Analog Devices Inc. HMC629LP4

Overview

HMC629LP4 from Analog Devices (formerly Hittite Microwave) is a GaAs MMIC 4-bit digital RF attenuator with 3 dB LSB steps, DC–6 GHz bandwidth, 2.5 dB typical insertion loss, and 45 dB maximum attenuation range. It operates from a single +3 V or +5 V supply and supports TTL/CMOS-compatible serial (SPI), parallel, and latched parallel control for cellular infrastructure, microwave radio, and test equipment signal conditioning.

For engineers reviewing the HMC629LP4 datasheet, HMC629LP4 pinout, HMC629LP4 application, or HMC629LP4 equivalent, this device delivers verified ±0.25 dB typical step error, RoHS-compliant 4×4 mm QFN packaging, dual-mode digital interface flexibility, and near-DC operation enabled by off-chip AC ground capacitors - critical for IF/RF gain control and calibration loops.

Technical Context

The HMC629LP4 integrates a monolithic GaAs MMIC core with on-die switching elements and bias circuitry optimized for broadband RF attenuation. Its architecture supports three distinct control modes-serial (3-wire SPI), direct parallel, and latched parallel-each governed by the P/S pin state and LE timing.

It features internal power-up state selection via PUP1/PUP2 pins, 24-lead QFN package with exposed paddle for thermal management, and requires external ACG capacitors (pins 6–13) to extend low-frequency response down to DC. Return loss exceeds 17 dB across all attenuation states at DC–6 GHz.

Key Specifications

Pinout & Package

The HMC629LP4 is housed in a RoHS-compliant 4×4 mm, 24-lead QFN package with exposed thermal paddle. All ground leads (pins 4, 15, and paddle) must be soldered to PCB RF ground per AN-xxx QFN layout guidelines.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digital RF attenuator applications.

Compared with HMC1082LP4E and ADL5240, the HMC629LP4 uniquely balances DC–6 GHz coverage, 2.5 dB low insertion loss, and flexible digital interface - making it the preferred choice for broadband RF infrastructure where both low-frequency reach and digital programmability are required.

Availability

HMC629LP4 is available at Aetrix Electronics and suitable for cellular infrastructure, microwave radio, and RF test equipment requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for HMC629LP4 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 Hittite Microwave in 2014 and now owns the HMC product line. The company specializes in high-performance analog, RF, and mixed-signal semiconductors for communications, instrumentation, and defense.

The HMC629LP4 belongs to Analog Devices' broadband RF attenuator family, designed specifically for digitally programmable gain control in wireless infrastructure, aerospace, and automated test systems demanding DC–6 GHz performance and robust digital interface options.

FAQ

What is the operating frequency range of the HMC629LP4?

The HMC629LP4 operates from DC to 6 GHz. This broadband range supports both IF and RF applications, including cellular infrastructure, microwave radios, and test equipment. Its DC coupling capability-enabled by external AC ground capacitors on pins 6–13-allows use down to near-DC frequencies, unlike many competing attenuators limited to 100 MHz minimum.

Does the HMC629LP4 support both serial and parallel digital control?

Yes, the HMC629LP4 supports three control modes: 3-wire SPI serial (SERIN/CLK/LE), direct parallel (D3–D0 with LE high), and latched parallel (D3–D0 loaded on LE pulse). Mode selection is controlled by the P/S pin. All modes are TTL/CMOS compatible and operate from a single +3 V or +5 V supply, enabling flexible integration with FPGAs, microcontrollers, or ASICs.

What is the attenuation accuracy specification for the HMC629LP4?

The HMC629LP4 has an attenuation accuracy of ±(0.50 + 5% of attenuation setting) maximum, referenced to insertion loss. For example, at a 20 dB setting, accuracy is ±1.5 dB max. Typical step error is ±0.25 dB, ensuring consistent amplitude resolution across all 16 states - critical for calibration-critical applications like RF power meter front-ends and vector signal analyzers.

How is the power-up state configured on the HMC629LP4?

The HMC629LP4 uses PUP1 and PUP2 pins to define its power-up attenuation state. When LE is low at power-up, the PUP truth table selects either 45 dB or insertion loss (0 dB) based on PUP1/PUP2 logic levels. If LE is high at power-up, the D3–D0 parallel inputs determine the initial state. The part latches the selected state ~200 ms after power-on, ensuring deterministic behavior in automated systems.

What package type and thermal characteristics does the HMC629LP4 have?

The HMC629LP4 uses a 4×4 mm, 24-lead QFN package with exposed thermal paddle and Sn/Pb lead finish (MSL1). Its thermal resistance is 98.5°C/W, and continuous power dissipation is 0.66 W at +85°C (derated above that temperature). Proper grounding of pins 4, 15, and the paddle to a multilayer PCB ground plane is mandatory to maintain RF performance and thermal reliability.