Fuse State Detection Circuit Offset Currents
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Solution Overview
Problem
Existing fuse state detection circuits in chips lack the necessary flexibility and sensitivity, as single-sided circuits are not sensitive enough and differential circuits have an indeterminate default state, making them unsuitable for all applications.
Innovation Solution
A fuse state detection circuit with two current sources and a voltage difference detection device, where identical fuses are connected in series in both signal and reference legs, and the current sources are configured to provide offset currents, allowing the trip point to be placed between un-blown and minimum blown resistance, enabling flexible and sensitive detection without pre-blowing fuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single-sided fuse state detection circuit is used, then the circuit structure is simple, but the detection sensitivity is insufficient
Solution Approach 1:
The detection circuit is segmented into two separate legs: a signal leg containing the fuse to be tested and a reference leg containing an un-blown fuse. This segmentation allows independent optimization of each path, enabling the reference leg to provide a stable baseline while the signal leg undergoes fuse blowing, thereby improving detection sensitivity without excessive complexity.
Solution Approach 2:
Offset currents are applied to the signal and reference legs, creating different current levels (I_signal ≠ I_reference). This parameter change allows the trip point to be positioned between un-blown and minimum blown resistance values, enhancing the detection sensitivity by creating a larger voltage difference signal when fuses are blown.
2Measurement precision
If a differential fuse state detection circuit is used, then the detection sensitivity is improved, but the default state becomes indeterminate
Solution Approach 1:
Different qualities are assigned to different parts of the circuit: the reference leg maintains a fixed, un-blown state providing a stable reference, while the signal leg allows fuses to be blown on demand. This local differentiation ensures the circuit defaults to a known state (reference leg intact) while still providing high sensitivity through differential measurement.
Solution Approach 2:
The reference fuse is preliminarily configured to remain un-blown and intact before detection occurs. This preliminary action establishes a known, stable reference state that the circuit defaults to, providing determinism and flexibility while the signal leg fuses can be selectively blown for testing.
3Measurement precision
If multiple fuses are connected in series in each leg, then the detectable range for blown fuses is increased, but the circuit complexity increases
Solution Approach 1:
Multiple fuses are segmented and connected in series within each leg (signal and reference). This segmentation approach increases the total resistance change when fuses are blown, thereby expanding the detectable range and improving sensitivity. The modular series connection maintains relative structural simplicity while achieving enhanced detection capability.
4Measurement precision
If offset currents are provided to each leg, then the trip point can be placed between un-blown and minimum blown resistance, but the current source configuration becomes more complex
Solution Approach 1:
Offset currents with different magnitudes are applied to the signal and reference legs by configuring the current sources accordingly. This parameter change enables precise positioning of the trip point between un-blown and minimum blown resistance values, improving measurement precision. While the current source configuration is somewhat complex, it provides deterministic trip point control that simpler configurations cannot achieve.
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 configuration increases detectable range for blown fuses, providing greater sensitivity than both single-sided and differential detection techniques while maintaining flexibility, allowing for accurate detection without pre-blown fuses and reducing operational current.
Implementation Method 1
a voltage difference detection device with two inputs and identical signal and reference legs
Implementation Method 2
The signal and reference legs of the circuit are each electrically connected between a corresponding one of the current sources and a corresponding one of the inputs to the voltage difference detection device
Data Source
AI summary
Disclosed are embodiments of an apparatus incorporating a detection circuit adapted for determining the state of selected fuses and a programming circuit for blowing selected fuses on demand. Also, disclosed are embodiments of an associated method. The detection circuit comprises a plurality of fuses in identical signal and reference legs in order to increase the signal margin for detecting blown fuses and/or current sources configured to pass offset currents through the signal and reference legs in order to set the trip point for detecting blown fuses between the un-blown and the minimum blown resistances. Thus, the invention provides the flexibility of single-sided fuse state detection devices with even greater sensitivity than both single-sided and differential fuse state detection device.