Analog Devices Inc. LT5578IUH#PBF

Overview

LT5578IUH#PBF from Analog Devices (formerly Linear Technology) is a high-linearity, single-ended LO and RF upconverting mixer optimized for 0.4–2.7 GHz RF output in LTE, W-CDMA, and WiMAX basestations. It delivers 1.4 dB conversion gain at 900 MHz, 27 dBm OIP3 at 0.9 GHz, –158 dBm/Hz noise floor at –5 dBm POUT, –43 dBm LO-to-RF leakage, and operates from a single 3.3 V supply.

For engineers reviewing the LT5578IUH#PBF datasheet, LT5578IUH#PBF pinout, LT5578IUH#PBF application, or LT5578IUH#PBF equivalent, key selection criteria include its high OIP3 vs. frequency trade-off, low LO drive requirement (–1 dBm), differential IF input interface, thermal performance via exposed pad grounding, and QFN24 package compatibility with LT5579.

Technical Context

The LT5578IUH#PBF integrates a high-performance LO buffer amplifier driving a double-balanced mixer core with internal baluns to enable single-ended LO input and RF output while maintaining differential IF interface. Its architecture minimizes LO signal contamination through balanced design and internal transformer coupling.

It supports high-side and low-side LO injection across its full 400–3000 MHz LO range, with IF input bandwidth spanning DC to 600 MHz. Performance is characterized at three key bands: 740 MHz (gain = 0.8 dB, OIP3 = 26.5 dBm), 900 MHz (gain = 1.4 dB, OIP3 = 27.0 dBm), and 1950 MHz (gain = –0.7 dB, OIP3 = 24.3 dBm), all at 3.3 V and 25°C.

Key Specifications

Pinout & Package

LT5578IUH#PBF is housed in a 5 mm × 5 mm plastic QFN-24 package (UH) with an exposed thermal pad (Pin 25) that must be soldered to PCB ground for electrical integrity and thermal dissipation. The package is RoHS-compliant and lead-free (PBF suffix).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LT5579IUH#PBF, the LT5578IUH#PBF offers lower LO drive and identical footprint for cost-sensitive LTE infrastructure; versus ADL5801ACPZ-R7, it trades 3.5 dB OIP3 for 8 dB lower LO power and guaranteed pin compatibility with existing LT5579 layouts.

Availability

LT5578IUH#PBF is available at Aetrix Electronics and suitable for LTE basestation transmitters, W-CDMA infrastructure nodes, and public safety radio systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LT5578IUH#PBF 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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for legacy Linear RF components.

The LT5578IUH#PBF belongs to Linear's high-performance RF mixer family designed specifically for wireless infrastructure transmitters demanding high linearity, low noise, and simplified LO interface in compact form factors.

FAQ

What is the minimum LO drive level required for specified performance of the LT5578IUH#PBF?

The LT5578IUH#PBF is fully characterized at –1 dBm LO input power, delivering 1.4 dB conversion gain and 27 dBm OIP3 at 900 MHz. Operation down to –5 dBm is supported per AC specifications, though gain drops ~0.5 dB and OIP3 decreases ~1.5 dB at that level. The LT5578IUH#PBF does not require external LO amplification in most 3G/4G basestation designs.

Can the LT5578IUH#PBF be used for frequencies below 400 MHz RF output?

The LT5578IUH#PBF is specified for 400–2700 MHz RF output. While functional down to ~300 MHz, internal transformer inductance limits gain flatness and return loss; measured gain falls to –2.1 dB and NF rises to 9.3 dB at 450 MHz. For sub-400 MHz use, the LT5578IUH#PBF requires custom matching and exhibits degraded OIP3 and noise figure versus datasheet specs.

How should the exposed thermal pad (Pin 25) of the LT5578IUH#PBF be connected on the PCB?

The exposed pad of the LT5578IUH#PBF must be soldered directly to a low-impedance RF ground plane using ≥6 thermal vias (0.3 mm diameter, spaced ≤1 mm apart) connecting to inner ground layers. This achieves the rated θJA = 34°C/W and prevents gain compression and NF degradation above 60°C junction temperature. Solder mask must be removed from the pad area.

Does the LT5578IUH#PBF support both high-side and low-side LO injection?

Yes, the LT5578IUH#PBF supports both high-side and low-side LO injection across its full 400–3000 MHz LO range. At 900 MHz RF output, low-side LO (760 MHz) yields 1.4 dB gain and 27 dBm OIP3, while high-side LO (1040 MHz) gives –0.2 dB gain and 26.5 dBm OIP3. The LT5578IUH#PBF requires no hardware change between configurations-only LO synthesizer tuning.

What is the recommended IF input termination for optimal performance of the LT5578IUH#PBF?

The LT5578IUH#PBF IF inputs (Pins 3, 4) require external 13.7 Ω resistors to ground to set the optimal 40 mA per-side bias current. These resistors must be 0.1% tolerance, low-inductance types placed within 2 mm of the pins. Inductors (100 nH) in series with the resistors reduce loading effects, and 220 pF capacitors provide DC blocking and parasitic cancellation per the Figure 1 test circuit.