Analog Devices Inc. HMC837LP6CETR

Overview

HMC837LP6CETR from Analog Devices (formerly Hittite Microwave) is a fractional-N phase-locked loop frequency synthesizer with integrated tri-band VCO, delivering RF outputs at 1025–1150 MHz (fVCO/2), 2050–2300 MHz (fVCO), and 4100–4600 MHz (2fVCO), with ultra-low phase noise (−112 dBc/Hz typ. in-band), <180 fs RMS jitter, and 24-bit frequency resolution (3 Hz typ.). It serves as a high-performance clock source in cellular infrastructure transceivers requiring fast frequency hopping and spectral purity.

For engineers reviewing the HMC837LP6CETR datasheet, HMC837LP6CETR pinout, HMC837LP6CETR application, or HMC837LP6CETR equivalent, this device supports exact-frequency mode, built-in digital self-test, cycle-slip prevention for rapid settling, and operates across −40°C to +85°C in a 40-lead 6×6 mm QFN package with exposed paddle.

Technical Context

The HMC837LP6CETR integrates a low-noise delta-sigma fractional-N PLL, autocalibrating tri-band VCO, precision charge pump (0.02–2.54 mA), and low-noise reference path divider. Its phase detector incorporates cycle-slip prevention (CSP) to reduce frequency-hopping time while maintaining stability.

It supports three operating modes-integer, fractional feedback, and fractional feedforward-with configurable PFD frequencies up to 125 MHz (integer), 100 MHz (fractional feedback), and 80 MHz (fractional feedforward). Closed-loop phase noise reaches −115 dBc/Hz at 1 kHz offset (100 MHz PFD, 176 kHz loop BW), and integrated phase noise is −62 dBc (10 kHz–100 MHz).

Key Specifications

Pinout & Package

40-lead, 6×6 mm QFN package with exposed ground paddle (MSL1, RoHS-compliant, matte Sn finish, marking "H837"). Thermal resistance θ_J-PD = 20 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar fractional-N PLL with integrated VCO applications.

Compared with ADF4355BCPZ and LMS8001-SYNTH, the HMC837LP6CETR delivers superior phase noise floor and jitter performance within its defined tri-band ranges, includes on-chip VCO autocalibration for long-term stability, and supports exact-frequency mode - making it uniquely suitable for carrier-class wireless infrastructure where spectral purity and repeatability are non-negotiable.

Availability

HMC837LP6CETR is available at Aetrix Electronics and suitable for cellular infrastructure, phased array radar, and high-speed test equipment requiring stable component supply, full traceability, and long-term lifecycle support.

Supply support for HMC837LP6CETR 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 line, specializing in microwave/mmWave ICs for communications, defense, and instrumentation.

The HMC837LP6CETR belongs to the Hittite PLLs-with-Integrated-VCO family, designed specifically for carrier-grade wireless infrastructure demanding ultra-low phase noise, fast frequency agility, and multi-band operational flexibility without external VCO switching.

FAQ

What is the maximum phase detector frequency supported by the HMC837LP6CETR in integer mode?

The HMC837LP6CETR supports up to 125 MHz phase detector frequency in integer mode, provided the minimum N-divider value is respected. This enables fast loop bandwidths for rapid frequency settling in TDD systems. The actual achievable PFD rate depends on the selected VCO band and N value - for example, at 2100 MHz output, the maximum PFD is limited to fvco/20 = 105 MHz. HMC837LP6CETR's integer-mode specification ensures compatibility with high-speed reference clocks while maintaining loop stability.

Does the HMC837LP6CETR require external loop filter components?

Yes, the HMC837LP6CETR requires an external passive loop filter connected to the CP pin (Pin 4) to stabilize the PLL and shape its dynamic response. Four validated loop filter configurations are documented - including 78 kHz, 93 kHz, 142 kHz, and 176 kHz bandwidths - each with specific resistor and capacitor values. These filters directly determine key performance metrics such as lock time, phase margin, and integrated jitter. HMC837LP6CETR does not integrate active filtering or on-die compensation.

How does the tri-band VCO autocalibration work in the HMC837LP6CETR?

The HMC837LP6CETR performs automatic VCO band selection and tuning voltage calibration at power-up or upon command. It measures VCO frequency across capacitor bank settings (32 states), identifies the optimal band for target frequency, and sets VTUNE to center the VCO in that band. This process compensates for process, voltage, and temperature variations, ensuring repeatable startup and stable operation. HMC837LP6CETR's autocalibration occurs internally without host intervention and completes within microseconds.

Can the HMC837LP6CETR generate output at both fVCO/2 and 2fVCO simultaneously?

No, the HMC837LP6CETR cannot generate fVCO/2 and 2fVCO simultaneously from a single device. Its RF output is configured via register settings to operate in one of three modes: divide-by-2 (1025–1150 MHz), fundamental (2050–2300 MHz), or doubler (4100–4600 MHz). Mode selection is static per power-on or register write; concurrent dual-band output requires two separate HMC837LP6CETR units or external signal routing. The HMC837LP6CETR pinout and internal architecture support only one active RF path at a time.

What is the purpose of the BIAS pin (Pin 40) on the HMC837LP6CETR?

Pin 40 (BIAS) provides external access to an internally generated 1.920 V ±20 mV precision reference voltage used for biasing critical analog circuits. It is not intended to drive external loads - attempting to do so will degrade regulation accuracy. Measurement requires a high-impedance meter (≥10 GΩ), as standard 10 MΩ DVMs load the node and yield erroneous readings. HMC837LP6CETR relies on this stable bias for consistent charge pump gain and VCO tuning linearity across temperature.