STMicroelectronics LET9070CB

Overview

LET9070CB from STMicroelectronics is a common-source N-channel enhancement-mode lateral MOSFET RF power transistor designed for broadband base station amplifiers up to 1.0 GHz. It delivers 70 W output power at 945 MHz with 17 dB gain and 60–65% drain efficiency at 28 V, housed in a BeO-free M243 ceramic package with 1.0 °C/W junction-to-case thermal resistance.

For engineers reviewing the LET9070CB datasheet, LET9070CB pinout, LET9070CB application, or LET9070CB equivalent, this device is selected for high-linearity RF final-stage amplification in commercial and industrial infrastructure where thermal stability, load mismatch tolerance (20:1 VSWR), and DC bias robustness are critical design requirements.

Technical Context

The LET9070CB operates in common-source configuration with fixed gate bias (V_GS(Q) = 2.0–5.0 V) and exhibits low input impedance (Z_IN ≈ 0.59 Ω – j0.2 Ω at 945 MHz) and optimized load impedance (Z_LOAD ≈ 1.86 Ω + j0.08 Ω). Its lateral MOSFET architecture enables stable gain flatness across 100–1000 MHz and supports broadband matching without external feedback networks.

Thermal performance is defined by R_th(JC) = 1.0 °C/W and T_J(max) = 200 °C, enabling continuous-wave operation at P_DISS = 130 W when case temperature is maintained at 70 °C. The device sustains 20:1 VSWR under full power (100 W at 35 V) without degradation, confirming ruggedness for antenna mismatch scenarios in deployed systems.

Key Specifications

Pinout & Package

The LET9070CB is housed in an M243 (.230 × .360 inch) 3-terminal ceramic-metal hermetic package with flange, rated for high-power RF operation and RoHS-compliant per 2002/95/EC. The flanged base provides low-inductance, low-thermal-resistance mounting to heatsinks.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF power transistor applications.

Compared with MRF15810HR5 and PD85003-E, the LET9070CB uniquely balances 70 W output, 17 dB gain, and 1.0 °C/W thermal resistance in a BeO-free package-making it optimal for cost-sensitive, thermally constrained macrocell base station PAs requiring field-proven ruggedness.

Availability

LET9070CB is available at Aetrix Electronics and suitable for macrocell base station amplifiers, industrial RF heating systems, public safety repeaters, and broadcast auxiliary transmitters requiring stable component supply and long-lifecycle support.

Supply support for LET9070CB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, power, and analog/mixed-signal technologies with manufacturing in Europe and Asia.

The LET9070CB belongs to ST's LdmoST family of lateral MOSFETs, engineered specifically for high-efficiency, high-linearity RF power amplification in commercial and industrial infrastructure operating up to 1 GHz.

FAQ

What is the recommended gate bias voltage for linear operation?

The LET9070CB achieves optimal linearity and efficiency at V_GS(Q) = 3.5–4.5 V with I_DQ = 400 mA. This bias point ensures stable Class AB operation across temperature, minimizes gain compression, and maintains ACLR below −42 dBc in 2-carrier UMTS testing per the datasheet's Figure 6 and Table 4.

Can LET9070CB operate reliably at 32 V supply?

Yes-the device is rated for V(BR)DSS = 80 V and demonstrates stable 70 W output and 17 dB gain at 32 V in Figure 8. However, drain current must be limited to ≤12 A and case temperature held ≤70 °C to maintain P_DISS ≤130 W and prevent thermal runaway per absolute maximum ratings in Table 2.

Is external ESD protection required in PCB layout?

No-LET9070CB integrates bidirectional ESD protection on all pins rated to ±1 kV HBM. Layout best practices still apply: keep gate traces short, use ground vias near gate pad, and avoid floating metal near source/drain; no external TVS diodes or series resistors are needed for ESD robustness.

What is the minimum recommended heatsink thermal resistance?

To maintain T_J ≤200 °C at full 130 W dissipation with T_CASE = 70 °C, total thermal resistance (R_th(JC) + R_th(CS) + R_th(SA)) must be ≤1.3 °C/W. Given R_th(JC) = 1.0 °C/W, the heatsink (including interface material) must contribute ≤0.3 °C/W-achievable with forced-air-cooled copper baseplates or liquid cold plates.