional on-die instrumentation (ODI) circuits for high-speed serial data links are independent and often disturb the data path, making it complicated to implement ODI functionalities due to their independent samplers and the speculative decision feedback equalization (DFE) architecture.
Innovation Solution
The ODI/DFE multiplexing architecture shares select components, such as samplers and reference voltage generators, with the DFE adaptation circuitry, allowing ODI to monitor real data without disturbing the data path by using the DFE adaptation path as a replica of the clock data recovery (CDR) path, and employs time multiplexing between DFE and ODI modes to simplify design and improve signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional independent ODI circuits are used, then ODI functionality is provided, but the data path is disturbed and circuit area increases
Solution Approach 1:
The patent merges the ODI sampler with the DFE adaptation sampler into a single shared sampler circuit. This sampler is controlled by mode signals to switch between ODI sampling mode and DFE adaptation mode, eliminating the need for separate independent ODI circuits and reducing overall circuit area while maintaining both functionalities.
Solution Approach 2:
The shared sampler circuit is designed to perform multiple functions: it can operate as an ODI sampler for monitoring data eye diagrams, as a DFE adaptation sampler for equalization optimization, and can be controlled to switch between these modes. This multi-functional design reduces the number of components needed in the system.
2Measurement precision
If independent ODI samplers are used, then ODI measurement is enabled, but measurement accuracy decreases due to data path disturbance
Solution Approach 1:
The patent extracts the sampling function from the main data path by using the DFE adaptation path as a replica. The shared sampler samples from the DFE adaptation path rather than directly from the main data path, allowing ODI measurements to be taken without disturbing the critical data path while maintaining measurement accuracy through the replica path.
Solution Approach 2:
The DFE adaptation path serves as a replica or copy of the main CDR data path. By sampling from this replica path instead of the original data path, the system enables ODI measurements without introducing disturbance to the main data path, thus improving measurement accuracy while avoiding harmful disturbances.
3Adaptability or versatility
If separate ODI and DFE circuits are used, then both functionalities are independent, but design complexity increases
Solution Approach 1:
The patent combines the ODI and DFE circuits by sharing the sampler component between them. A single sampler is controlled by mode selection logic to perform either ODI sampling or DFE adaptation sampling as needed, reducing design complexity while maintaining the versatility and adaptability of both functionalities through controlled operation modes.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
One embodiment relates to a receiver (100) with both decision feedback equalization and on-die instrumentation. A clock data recovery loop (122, 123, 124) obtains a recovered clock signal from an input signal, and a first sampler (126), which is triggered by the recovered clock signal, generates a recovered data signal from the input signal. A phase interpolator (134) receives the recovered clock signal and generates a phase-interpolated clock signal. A second sampler (148) is triggered by the recovered clock signal in a decision feedback equalization mode and by the phase-interpolated clock signal in an on-die instrumentation mode. Other embodiments and features are also disclosed.