Memory Read Signal Trimming via Frequency Division
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Solution Overview
Problem
Integrated circuits face challenges in accurately measuring and trimming the timing of read signals with short durations due to large capacitances of output pads, which hinder precise signal feature measurement and proper read operations.
Innovation Solution
An integrated circuit with a read signal generator and frequency divider that generates oscillating signals with adjustable periods, allowing for accurate measurement of short signal features through frequency division, enabling trimming of signal features to fit within selected tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frequency of read clock signals is increased to improve read operation speed, then the number of read operations per second increases, but the time window for performing individual read operations decreases
Solution Approach 1:
The patent segments the read operation timing into distinct phases (precharge phase and evaluation phase) with specific timing windows. By dividing the read operation into manageable time segments and generating corresponding read signals (precharge signal and evaluation signal) for each phase, the system can accurately control timing even at high clock frequencies
Solution Approach 2:
The patent implements preliminary action by generating precharge signals before evaluation signals to prepare the sense amplifiers in advance. The precharge phase charges the bitlines before the evaluation phase reads the data, ensuring that the sense amplifiers are properly prepared and biased before the actual read operation begins
2Ease of operation
If output pads with large area are used for testing, then ease of connection is improved, but measurement precision of short signal features deteriorates due to large capacitance charging and discharging times
Solution Approach 1:
The patent introduces an intermediary measurement approach by using the output pad to measure the period of oscillating signals and their frequency-divided versions rather than directly measuring short-duration read signal features. The frequency divider acts as a mediator that transforms the measurement task into one suitable for pads with large capacitance
Solution Approach 2:
The patent changes the measurement parameter from direct time-domain measurement of short signal features to frequency-domain measurement of oscillating signals. By measuring the period and frequency of oscillating signals (which are longer duration) and using these measurements to infer the timing characteristics of the original read signals, the system overcomes the limitation of pad capacitance
Data Source
AI summary
A read signal generator generates read signals to control read operations of a memory array. The read signal generator can be selectively controlled to generate an oscillating signal having a period that corresponds to a feature one of the read signals. The oscillating signal is passed to a frequency divider that divides the oscillating signal and provides the divided oscillating signal to an output pad. The frequency of the oscillating signal can be measured at the output pad. The frequency of the oscillating signal, and the duration of the read signal feature can be calculated from the frequency of the oscillating signal. The read signal feature can then be adjusted if needed.