LET9120 RF MOSFET LDMOS Equivalent & Substitute Parts

Part Overview

The LET9120 is an RF MOSFET LDMOS transistor manufactured by STMicroelectronics, designed for RF applications operating at 860MHz with 150W output power and 18dB gain. The device is rated for 32V test voltage and 400mA test current in the M246 package.

This part is classified as Obsolete. Identification of equivalent and substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production requirements for applications utilizing this RF MOSFET technology.

Substiute Parts

LET9120

STMicroelectronicsIn Stock: 1085LET9120 Datasheet

Current PartRFQ

RF3L05150CB4

STMicroelectronicsIn Stock: 821RF3L05150CB4 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the LET9120 RF MOSFET LDMOS is determined by alignment of the following critical parameters:

Technology Match: Both the main part and substitute must utilize LDMOS (Laterally Diffused Metal-Oxide-Semiconductor) technology to ensure equivalent RF performance characteristics and thermal behavior.

Power Output Capability: The substitute part must deliver equivalent or greater output power (150W minimum) to maintain application performance requirements.

Frequency Compatibility: Operating frequency must support the target application band. The LET9120 operates at 860MHz; substitutes operating at higher frequencies (such as 1GHz) remain compatible for this application band.

Voltage Ratings: Test voltage and rated voltage parameters must be sufficient for the application circuit. The LET9120 specifies 32V test voltage and 80V rated voltage; substitutes with equal or higher ratings are acceptable.

Current Handling: Current rating and test current specifications must support the application load. The LET9120 specifies 18A current rating and 400mA test current.

Compliance and Certification: RoHS3 compliance, REACH status, and moisture sensitivity level must be maintained or improved to ensure regulatory and environmental compatibility.

Package Compatibility: Physical package type affects board layout and thermal management. Package differences require design review.

Parameter Comparison

Engineering Selection Recommendations

RF3L05150CB4 Substitution Basis:

The RF3L05150CB4 is identified as the manufacturer-recommended substitute for the obsolete LET9120. Both devices are manufactured by STMicroelectronics and utilize LDMOS technology. Both parts maintain identical 150W output power specifications and equivalent compliance certifications (ROHS3 Compliant, REACH Unaffected, MSL 1).

Product Status Advantage: The RF3L05150CB4 carries Active product status, ensuring continued availability and manufacturing support, whereas the LET9120 is Obsolete.

Frequency and Gain Enhancement: The RF3L05150CB4 operates at 1GHz with 23dB gain, compared to the LET9120 at 860MHz with 18dB gain. This represents improved RF performance characteristics suitable for higher-frequency applications while remaining compatible with 860MHz operation.

Voltage Rating Improvement: The RF3L05150CB4 specifies 90V rated voltage compared to the LET9120 at 80V, providing enhanced voltage margin.

Package Consideration: The RF3L05150CB4 utilizes the LBB package with Chassis Mount configuration, whereas the LET9120 uses the M246 package. Package transition requires PCB layout and thermal management review.

Compliance Maintenance: Both parts maintain equivalent regulatory compliance, ensuring no degradation in environmental or safety certifications.

Frequently Asked Questions (FAQ)

Q: Why is the LET9120 classified as Obsolete?

A: The LET9120 has reached end-of-life status in the STMicroelectronics product portfolio. Obsolete classification indicates the manufacturer no longer produces this part. The RF3L05150CB4 represents the active-status successor technology.

Q: Can the RF3L05150CB4 directly replace the LET9120 without design modifications?

A: Both parts deliver 150W output power and utilize LDMOS technology. However, the package transition from M246 to LBB requires PCB layout revision. The higher operating frequency (1GHz vs. 860MHz) and improved gain (23dB vs. 18dB) are compatible with 860MHz applications but may require impedance matching network adjustment.

Q: What are the key electrical differences between these parts?

A: The RF3L05150CB4 operates at higher frequency (1GHz vs. 860MHz) with higher gain (23dB vs. 18dB). Test voltage is lower (28V vs. 32V), but rated voltage is higher (90V vs. 80V). Current rating differs (2.5A vs. 18A), and test current is higher (500mA vs. 400mA). Output power remains equivalent at 150W.

Q: Are both parts RoHS3 compliant?

A: Yes. Both the LET9120 and RF3L05150CB4 are ROHS3 Compliant with MSL 1 (Unlimited) moisture sensitivity level and REACH Unaffected status.

Q: What does the package designation change from M246 to LBB mean?

A: M246 and LBB represent different physical package types. The LBB package includes Chassis Mount configuration. This change affects PCB footprint, mounting method, and thermal interface design. Board layout and mechanical assembly must be updated accordingly.

Q: Is the RF3L05150CB4 available in inventory?

A: The RF3L05150CB4 is listed as Active product status with 787 pieces in new original stock, available in Tape & Reel (TR) packaging format.

Q: Can the RF3L05150CB4 operate at 860MHz?

A: Yes. The RF3L05150CB4 is rated for 1GHz operation, which encompasses the 860MHz frequency band. The device is compatible with 860MHz applications.

Q: What compliance certifications apply to both parts?

A: Both parts carry ROHS3 Compliant status, REACH Unaffected designation, and EAR99 ECCN classification. Moisture sensitivity level is MSL 1 (Unlimited) for both devices.