Receiver Gain and Target Amplitude Training for Lower BER
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Solution Overview
Problem
Optical communication systems face signal impairments such as attenuation, distortion, and noise, leading to increased Bit Error Rate (BER), particularly in high-speed systems using multi-level pulse-amplitude modulation (PAM) signals, due to variations in input signal amplitude and temperature, affecting the performance of receivers.
Innovation Solution
An enhanced receiver training method tunes the static gain of static gain amplifiers and sets a target amplitude for dynamic gain amplifiers by disabling dynamic gain adjustment during a training phase, determining optimal static gain and amplitude settings to achieve a maximum link performance metric, thereby reducing BER and increasing thermal headroom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dynamic gain adjustment is enabled to compensate for signal amplitude variations, then receiver performance under varying input conditions improves, but static gain tuning becomes inaccurate and thermal headroom decreases
Solution Approach 1:
The patent applies preliminary action by performing static gain tuning during a training phase before normal operation begins. The dynamic gain adjustment is disabled during this training phase, allowing the static gain to be accurately tuned to a target amplitude without interference from dynamic variations. This preliminary configuration ensures reliable baseline performance before adaptability is activated.
Solution Approach 2:
The patent implements dynamics by separating the tuning phase from the operation phase. During training, the system is static (dynamic gain disabled) for accurate tuning. During normal operation, the system becomes dynamic (dynamic gain enabled) to adapt to varying input conditions. This temporal separation allows both static tuning accuracy and dynamic adaptability to coexist.
2Reliability
If static gain is tuned to maximize link performance, then BER reduces, but thermal headroom and capacity to withstand temperature variations decreases
Solution Approach 1:
The patent changes the parameter being optimized from purely maximizing link performance to a balanced configuration. By tuning the static gain to a target amplitude that accounts for thermal variations rather than maximizing immediate performance, the system achieves acceptable BER while preserving thermal headroom. This parameter adjustment allows the system to withstand temperature variations better.
Solution Approach 2:
The patent applies beforehand cushioning by setting the static gain target amplitude to account for future thermal variations. Instead of optimizing for current peak performance, the tuning anticipates temperature changes and sets a conservative target that provides a cushion against thermal effects. This ensures the system maintains performance under temperature variations without requiring excessive gain.
3Reliability
If target amplitude is set high to maintain signal quality, then BER reduces, but dynamic range for compensation and thermal headroom decreases
Solution Approach 1:
The patent applies partial action by setting the target amplitude to a moderate level rather than maximizing it. The static gain is tuned to achieve sufficient signal quality without over-amplifying. This partial amplification leaves headroom in the dynamic range, allowing the dynamic gain to compensate for variations without clipping or distortion, thus maintaining both signal quality and adaptability.
Data Source
AI summary
Examples described herein relate to a receiver training method. To configure a static gain for at least one static gain amplifier and a target amplitude for a dynamic gain amplifier, a dynamic gain adjustment is disabled and the dynamic gain amplifier is configured to apply a predetermined fixed gain to the static gain amplified signal to generate a test signal. Furthermore, an effective static gain magnitude for at least one static gain amplifier and an effective amplitude for the test signal are determined based on a link performance metric. The static gain is set to the effective static gain magnitude, and a target amplitude for the dynamic gain amplifier is set to the effective amplitude. Then, the dynamic gain adjustment may be enabled to maintain an amplitude of a dynamic gain amplified signal at an output of the dynamic gain amplifier at the target amplitude by varying the dynamic gain.