DFE Bias Voltage Circuit With PVT Drift Compensation
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Solution Overview
Problem
Variations in process, voltage, and temperature (PVT) characteristics cause undesired drift in bias voltages used by memory devices, compromising the decision-making performance of decision feedback equalizer (DFE) circuits, leading to increased data errors due to intersymbol interference.
Innovation Solution
Implement voltage generation circuitry with temperature correction and supply correction mechanisms to generate adjusted reference currents, which are applied to replica NMOS transistors and resistors to stabilize high and low bias voltages, mitigating PVT-induced variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the operational rate of memory devices is increased, then productivity is improved, but data errors due to distortion and intersymbol interference increase
Solution Approach 1:
A decision feedback equalizer (DFE) circuit is implemented to compensate for channel distortion and intersymbol interference. The DFE uses feedback from previously decided symbols to cancel out interference in current symbol decisions, thereby maintaining data accuracy at higher operational rates.
Solution Approach 2:
Offset voltages supplied to the DFE circuit are adjusted and optimized to compensate for channel effects. By dynamically changing the offset voltage parameters, the system can adapt to different channel conditions and maintain reliable data reception at increased speeds.
2Measurement precision
If bias voltage is supplied to DFE circuit for decision making, then decision-making performance is improved, but PVT variations cause voltage drift that compromises performance
Solution Approach 1:
Temperature correction circuitry and supply correction circuitry are implemented to monitor and compensate for PVT variations. These circuits use feedback mechanisms to detect voltage drift and temperature changes, then adjust the bias voltages accordingly to maintain stable DFE operation.
Solution Approach 2:
Temperature correction circuitry and supply correction circuitry act as intermediary components between the power supply and the DFE circuit. These intermediaries condition and stabilize the bias voltages before they reach the DFE, filtering out PVT-induced variations.
3Stability of the object's composition
If temperature correction and supply correction mechanisms are added to stabilize bias voltages, then voltage stability is improved, but device complexity increases
Solution Approach 1:
Temperature correction circuitry and supply correction circuitry are integrated into the voltage generation circuitry. By merging these correction functions with the existing voltage generation architecture, the patent reduces overall system complexity compared to having separate standalone correction circuits.
Solution Approach 2:
The voltage generation circuitry is designed to perform multiple functions: generating bias voltages, correcting temperature variations, and compensating for supply variations. This multi-functionality eliminates the need for separate dedicated circuits for each function, thereby reducing device complexity.
Data Source
AI summary
A memory device includes a resistor string digital to analog convertor (DAC) configured to supply one or more offset voltages to a decision feedback equalizer (DFE) based on high and low bias voltages. The memory device also includes bias voltage generation circuitry configured to generate a reference current based on an offset voltage range trim, to generate a first correction current based on a detected temperature change, generate a second correction current based on a supplied voltage, the reference voltage of the memory device, and a supply correction trim, to generate an adjusted reference current based on the reference current, the first correction current, and the second correction current, to generate the high bias voltage based on the adjusted reference current, to generate the low bias voltage based on the reference current, and to supply the high bias voltage and the low bias voltage to the resistor string DAC.