Synchronous Delay Circuit for DDR2 SDRAM Write Timing
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Solution Overview
Problem
In semiconductor memory apparatuses like DDR2 SDRAM, the increased length of global input/output (GIO) lines leads to parasitic RC delay times, causing the bank write enable signal to be delayed, potentially resulting in data transmission errors due to environmental and process variable influences, especially at low voltages and high frequencies.
Innovation Solution
A semiconductor memory apparatus with a synchronous delay circuit unit that generates a bank write enable signal in synchronization with the falling edge of the column active signal, using a pulse generator with a resistor, capacitor, and inverters to ensure accurate timing of data transmission, reducing the impact of GIO line length and environmental factors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the GIO line length is increased to accommodate higher memory capacity (e.g., 1G byte DDR2 SDRAM), then the memory capacity is improved, but parasitic RC delay time increases causing data transmission errors
Solution Approach 1:
A synchronous delay circuit unit is introduced as an intermediary component between the GIO line and the write driver. This delay circuit generates a bank write enable signal with precisely controlled delay timing, mediating the timing mismatch caused by parasitic RC delays in the extended GIO line, thereby ensuring accurate data latching without compromising transmission integrity
Solution Approach 2:
The invention changes the timing parameters of the bank write enable signal by introducing a controllable delay circuit. The delay amount is specifically designed to compensate for the parasitic RC delay caused by the extended GIO line length, adjusting the signal timing parameter to maintain synchronization between data arrival and write enable activation
2Quantity of substance
If the GIO line length is increased, then memory capacity is improved, but timing accuracy of the bank write enable signal deteriorates
Solution Approach 1:
The synchronous delay circuit acts as a timing intermediary that receives the column active signal and generates the bank write enable signal with precisely controlled delay. This mediator ensures that despite variations in GIO line length, the timing accuracy of the bank write enable signal is maintained by adding a fixed, calibrated delay amount
Solution Approach 2:
The delay circuit performs preliminary timing adjustment on the bank write enable signal before it reaches the write driver. By pre-calculating and applying the necessary delay amount based on the expected GIO line characteristics, the system ensures accurate timing alignment is established in advance, compensating for the extended line length effects
3Device complexity
If general delay members (inverters and RC elements) are used to delay the bank write enable signal, then delay functionality is achieved, but the delay time varies due to environmental factors (voltage, temperature, frequency)
Solution Approach 1:
The synchronous delay circuit incorporates feedback mechanisms that monitor the actual timing relationship between the column active signal and the data signal, and dynamically adjust the delay amount accordingly. This feedback control compensates for environmental variations, maintaining stable delay time despite changes in voltage, temperature, or frequency conditions
Solution Approach 2:
The delay circuit is designed to be dynamic rather than static, allowing the delay amount to be adjusted based on operating conditions. The circuit can adaptively change its delay characteristics in response to environmental factors, ensuring consistent timing performance across varying voltage, temperature, and frequency environments
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures the bank write enable signal is generated at the correct timing, preventing data errors and maintaining data transmission accuracy across varying conditions, even with longer GIO lines, by adjusting the delay time to match the pulse width of the column active signal.
Implementation Method 1
a circuit member that includes a plurality of inverters and RC elements
Implementation Method 2
a circuit member that includes a plurality of inverters and RC elements
Data Source
AI summary
A semiconductor memory apparatus includes a write driver that receives data transmitted through an input/output line, and a synchronous delay circuit unit that generates an enable signal so as to allow the data transmitted through the input/output line to be supplied to the write driver.