Analog Devices Inc. LT5579IUH#TRPBF

Overview

LT5579IUH#TRPBF from Analog Devices (acquired Linear Technology) is a high-linearity, single-ended upconverting mixer IC optimized for RF transmitter signal chains in 1.5GHz–3.8GHz bands. It delivers +27.3dBm OIP3, –158dBm/Hz noise floor at –5dBm RF output, and 2.6dB conversion gain at 2.14GHz with only –1dBm LO drive on a single 3.3V supply. It serves as the core frequency translation stage in W-CDMA/LTE base station transmitters.

For engineers reviewing the LT5579IUH#TRPBF datasheet, LT5579IUH#TRPBF pinout, LT5579IUH#TRPBF application, or LT5579IUH#TRPBF equivalent, key selection criteria include its wide RF bandwidth (900–3900MHz), low LO leakage (–35dBm typical), differential IF input interface, and QFN24 thermal-performance requirements - all critical for high-dynamic-range wireless infrastructure designs.

Technical Context

The LT5579IUH#TRPBF integrates a high-gain LO buffer driving a double-balanced active mixer core with internal baluns, enabling single-ended LO input and RF output while maintaining differential IF signaling. Its architecture minimizes LO-to-RF feedthrough via balanced topology and internal series DC blocking on LO pin 22.

It operates with internally regulated 570mV common-mode voltage on IF+ and IF– pins, requiring external 11Ω resistors and 40nH inductors to set ~50mA per side bias current. The exposed pad (pin 25) serves as both electrical ground and primary thermal path, mandating PCB soldering to a low-impedance RF ground plane.

Key Specifications

Pinout & Package

LT5579IUH#TRPBF uses a 24-lead, 5mm × 5mm plastic QFN package (UH) with exposed thermal pad (pin 25). The package requires soldering of the exposed pad to a dedicated PCB ground plane with multiple thermal vias for junction temperature control (θJC = 3°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar upconverting mixer applications.

Compared with ADL5801ACPZ-R7 and MAX2039ETX+, the LT5579IUH#TRPBF delivers superior OIP3 and lower noise floor in the 2–3.5GHz band, making it the preferred choice for high-performance macro base station transmitters where spectral purity and dynamic range are critical.

Availability

LT5579IUH#TRPBF is available at Aetrix Electronics and suitable for W-CDMA base stations, LTE macro cells, and WiMAX infrastructure requiring stable component supply across extended product lifecycles.

Supply support for LT5579IUH#TRPBF 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

Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and RF ICs, formed through the acquisition of Linear Technology in 2017.

The LT5579IUH#TRPBF belongs to ADI's high-linearity RF mixer product line, designed specifically for demanding wireless infrastructure transmitters where OIP3, noise floor, and LO efficiency directly impact base station coverage and spectral compliance.

FAQ

What is the recommended LO drive level for optimal performance of the LT5579IUH#TRPBF?

The LT5579IUH#TRPBF achieves best-in-class OIP3 and noise figure at –1dBm LO input power. Performance degrades if LO drive falls below –5dBm or exceeds +2dBm. The datasheet specifies –1dBm as the typical condition for all AC specifications including +27.3dBm OIP3 at 2140MHz. Maintaining this level ensures minimal conversion gain variation and LO leakage.

Can the LT5579IUH#TRPBF operate outside its specified 1.5GHz–3.8GHz RF range?

Yes - the LT5579IUH#TRPBF can operate down to 900MHz and up to 3900MHz, though with reduced performance. At 1750MHz, conversion gain drops to 1.8dB and OIP3 to 29dBm; at 3600MHz, gain becomes –0.5dB and OIP3 falls to 23.2dBm. Operation below 1500MHz requires careful RF output matching due to transformer inductance limitations.

How should the exposed pad (Pin 25) of the LT5579IUH#TRPBF be handled on the PCB?

The exposed pad (Pin 25) of the LT5579IUH#TRPBF must be soldered to a low-impedance RF ground plane on the PCB. It serves as both the primary thermal dissipation path (θJC = 3°C/W) and the main ground reference. At least six 0.3mm vias connecting the pad to inner ground layers are recommended to maintain junction temperature below 150°C at full 226mA supply current.

What is the function of the IF+ and IF– pins on the LT5579IUH#TRPBF?

The IF+ and IF– pins on the LT5579IUH#TRPBF form a differential intermediate frequency input port biased internally to 570mV common-mode voltage. They connect directly to the emitter nodes of the double-balanced mixer core. External 11Ω resistors and 40nH inductors set ~50mA bias current per side, while C1/C2 capacitors cancel transformer parasitics to optimize LO-to-RF isolation and return loss.

Does the LT5579IUH#TRPBF require external matching components for RF output?

Yes - the LT5579IUH#TRPBF requires external matching on the RF output (Pin 15) for optimal performance. At 2140MHz, the recommended network is a 0.45pF capacitor in series with a 3.9nH inductor to transform the internal 116–j21Ω impedance to 50Ω. Matching is frequency-specific: 3600MHz uses 0.7pF + 0Ω jumper, while 1750MHz uses 1.2pF + 6.8nH. Mismatch causes gain roll-off and degraded OIP3.