Analog Devices Inc. ADF4218BRU

Overview

ADF4218BRU from Analog Devices is a dual RF/IF PLL frequency synthesizer IC designed for local oscillator generation in wireless transceivers, supporting RF input up to 2.5 GHz and IF input up to 550 MHz with 2.7–5.5 V supply, selectable dual-modulus prescalers (32/33 or 64/65 for RF), and integrated phase-frequency detector with precision charge pump. It enables simultaneous LO synthesis for both RF and IF signal paths in GSM, WCDMA, and wireless LAN systems.

For engineers reviewing the ADF4218BRU datasheet, ADF4218BRU pinout, ADF4218BRU application, or ADF4218BRU equivalent, this page delivers verified specifications, TSSOP-20 package details, functional pin roles, real-world use cases in base station and handset RF front-ends, and two validated alternative synthesizers with documented technical and application differences.

Technical Context

The ADF4218BRU implements two independent PLL channels - one for RF (up to 2.5 GHz) and one for IF (up to 550 MHz) - each with its own 11-bit B-counter, 6-bit A-counter, dual-modulus prescaler (32/33 or 64/65 on RF side), and 14-bit R-counter. Its PFD operates at up to 40 MHz, and charge pump current is programmable at 1.125 mA or 4.5 mA typical.

It supports asynchronous or synchronous power-down per channel, analog lock detect via MUXOUT with external 10 kΩ pull-up, and 3-wire serial interface (CLK/DATA/LE) with 22-bit shift register and latch-select control bits. All registers are CMOS-compatible and operate across –40°C to +85°C.

Key Specifications

Pinout & Package

TSSOP-20 package (RU-20), 0.65 mm pitch, thermally enhanced with exposed pad (not electrically connected); requires analog/digital ground separation and local decoupling on VDD1/VDD2/VP1/VP2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual PLL frequency synthesizer applications.

Compared with ADF4218BRU, ADF4158BRUZ offers higher RF frequency and fractional-N capability but sacrifices IF synthesis and dual-channel independence; LMX2531LQ1580E integrates the VCO but removes all IF functionality and prescaler configurability, making it unsuitable for traditional superheterodyne base stations.

Availability

ADF4218BRU is available at Aetrix Electronics and suitable for wireless infrastructure, handheld communications, test instrumentation, and CATV equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for ADF4218BRU 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 is a global leader in high-performance analog, mixed-signal, and RF ICs, serving precision instrumentation, communications, and industrial markets since 1965.

The ADF421x family was engineered specifically for dual-conversion wireless transceivers, delivering independent RF and IF PLL synthesis with low phase noise, flexible prescaling, and robust lock detection in a single TSSOP-20 package.

FAQ

What is the maximum RF input frequency supported by the ADF4218BRU?

The ADF4218BRU supports an RF input frequency range of 0.5 GHz to 2.5 GHz at 5 V supply, as confirmed in the "RF/IF CHARACTERISTICS (5 V)" table on page 2 of the datasheet. This makes it suitable for WCDMA Band I (2100 MHz) and LTE Band 7 (2600 MHz) front-end LO generation when paired with appropriate external VCOs and loop filters.

Does the ADF4218BRU include an integrated VCO?

No, the ADF4218BRU does not include an integrated VCO. It is a PLL frequency synthesizer IC that drives external VCOs via its CPRF and CPIF charge pump outputs. The device requires external loop filters and voltage-controlled oscillators to complete the PLL system, as explicitly stated in the General Description section: "A complete PLL can be implemented if the synthesizers are used with an external loop filter and VCOs."

How is lock detection implemented on the ADF4218BRU?

Lock detection on the ADF4218BRU is implemented via the MUXOUT pin configured for analog lock detect mode. When enabled, MUXOUT becomes an open-drain N-channel output requiring a 10 kΩ external pull-up resistor. In lock, it presents a logic high with narrow low-going pulses - a behavior confirmed in the "MUXOUT AND LOCK DETECT" section (page 11) and functional block diagram.

Can the ADF4218BRU operate with a 3.3 V supply?

Yes, the ADF4218BRU operates over a 2.7 V to 5.5 V supply range, including standard 3.3 V systems. Electrical specifications such as RF input sensitivity (–15/+4 dBm), phase noise (–90 dBc/Hz @ 1 kHz), and current consumption (14 mA typical RF+IF at 3 V, 25°C) are all characterized at 3 V per the "SPECIFICATIONS" table on page 2.

What package type is used for the ADF4218BRU?

The ADF4218BRU is housed in a Thin Shrink Small Outline Package (TSSOP) with 20 leads (RU-20), as specified in the Ordering Guide on page 5 of the datasheet. This thermally enhanced surface-mount package features a 0.65 mm lead pitch and is RoHS-compliant.