Analog Devices Inc. LT5554IUH#TRPBF

Overview

LT5554IUH#TRPBF from Analog Devices (formerly Linear Technology) is a 7-bit digitally controlled variable gain amplifier (VGA) with 16 dB gain control range, 0.125 dB step resolution, 1 GHz bandwidth, and –80 dB reverse isolation at 300 MHz. It integrates a 50 Ω input attenuator and high-linearity transconductance amplifier for IF sampling receivers and differential ADC driver applications.

For engineers reviewing the LT5554IUH#TRPBF datasheet, LT5554IUH#TRPBF pinout, LT5554IUH#TRPBF application, or LT5554IUH#TRPBF equivalent, key selection criteria include OIP3 ≥46 dBm at 200 MHz, 5 ns gain settling time, 1.4 nV/√Hz input-referred noise, differential 32-pin QFN package, and support for TTL/ECL-compatible digital control with strobe synchronization.

Technical Context

The LT5554IUH#TRPBF implements a two-stage architecture: a coarse 4 dB-step input attenuator (controlled by PG5/PG6) followed by a fine 0.125 dB-step transconductance amplifier (controlled by PG0–PG4). Gain updates are synchronized via STROBE to eliminate timing skew across the seven parallel control lines.

Its open-collector outputs feature an internal 400 Ω output resistance (RO), enabling unconditional stability into reactive loads including SAW filters. Internal biasing, on-chip voltage regulation, and overdrive protection ensure robust operation across –40°C to +85°C ambient temperature.

Key Specifications

Pinout & Package

LT5554IUH#TRPBF is housed in a 32-lead (5 mm × 5 mm) plastic QFN package with exposed thermal pad (Pin 33, GND). The package supports high-density RF layout and efficient heat dissipation when the exposed pad is soldered to PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADL5330ACPZ-R7 and HMC624LP4E, the LT5554IUH#TRPBF offers superior noise performance (1.4 nV/√Hz), finer gain resolution (0.125 dB), and integrated digital control-making it optimal for precision IF sampling and metrology-grade instrumentation where amplitude fidelity and repeatability are critical.

Availability

LT5554IUH#TRPBF is available at Aetrix Electronics and suitable for IF sampling receivers, differential ADC drivers, and instrumentation signal conditioning requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LT5554IUH#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 digital signal processing technologies, serving communications, industrial, automotive, and healthcare markets.

The LT5554IUH#TRPBF belongs to ADI's high-linearity RF VGA product line, designed specifically for demanding IF signal chain applications requiring ultra-low distortion, fast gain agility, and precise amplitude control in test & measurement and wireless infrastructure systems.

FAQ

What is the maximum gain and gain control range of the LT5554IUH#TRPBF?

The LT5554IUH#TRPBF provides a maximum voltage gain of 19.7 dB and a total gain control range of 16 dB (from 2 dB to 18 dB at ROUT = 50 Ω). Its 7-bit architecture delivers 128 discrete gain states with 0.125 dB fine steps and 4 dB coarse steps, enabling highly granular amplitude adjustment across its 1 GHz bandwidth. This makes the LT5554IUH#TRPBF ideal for closed-loop AGC systems requiring sub-dB resolution.

How does the STROBE input function in the LT5554IUH#TRPBF?

The STROBE input on the LT5554IUH#TRPBF synchronizes updates to the 7-bit gain control word (PG0–PG6). A positive transition on STROBE latches the current PGx states, eliminating timing skew between bits and preventing transient gain glitches. In transparent mode (STROBE high), gain changes occur asynchronously; in latch mode (STROBE low), gain remains stable regardless of PGx transitions. This ensures deterministic, jitter-free gain switching critical for time-sensitive IF processing in the LT5554IUH#TRPBF.

What is the recommended output interface configuration for the LT5554IUH#TRPBF?

The LT5554IUH#TRPBF features open-collector differential outputs (OUT+, OUT–) with an internal 400 Ω output resistance (RO). It requires external DC bias return via a center-tapped transformer or choke inductor tied to VCCO (5–6 V). This configuration maintains optimal linearity and reverse isolation while allowing flexible termination into 50 Ω or 100 Ω loads. Incorrect termination-such as direct 50 Ω resistive loading without DC return-degrades OIP3 and causes gain compression in the LT5554IUH#TRPBF.

Does the LT5554IUH#TRPBF support both AC- and DC-coupled digital control inputs?

Yes, the LT5554IUH#TRPBF supports both AC- and DC-coupled operation for its PGx and STROBE inputs, selected via the MODE pin. When MODE ≥ VCC – 0.4 V, inputs accept standard TTL/ECL logic levels (VIH = 2.2 V, VIL = 0.6 V). When MODE ≤ 0.6 V, inputs operate in AC-coupled mode, accepting 0.6 VP-P minimum pulses with fast edges (<5 ns rise/fall). This dual-mode flexibility allows seamless integration with FPGA, ASIC, or legacy logic families without level-shifting components in the LT5554IUH#TRPBF design.

What thermal management considerations apply to the LT5554IUH#TRPBF?

The LT5554IUH#TRPBF uses a 32-lead QFN package with an exposed thermal pad (Pin 33) that must be soldered to the PCB ground plane. With θJA = 34°C/W and θJC = 3°C/W, proper thermal vias and copper area under the pad are essential to maintain junction temperature ≤125°C at full load (106 mA ICC). Operating above +85°C ambient or neglecting pad soldering risks gain drift, increased noise, and accelerated parametric shift-particularly in high-reliability instrumentation using the LT5554IUH#TRPBF.