SerDes Loopback Sense Amplifier Without Multiplexer Bandwidth Loss
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing loopback techniques in Serializer/Deserializer (SerDes) devices are inadequate, leading to bandwidth degradation and increased capacitance due to the use of multiplexers, which are necessary for isolating receiver inputs and coupling transmitter outputs, thereby reducing receiver performance.
Innovation Solution
The integration of a sense amplifier with direct connections to high-frequency signals from an equalizer and selectively coupled inputs from a DAC or loopback signals, along with switches and filters, allows for efficient loopback operation without multiplexers, utilizing an offset correction circuit to prevent additional bandwidth loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiplexers are used to isolate receiver inputs and couple transmitter outputs for loopback function, then loopback capability is achieved, but receiver bandwidth is reduced and capacitance is increased
Solution Approach 1:
The patent extracts and removes the multiplexer component from the loopback signal path. Instead of using a multiplexer to couple the transmitter output to the receiver input, the invention creates a direct connection path that bypasses the multiplexer, thereby eliminating the capacitance and resistance introduced by the multiplexer while preserving the loopback capability.
Solution Approach 2:
The patent segments the receiver input into two separate paths: one path for normal data reception and another path for loopback signals. This is achieved by providing separate input terminals and using switches to selectively connect the loopback signal to the receiver input without interfering with the normal data path, thus avoiding the need for a multiplexer.
2Adaptability or versatility
If multiplexers are used to implement loopback function, then signal routing is achieved, but additional capacitance and resistance are introduced
Solution Approach 1:
The patent extracts the multiplexer from the signal path and replaces it with a direct connection. The loopback signal is coupled directly to the receiver input through a switch and filtering capacitor, eliminating the additional capacitance and resistance that would be introduced by a multiplexer while maintaining the signal routing capability.
3Reliability
If switches and filtering capacitors are used to couple loopback signals, then multiplexer-induced degradation is eliminated, but circuit complexity increases
Solution Approach 1:
The patent makes the switch and filtering capacitor serve multiple functions: they are used both for coupling loopback signals and for normal data reception operations. The switch selectively connects either the external signal or the loopback signal to the receiver input, while the filtering capacitor handles both loopback signal filtering and normal data signal conditioning, thereby reducing overall circuit complexity despite the added components.
Data Source
AI summary
The present invention is directed to integrated circuits. In a specific embodiment, high frequency signals from an equalizer is directly connected to a first pair of inputs of a sense amplifier. The sense amplifier also has a second pair of inputs, which can be selectively coupled to output signals from a DAC or high frequency loopback signals. There are other embodiments as well.