Analog Devices Inc. 126830-HMC905LP3E

Overview

HMC905LP3E from Analog Devices (formerly Hittite Microwave) is a SiGe BiCMOS programmable RF frequency divider IC used for low-noise clock and LO generation in high-frequency signal chains. It supports division ratios N = 1 to 4 across a 400 MHz–6 GHz input range, delivers up to +6 dBm single-ended output power with -164 dBc/Hz SSB phase noise at 10 MHz offset (N=4), and features configurable bias/output control and <1 µA sleep current.

For engineers reviewing the HMC905LP3E datasheet, HMC905LP3E pinout, HMC905LP3E application, or HMC905LP3E equivalent, this device is selected for fast-switching synthesizers, software-defined radios, and military/test equipment where low phase noise, wideband operation, and programmable division are critical design requirements.

Technical Context

The HMC905LP3E implements a fully differential SiGe BiCMOS divider core with digital programming of division ratio via two logic inputs (B1/B0), enabling precise N = 1, 2, 3, or 4 selection. Its open-drain differential outputs (IOUTP/IOUTN) require external 50 Ω pull-up to Vcc for proper termination and 50% duty cycle generation.

It integrates independent digital controls for chip enable (EN), output buffer power (CTRL), and core bias (BIAS1/BIAS0), allowing dynamic optimization of current consumption (82–125 mA), output power (-2 to +6 dBm), and phase noise performance. Input-to-output isolation exceeds -30 dBc when EN is disabled.

Key Specifications

Pinout & Package

16-lead 3×3 mm leadless surface-mount package (MSL1, RoHS-compliant, matte Sn finish); ground paddle must be soldered to PCB RF ground per Hittite application note.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar programmable RF divider applications.

Compared with HMC905LP3E, HMC988LP4E trades programmability for bandwidth and LTC6957-4 replaces parallel logic control with SPI while improving phase noise - both require layout and firmware changes, and none are pin-compatible replacements.

Availability

HMC905LP3E is available at Aetrix Electronics and suitable for LO generation, software-defined radio development, and fast-switching synthesizer designs requiring stable component supply across industrial, defense, and test equipment programs.

Supply support for HMC905LP3E 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 maintains its high-frequency RF product portfolio, emphasizing performance, reliability, and application-specific integration for demanding wireless infrastructure and defense systems.

The HMC905LP3E belongs to Hittite's legacy RF frequency divider family, designed specifically for low-noise, wideband, and fast-reconfiguration LO and clock generation in microwave and millimeter-wave signal chains.

FAQ

What is the maximum input frequency supported by the HMC905LP3E at each division ratio?

The HMC905LP3E supports up to 6 GHz input frequency for all division ratios N = 1–4, though the datasheet notes a reduced maximum of 5500 MHz specifically for N = 2. This limitation reflects internal bandwidth constraints under that configuration, not a general operating restriction. The device remains fully functional across its full 400 MHz–6 GHz range for N = 1, 3, and 4, making the HMC905LP3E versatile for multi-ratio frequency planning in broadband synthesizers.

How does the HMC905LP3E achieve its -164 dBc/Hz phase noise performance?

The HMC905LP3E achieves -164 dBc/Hz SSB phase noise at 10 MHz offset (N = 4) through its SiGe BiCMOS process, optimized differential divider core, and low-noise bias architecture. Performance is measured under specified conditions: +6 dBm input power at 6 GHz, single-ended input/output, and proper 50 Ω termination. The HMC905LP3E's phase noise scales with input power and division ratio - lower input levels or higher N values degrade noise floor, so design must follow recommended operating windows in the datasheet.

Can the HMC905LP3E operate with single-ended RF input and output?

Yes, the HMC905LP3E supports single-ended operation: apply the RF signal to RFINP (Pin 2) and terminate RFINN (Pin 3) with 50 Ω to ground. For output, use either IOUTP (Pin 11) or IOUTN (Pin 10) with the other terminated in 50 Ω, and connect a 50 Ω pull-up resistor from the active output to Vcc. This configuration yields ~3 dB less output power than differential mode but retains full functionality, including programmable division and low phase noise, as verified on the evaluation board (126830).

What is the purpose of the BIAS0 and BIAS1 pins on the HMC905LP3E?

The BIAS0 and BIAS1 pins on the HMC905LP3E configure the core bias current to optimize trade-offs among output power, phase noise, and supply current. Four combinations (00, 01, 10, 11) set distinct operating points - e.g., BIAS1/BIAS0 = 01 yields 120 mA typical current and +6.3 dBm output, while 00 gives 84 mA and +1.5 dBm. The datasheet explicitly warns against BIAS1/BIAS0 = 11, which is not recommended. These pins allow designers to tune the HMC905LP3E for specific system-level power and noise targets without hardware changes.

Does the HMC905LP3E require an external low-dropout regulator (LDO)?

Yes, the HMC905LP3E datasheet specifies that its analog supply (Vcc) should be delivered via a low-noise LDO - explicitly recommending the HMC860LP3E - to preserve its ultra-low phase noise performance. While the device operates across 3.15–3.45 V, supply ripple or noise directly modulates the divider core and degrades SSB phase noise. Using a dedicated, filtered LDO rather than a switching regulator or shared rail prevents spurious sidebands and ensures the HMC905LP3E meets its -164 dBc/Hz specification in production systems.