Analog Devices Inc. LT5572EUF#PBF

Overview

LT5572EUF#PBF from Analog Devices (acquired Linear Technology) is a high-linearity direct quadrature modulator IC for wireless infrastructure transmitters, operating from 1.5GHz to 2.5GHz RF with –2.5dB conversion gain, +21.6dBm OIP3 at 2GHz, –41.2dBc image rejection, and integrated LO quadrature generator. It enables DC-coupled I/Q baseband-to-RF upconversion in DCS, PCS, and UMTS band basestations.

For engineers reviewing the LT5572EUF#PBF datasheet, LT5572EUF#PBF pinout, LT5572EUF#PBF application, or LT5572EUF#PBF equivalent, key selection criteria include RF frequency range (1.5–2.5GHz), baseband common-mode voltage (0.5V), 16-lead 4mm × 4mm QFN package, and performance trade-offs between carrier leakage (–39.4dBm), noise floor (–152.5dBm/Hz at POUT = 4dBm), and supply current (145mA typical).

Technical Context

The LT5572EUF#PBF implements a fully integrated direct-conversion transmitter architecture: differential baseband I/Q inputs drive voltage-to-current converters feeding double-balanced mixers; an on-chip RF balun sums mixer outputs and transforms to 50Ω single-ended RF output. The LO path includes a single-ended buffer and precision quadrature phase generator delivering accurate 0°/90° LO signals to both mixers.

Its high-impedance (90kΩ) DC-coupled baseband interface requires 0.5V common-mode bias and supports up to 460MHz baseband bandwidth; RF and LO ports are AC-coupled, 50Ω matched, and operate across –40°C to 85°C ambient temperature with 4.5V–5.25V supply.

Key Specifications

Pinout & Package

LT5572EUF#PBF is housed in a 16-lead plastic QFN package (4mm × 4mm) with exposed thermal pad (Pin 17) that must be soldered to PCB ground for RF performance and thermal management.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar direct quadrature modulator applications.

Compared with ADL5375-05 and TRF3705, the LT5572EUF#PBF delivers superior integration (on-chip quadrature LO generation), tighter I/Q matching (0.07dB/0.9°), and optimized power efficiency (145mA) for fixed-band 1.5–2.5GHz infrastructure transmitters - reducing bill-of-materials and layout risk.

Availability

LT5572EUF#PBF is available at Aetrix Electronics and suitable for wireless infrastructure basestations, macrocell transmitters, and 3G/4G small cell radio units requiring stable component supply, long-term lifecycle support, and traceable sourcing for telecom OEMs.

Supply support for LT5572EUF#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and RF ICs, formed through acquisition of Linear Technology in 2017.

The LT5572EUF#PBF belongs to ADI's high-linearity RF modulator product line, designed specifically for wireless infrastructure transmitters demanding low distortion, integrated LO synthesis, and robust thermal performance in basestation environments.

FAQ

What is the recommended baseband common-mode voltage for optimal performance of the LT5572EUF#PBF?

The LT5572EUF#PBF achieves best linearity and image rejection at a 0.5V DC common-mode voltage applied to all four baseband inputs (BBPI, BBMI, BBPQ, BBMQ). Deviating from this value - for example to 0.6V - increases carrier leakage and degrades OIP3 by up to 3dB, as confirmed in Table 1 of the datasheet. Maintaining 0.5V ensures the internal PNP emitter followers operate within their linear region.

Does the LT5572EUF#PBF require external LO quadrature generation?

No, the LT5572EUF#PBF integrates a precision LO quadrature phase generator and buffers, eliminating the need for external 90° hybrids or polyphase filters. This internal circuitry delivers stable 0° and 90° LO signals to the I and Q mixers across 1.5–2.5GHz, achieving <1° phase error at 2GHz - a key factor enabling its –41.2dBc image rejection without calibration.

How does the LT5572EUF#PBF handle power-down sequencing?

The LT5572EUF#PBF uses a dedicated EN pin (Pin 1) for controlled shutdown: applying <0.5V disables the device, reducing supply current to 50µA in 1.3µs; applying >1V enables full operation with 145mA draw. An internal 75kΩ pull-down resistor guarantees safe default-OFF state if EN is left floating - preventing unintended RF output during power-up/down transitions.

What is the maximum RF output power achievable with the LT5572EUF#PBF at 2.14GHz?

The LT5572EUF#PBF delivers up to +6.2dBm CW RF output power at 2.14GHz when driven with full-scale 2VP-P differential baseband signals (0V–1V swing per side). This limit arises from internal baseband voltage headroom constraints at 0.5V common-mode bias - exceeding it risks clipping and increased HD2/HD3 distortion, as shown in Figure G19 of the datasheet.

Can the LT5572EUF#PBF be used in TDD systems requiring fast transmit/receive switching?

Yes, the LT5572EUF#PBF supports TDD operation via its EN pin, achieving 0.25µs turn-on time (EN low→high) and 1.3µs turn-off time (EN high→low), allowing rapid activation/deactivation between transmit and receive slots. Its 50µA sleep current minimizes power consumption during receive periods, making it suitable for TD-SCDMA and TDD-LTE basestation architectures.