Analog Devices Inc. HMC765LP6CETR

Overview

HMC765LP6CETR from Analog Devices (formerly Hittite Microwave) is a fully integrated Fractional-N PLL with on-die VCO, operating from 7.8 GHz to 8.8 GHz. It delivers 13 dBm RF output power, supports 24-bit fractional resolution (3 Hz typical step size), and achieves ultra-low in-band phase noise of –97 dBc/Hz @ 10 kHz offset (fractional mode, 50 MHz reference). It is used as a local oscillator synthesizer in microwave radio transceivers.

For engineers reviewing the HMC765LP6CETR datasheet, HMC765LP6CETR pinout, HMC765LP6CETR application, or HMC765LP6CETR equivalent, key selection criteria include its 7.8–8.8 GHz VCO range, integrated cycle slip prevention, direct FSK modulation capability, 40-lead 6 × 6 mm QFN package, and dual-supply architecture (3.3 V digital/analog + 5 V VCO/charge pump).

Technical Context

The HMC765LP6CETR implements a delta-sigma modulator-based fractional-N architecture with programmable integer/fractional modes, enabling fine frequency resolution and low spurious content. Its integrated VCO eliminates external tuning components while maintaining <±10 MHz/V pushing and <±0.9 MHz/°C drift over temperature.

It features a dual-domain power supply system: 3.3 V for logic, reference path, prescaler, and analog sections (AVCC, AVDD, RVDD, DVDD), and 5 V for VCO core and charge pump (VCCVCO1/2, VDDCP, VCCCP). The serial interface supports up to 50 MHz SCK with chip ID readback and lock detect output.

Key Specifications

Pinout & Package

Package: 40-lead, 6 × 6 mm leadless QFN (RoHS-compliant, MSL3, exposed ground paddle). Thermal resistance θ_JA = 38.4 °C/W (junction to ground paddle, 5 V supply).

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC765LP6CETR, HMC764LP6CE trades bandwidth and advanced modulation for lower cost in fixed-band systems, while ADF4371BCPZ expands frequency range and integration at the expense of higher power and reduced phase noise optimization in the 7.8–8.8 GHz band.

Availability

HMC765LP6CETR is available at Aetrix Electronics and suitable for VSAT terminals, point-to-point radios, and military communications systems requiring stable component supply, long-term obsolescence management, and guaranteed RF performance across –40°C to +85°C.

Supply support for HMC765LP6CETR 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 lines. Hittite specialized in microwave ICs for defense, aerospace, and communications infrastructure.

The HMC765LP6CETR belongs to Hittite's "PLLS w/ Integrated VCO" product line, designed specifically for microwave radio LO generation where ultra-low phase noise, fast settling, and single-chip integration are critical.

FAQ

What is the recommended power supply sequencing for HMC765LP6CETR?

HMC765LP6CETR requires strict power-up order: apply 3.3 V supplies (AVCC, AVDD, DVDD, etc.) first, then 5 V supplies (VCCVCO1/2, VDDCP). Reverse sequencing may cause latch-up or undefined state. The device draws 290 mA total at 5 V and 110 mA at 3.3 V under typical operation. Always use local ceramic decoupling (100 nF + 10 nF) per supply pin.

Does HMC765LP6CETR support both fractional and integer-N modes simultaneously?

No - HMC765LP6CETR operates in either fractional-N or integer-N mode per configuration, selected via register bit FRAC_EN. Fractional mode enables 3 Hz resolution and fine channel spacing; integer mode delivers lower in-band spurs and simpler loop filter design. Mode switching requires full register reconfiguration and lock reacquisition.

Can HMC765LP6CETR drive a passive mixer directly without an amplifier?

Yes - HMC765LP6CETR delivers 13 dBm typical RF output power into 50 Ω, matching the LO drive requirement of many Hittite/Analog Devices passive mixers (e.g., HMC774A, HMC1048). No external buffer is needed if the mixer's specified LO drive level is ≤13 dBm and impedance match is maintained via proper AC coupling and layout.

What is the function of Pin 20 (BIAS) on HMC765LP6CETR?

Pin 20 (BIAS) provides a precision 1.920 V ±20 mV internal reference voltage for biasing sensitive analog circuits. It must be measured with a 10 GΩ meter (e.g., Agilent 34410A); standard 10 MΩ DVMs will load the node and read incorrectly. Do not connect external loads - it is not intended to source current.

Is HMC765LP6CETR pin-compatible with other Hittite PLL+VCO devices?

HMC765LP6CETR shares the same 40-lead 6 × 6 mm QFN footprint and pinout with the HMC764LP6CE and HMC766LP6CE families, enabling drop-in replacement within the 6–9 GHz range. Pins marked "NC" (e.g., Pin 1, 9–13) and unconnected VCCVCO2 (Pin 8) are retained for mechanical and thermal compatibility across the series.