Analog Devices Inc. LTC5555IUFD#PBF

Overview

LTC5555IUFD#PBF from Analog Devices is a 1.5GHz–7GHz programmable-gain downconverting mixer with integrated IF VGA, 9dB power conversion gain at 3.6GHz, 31dBm output IP3, and 0.5dB-step SPI/parallel gain control. It serves as the core RF-to-IF signal path in high-linearity wireless infrastructure receivers.

For engineers reviewing the LTC5555IUFD#PBF datasheet, LTC5555IUFD#PBF pinout, LTC5555IUFD#PBF application, or LTC5555IUFD#PBF equivalent, key selection criteria include its 28-pin 4mm×5mm QFN package, dual-supply operation (3.3V VCC / 1.8–3.3V VDD), differential IF output impedance (206Ω || 1pF), and guaranteed –40°C to 105°C case temperature range.

Technical Context

The LTC5555IUFD#PBF integrates an active double-balanced mixer stage followed by a digitally controlled variable-gain amplifier (DVGA) with 15.5dB total attenuation range. Its RF input uses an integrated transformer for 50Ω single-ended matching, while LO accepts either single-ended or differential drive across 0.5–8GHz.

The IF path delivers differential outputs (IF+, IF–) with open-collector topology requiring external pull-up inductors, and supports 1–900MHz IF bandwidth. Gain programming occurs via 5-bit parallel interface (D0–D4) or 3-wire SPI (CSB/CLK/SDI/SDO), with EN enabling fast turn-on (<0.3µs) and RP selecting full/reduced power modes.

Key Specifications

Pinout & Package

Package: 28-lead (4mm × 5mm) plastic QFN with exposed thermal pad (Pin 29 = GND). Requires soldering of exposed pad to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC1040LP4CE and ADL5802ACPZ-R7, the LTC5555IUFD#PBF uniquely combines 1.5–7GHz RF coverage, 15.5dB programmable IF gain in 0.5dB steps, and dual SPI/parallel control-enabling adaptive receiver architectures without external gain stages or LO buffers.

Availability

LTC5555IUFD#PBF is available at Aetrix Electronics and suitable for 3.6GHz/4.8GHz/5.8GHz wireless infrastructure receivers, military radar receivers, software-defined radios, and test & measurement equipment requiring stable component supply across extended temperature ranges.

Supply support for LTC5555IUFD#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 is a global leader in high-performance analog, mixed-signal, and RF ICs, serving communications, industrial, automotive, and aerospace markets with precision signal processing solutions.

The LTC5555IUFD#PBF belongs to Analog Devices' high-frequency mixer product line, engineered for demanding wireless infrastructure and defense applications requiring wide bandwidth, high linearity, and programmable gain control in compact packages.

FAQ

What is the RF input impedance and matching requirement for LTC5555IUFD#PBF?

The LTC5555IUFD#PBF features an integrated RF transformer for single-ended 50Ω input matching, but external passive components are required per frequency band. Four defined matching bands (1.5–2.1GHz, 2.2–3.2GHz, 2.6–6.4GHz, 5.6–7.2GHz) each specify unique capacitor values (e.g., 6.8pF/1.8pF for 1.5–2.1GHz) to achieve >10dB return loss. The RF pin is internally biased to VCC/2, mandating a series DC-blocking capacitor.

How does the LTC5555IUFD#PBF handle LO drive requirements?

The LTC5555IUFD#PBF accepts either single-ended or differential LO drive across 0.5–8GHz, with LO+ and LO– pins internally matched to 50Ω and protected by ESD diodes. LO input power range is –6dBm to +6dBm, and LO return loss exceeds 9dB from 500MHz to 7GHz. DC-blocking capacitors are required only if the LO source presents DC voltage, as the pins are AC-coupled internally.

What are the power supply requirements and current consumption of LTC5555IUFD#PBF?

The LTC5555IUFD#PBF requires two supplies: 3.3V (VCC, ±0.3V) for the analog mixer core (225mA typical in full-power mode) and 1.8–3.3V (VDD) for digital interfaces (1mA typical active, <500µA idle). Shutdown current is 0.52mA. Both supplies must be locally bypassed; VCC defines logic thresholds for EN/PS, while VDD sets levels for SPI/parallel pins.

Can LTC5555IUFD#PBF operate outside its specified 1.5–7GHz RF range?

The LTC5555IUFD#PBF is characterized and optimized for 1.5–7GHz RF operation, with guaranteed performance (gain, NF, IIP3) within this band. While functional below 1.5GHz or above 7GHz, datasheet notes degradation in conversion gain, noise figure, and isolation outside the specified range. For reliable operation, use only within 1.5–7GHz with appropriate band-specific matching networks.

What is the function of the MO+ and MO– pins on LTC5555IUFD#PBF?

The MO+ and MO– pins on LTC5555IUFD#PBF are differential open-collector mixer outputs feeding the internal IF DVGA stage. They require external pull-up inductors (or transformer windings) to VCC and carry ~27mA DC bias per pin. These pins provide intermediate IF signal access before final gain adjustment, enabling flexible signal routing or external filtering between mixer and DVGA stages.