Analog Devices Inc./Maxim Integrated MAX2751EUA+T

Overview

MAX2751EUA+T from Maxim Integrated is a monolithic voltage-controlled oscillator (VCO) designed for 2.12–2.26 GHz ISM-band RF systems, featuring factory-guaranteed tuning range, on-chip LC tank, and internally matched 50Ω output buffer delivering –3 dBm output power with <4 MHzp-p load pulling. It operates from +2.7V to +5.5V and supports Bluetooth and proprietary 2.4GHz radio transceivers.

For engineers reviewing the MAX2751EUA+T datasheet, MAX2751EUA+T pinout, MAX2751EUA+T application, or MAX2751EUA+T equivalent, key selection criteria include guaranteed 2120–2260 MHz tuning range, low 9.7–15.9 mA supply current across temperature, sub-1 µA shutdown current, 175–110 MHz/V tuning gain, and µMAX-8 package compatibility with high-frequency layout constraints.

Technical Context

The MAX2751EUA+T implements a fully differential LC oscillator core with integrated varactor and inductor elements, eliminating external tank components. Its dual-supply architecture separates VCC1 (oscillator bias) and VCC2 (buffer supply) to minimize supply pushing (1.3 MHz/V) and load pulling (4 MHzp-p).

Frequency control is achieved via high-impedance TUNE input (0.4–2.4 V), with <0.02 nA input current ensuring minimal loop filter loading. The buffered output includes an on-chip DC blocking capacitor and delivers stable –3 dBm into 50Ω without external matching.

Key Specifications

Pinout & Package

MAX2751EUA+T is housed in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), RoHS-compliant and tape-and-reel ready. Thermal reliefs on GND pads are not recommended due to RF grounding requirements.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar VCO applications.

Compared with MAX2752EUA+T and MAX2750EUA+T, the MAX2751EUA+T uniquely satisfies 2120–2260 MHz FHSS requirements with factory-guaranteed limits, making it the sole fit for Bluetooth and HomeRF systems needing 240–280 MHz IF translation.

Availability

MAX2751EUA+T is available at Aetrix Electronics and suitable for 2.4GHz Bluetooth ISM radio, HomeRF networking, and proprietary 2.4GHz wireless sensor applications requiring stable component supply, consistent parametric performance, and RoHS-compliant packaging.

Supply support for MAX2751EUA+T 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

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and RF ICs for communications, computing, consumer, and industrial markets.

The MAX2750/MAX2751/MAX2752 family delivers monolithic VCOs targeting compact, low-component-count 2.4GHz ISM-band transceivers with guaranteed frequency limits and integrated matching.

FAQ

What is the guaranteed frequency tuning range of the MAX2751EUA+T?

The MAX2751EUA+T has a factory-adjusted and production-tested guaranteed frequency tuning range of 2120 MHz to 2260 MHz across the full operating temperature range of –40°C to +85°C. This range is specified under standard test conditions (VTUNE = +0.4V to +2.4V, VCC = +2.7V to +5.5V, 50Ω load), and no system-level calibration is required to meet these limits. The MAX2751EUA+T achieves this with on-chip varactor and inductor integration.

Does the MAX2751EUA+T require external matching components at the RF output?

No, the MAX2751EUA+T does not require external matching components at the RF output. Its OUT pin (Pin 7) incorporates an internally matched 50Ω output stage and an on-chip DC blocking capacitor. This allows direct connection to RF mixers or synthesizers without discrete matching networks or external DC blocks, reducing bill-of-materials count and layout complexity in 2.4GHz ISM-band designs using the MAX2751EUA+T.

What is the shutdown behavior of the MAX2751EUA+T, and how fast does it respond?

The MAX2751EUA+T enters low-power shutdown mode when SHDN (Pin 4) is driven logic-low (≤0.6 V), reducing supply current to less than 1 µA. It exits shutdown and reaches within 3 dB of final output power in 8 µs. This fast response supports duty-cycled protocols like Bluetooth and HomeRF, where rapid oscillator activation and deactivation are required to meet timing constraints without compromising power efficiency in the MAX2751EUA+T.

How is supply noise rejection implemented in the MAX2751EUA+T?

The MAX2751EUA+T uses dual independent supply rails-VCC1 (Pin 5) for the oscillator core and VCC2 (Pin 6) for the output buffer-with separate 220 pF bypass capacitors required for each. This architecture isolates core bias from buffer switching transients, achieving a measured supply pushing of only 1.3 MHz/V. The differential LC oscillator topology further enhances immunity to supply ripple, ensuring stable frequency operation in noisy environments where the MAX2751EUA+T is deployed.

Can the MAX2751EUA+T be used in zero-IF receiver architectures?

No, the MAX2751EUA+T is not intended for zero-IF receiver architectures. Its guaranteed tuning range of 2120–2260 MHz corresponds to a 240–280 MHz IF translation, as stated in the datasheet features. In contrast, zero-IF designs require LO frequencies aligned with the RF band (e.g., 2400–2500 MHz), which is supported by the MAX2750EUA+T-not the MAX2751EUA+T. Using the MAX2751EUA+T in zero-IF would result in incorrect IF placement and degraded demodulation performance.