Op-Amp Similarity Calculator Skill

Guidance for working with OpAmpSimilarityCalculator in the lib-electronic-components library.

For metadata-driven similarity architecture, see /similarity-metadata:

•SpecImportance levels (CRITICAL, HIGH, MEDIUM, LOW, OPTIONAL)
•ToleranceRule types (exactMatch, percentageTolerance, minimumRequired, etc.)
•SimilarityProfile contexts (DESIGN_PHASE, REPLACEMENT, COST_OPTIMIZATION, etc.)
•Calculator integration patterns and gotchas

Overview

The OpAmpSimilarityCalculator compares operational amplifiers based on:

•Equivalent families - Known interchangeable parts
•Channel count - Single, dual, quad configurations
•Characteristics - Bandwidth, slew rate, input type

Applicable Types

java

ComponentType.OPAMP
ComponentType.OPAMP_TI
ComponentType.OPAMP_ANALOG_DEVICES
ComponentType.OPAMP_ST
// Any type starting with "OPAMP_"

Similarity Thresholds

java

HIGH_SIMILARITY = 0.9;   // Equivalent parts
MEDIUM_SIMILARITY = 0.7; // Same family, compatible
LOW_SIMILARITY = 0.3;    // Different family

Equivalent Families

Dual Op-Amps (2 channels)

Family	Members
LM358 family	LM358, LM358A, LM358B, MC1458, RC1458
TL072 family	TL072, TL072A, TL072B, TL072C
NE5532 family	NE5532, NE5532A, SA5532, SE5532

Quad Op-Amps (4 channels)

Family	Members
LM324 family	LM324, LM324A, LM324N, MC3403, RC3403
TL074 family	TL074, TL074A, TL074B, TL074C

Single Op-Amps

Family	Members
LM741 family	LM741, UA741, MC741, RC741

Channel Count Rules

The calculator considers channel count when comparing:

Comparison	Result
LM358 (dual) vs MC1458 (dual)	0.9 (equivalent)
LM358 (dual) vs LM324 (quad)	0.7 (same family, different count)
LM358 (dual) vs LM741 (single)	0.7 (same technology, different count)

Package Suffix Handling

Common suffixes are normalized:

•N, P - DIP packages
•D, DR - SOIC packages
•PW, PWR - TSSOP packages
•A, B - Grade variants

java

calculator.calculateSimilarity("LM358N", "LM358D", registry);
// Returns 0.9 (same op-amp, different package)

Test Examples

java

// Equivalent dual op-amps
calculator.calculateSimilarity("LM358", "MC1458", registry);
// Returns 0.9

// Same family, different grades
calculator.calculateSimilarity("LM324", "LM324A", registry);
// Returns 0.9

// Dual vs quad (different channel count)
calculator.calculateSimilarity("TL072", "TL074", registry);
// Returns 0.7

// Non-op-amp parts
calculator.calculateSimilarity("IRF530", "2N2222", registry);
// Returns 0.0

Key Characteristics

The calculator may also consider:

•GBW (Gain-Bandwidth Product)
•Slew Rate
•Input Type (JFET vs BJT)
•Rail-to-Rail capability

Metadata-Driven Implementation (January 2026)

Status: ✅ Converted (PR #116)

The OpAmpSimilarityCalculator now uses a metadata-driven approach with spec-based comparison.

Specs Compared

Spec	Importance	Tolerance Rule	Description
configuration	CRITICAL	exactMatch	Single, dual, quad channel count
family	HIGH	exactMatch	LM358, TL072, NE5532, etc.
package	MEDIUM	exactMatch	DIP, SOIC, TSSOP, etc.

Implementation Details

java

@Override
public double calculateSimilarity(String mpn1, String mpn2, PatternRegistry registry) {
    // Try metadata-driven approach first
    Optional<ComponentTypeMetadata> metadataOpt = metadataRegistry.getMetadata(ComponentType.OPAMP);
    if (metadataOpt.isPresent()) {
        return calculateMetadataDrivenSimilarity(mpn1, mpn2, metadataOpt.get());
    }
    // Fallback to legacy family-based approach
    return calculateFamilyBasedSimilarity(mpn1, mpn2);
}

Key Features:

•Short-circuit check: Different configurations (single vs dual vs quad) return LOW_SIMILARITY immediately
•Family boost: Known equivalent families (LM358 ≈ MC1458) boost similarity to HIGH_SIMILARITY
•Weighted scoring: totalScore / maxPossibleScore formula for precise comparison
•Backward compatible: Falls back to legacy logic if metadata not available

Spec Extraction Methods

java

// Extract configuration from MPN
private String extractConfiguration(String mpn) {
    if (matchesDualOpAmp(mpn)) return "dual";
    if (matchesQuadOpAmp(mpn)) return "quad";
    if (matchesSingleOpAmp(mpn)) return "single";
    return "";
}

// Extract family from MPN
private String extractFamily(String mpn) {
    // Returns: LM358, LM324, TL072, TL074, NE5532, etc.
}

// Extract package from MPN
private String extractPackageCode(String mpn) {
    // Returns: N, D, DR, PW, P, etc.
}

Behavior Changes

Before (Legacy): Hardcoded equivalent family checks After (Metadata): Configurable specs with weighted importance

Comparison	Legacy Result	Metadata Result	Notes
LM358 vs MC1458	0.9	1.0	Exact configuration + family match
LM358N vs LM358D	0.9	0.958	Same op-amp, different package
LM358 vs LM324	0.7	LOW_SIMILARITY	Short-circuit on configuration mismatch
TL072 vs TL074	0.7	LOW_SIMILARITY	Different channel count

Why more accurate: Metadata approach clearly separates configuration (CRITICAL) from package (MEDIUM), providing more precise scoring.

Learnings & Quirks

Naming Conventions

•LM prefix: National Semiconductor (now TI)
•MC prefix: Motorola (now ON Semi)
•TL prefix: TI JFET-input
•NE/SA/SE prefix: Signetics (now TI)
•UA/RC prefix: Various second sources

Family Relationships

•LM358/LM324: Same die, 358 is dual, 324 is quad
•TL072/TL074: JFET-input, 072 is dual, 074 is quad
•NE5532/NE5534: 5532 is dual, 5534 is single (lower noise)

Cross-Manufacturer Equivalence

•LM358 ≈ MC1458 ≈ RC1458 (all dual, general purpose)
•LM324 ≈ MC3403 ≈ RC3403 (all quad, general purpose)