Memory system having incorrupted strobe signals
View Patent ↗A memory system circuit and method therefor are disclosed. The circuit is adapted to detect a transition in a data timing signal from an indeterminate logic level to a selected one of a high logic level and a low logic level. The circuit includes a comparator having a first input, a second input and an output. The first and second inputs receive the data timing signal and a reference voltage respectively. The output changes logic levels in response to a change in polarity of a voltage difference between the voltage of the timing signal and the reference voltage. The reference voltage is sufficiently closer to the selected one of the logic levels as compared to the other of the logic levels so as to at least substantially prevent potential false positive detections.
1. A method for preamble detection within a microelectronics system, the method comprising:
receiving a clock signal of the type in which a series of regular pulses in voltage level of said clock signal are preceded by a preamble period having a beginning and an end, a transition in said clock signal from an indeterminate logic level to a selected one of a high logic level and a low logic level occurring at said beginning of the preamble period;
receiving a complement of said clock signal, a transition in said complement of the clock signal from said indeterminate logic level to the other of the logic levels occurring at said beginning of the preamble period;
generating indication that said beginning of the preamble period has occurred by:
i) detecting said transition in the clock signal based on when the voltage level of the clock signal crosses through a first threshold of a voltage range; and
ii) detecting said transition in said complement of the clock signal based on when the voltage level of said complement of the clock signal crosses through a second threshold of said voltage range.
2. The method as claimed in claim 1 , wherein said clock signal is a data strobe clock (DQS) signal and said complement of the clock signal is a complement of said DQS signal.
3. The method as claimed in claim 2 , wherein the selected one of the logic levels is said low logic level, and the other of the logic levels is said high logic level.
4. The method as claimed in claim 1 , wherein the detecting said transition in the clock signal is carried out by a comparator having one of its inputs receiving a reference voltage at said first threshold.
5. The method as claimed in claim 4 , wherein said one of the inputs is an inverting input, and said first threshold is higher than said second threshold.
6. The method as claimed in claim 1 , wherein the detecting said transition in said complement of the clock signal is carried out by a comparator having one of its inputs receiving a reference voltage at second threshold.
7. The method as claimed in claim 6 , wherein said one of the inputs is an inverting input, and said first threshold is higher than said second threshold.