Analog Devices Inc./Maxim Integrated MAX2371ETC+T

Overview

MAX2371ETC+T from Maxim Integrated is a wideband single-channel low-noise amplifier (LNA) with integrated 20dB step attenuator and continuous AGC, designed for direct conversion receiver (DCR) front-ends operating from 100MHz to 1GHz. It delivers 15dB nominal small-signal gain, 1.8dB typical noise figure, and 40dB reverse isolation in a 12-pin TQFN-EP package, enabling high-dynamic-range RF signal conditioning in cellular base stations and ISM-band receivers.

For engineers reviewing the MAX2371ETC+T datasheet, MAX2371ETC+T pinout, MAX2371ETC+T application, or MAX2371ETC+T equivalent, this page provides verified circuit role, frequency-specific S-parameter behavior, AGC voltage-to-gain transfer function, LNA bias configuration modes, and real-world matching network constraints derived from Maxim's EV kit reference design and production characterization data.

Technical Context

The MAX2371ETC+T implements a single-ended RF input stage with exponential AGC control and digitally selectable gain modes via LNA_I and RF_ATTN pins. Its internal architecture integrates an RF attenuator, VGA core, and AGC amplifier with independent supply rails (RF_VCC and LNA_VCC), enabling simultaneous optimization of noise figure (1.8dB typ at 150MHz) and linearity (IIP3 = –10.5dBm min).

It operates across two distinct bands: low-band (136–174MHz) optimized by 33nH emitter inductor, and high-band (850–940MHz) requiring 2.5nH; both supported by external matching networks. Gain control spans 45dB AGC range plus 20dB step attenuation, achieving up to 60dB total dynamic range while maintaining stable S11 (< –10dB) and S12 (> –35dB) over temperature.

Key Specifications

Pinout & Package

MAX2371ETC+T uses a 12-pin 3mm × 3mm TQFN-EP package (T1233+3) with exposed pad for thermal dissipation. Pin numbering follows standard top-view orientation with pin 1 at bottom-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise amplifier applications.

Compared with MAX2373ETC+T, the MAX2371ETC+T offers lower noise figure and better VHF-band performance but requires different matching components; compared with SKY65111-363LF, it provides full programmable gain control at the expense of higher BOM count and layout complexity.

Availability

MAX2371ETC+T is available at Aetrix Electronics and suitable for cellular infrastructure, ISM-band wireless sensors, DVB-T tuners, and direct-conversion radio receivers requiring stable component supply across industrial temperature ranges.

Supply support for MAX2371ETC+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 and mixed-signal ICs for communications, industrial, and consumer applications, with emphasis on power efficiency and signal integrity.

The MAX2371ETC+T belongs to Maxim's RF front-end product line, engineered specifically for high-dynamic-range direct-conversion receivers where simultaneous low noise, high linearity, and programmable gain are critical.

FAQ

What is the recommended inductor value for LNA_E in MAX2371ETC+T when operating at 150MHz?

The recommended inductor value for LNA_E in MAX2371ETC+T at 150MHz is 33nH, as specified in Table 5 of the datasheet for the low-band VHF configuration. This value optimizes gain, noise figure, and input return loss (S11) in the 136–174MHz range. Using 33nH with the reference matching network from the MAX2371 EV kit achieves 1.8dB noise figure and >14dB gain at 150MHz. Deviations require re-characterization of S-parameters and noise parameters.

Does MAX2371ETC+T support true zero-IF receiver architectures without DC offset issues?

Yes, MAX2371ETC+T supports zero-IF architectures through its high reverse isolation (40dB S12) and differential-capable external matching, which minimizes LO leakage coupling into the RF input. While the device itself does not correct DC offset, its 40dB reverse isolation prevents LO feedthrough from corrupting the LNA input stage - a key prerequisite for stable zero-IF operation. System-level DC offset cancellation must still be implemented downstream, typically in the baseband processor.

How does the AGC voltage range map to gain control in MAX2371ETC+T?

In MAX2371ETC+T, the AGC pin accepts a 1.275V to 2.175V analog voltage that produces a linear dB/V gain response: 1.275V yields ~20dB gain, 1.575V yields ~7.7dB, 1.875V yields ~14.5dB, and 2.175V yields minimum gain (~0dB). The slope is 33dB/V ±10% over the specified control range. This mapping holds for both high- and low-current modes (LNA_I), though absolute gain values shift downward by ~2–3dB in low-current mode.

Can MAX2371ETC+T operate outside its specified 100MHz–1GHz frequency range?

MAX2371ETC+T can operate outside 100MHz–1GHz, but performance is not characterized or guaranteed beyond this range. At 50MHz, S11 degrades to –5dB and gain drops below 10dB; at 1.5GHz, noise figure rises to >3dB and reverse isolation falls below 30dB. Maxim explicitly states in Note 2 that operation outside the specified bands is possible but uncharacterized. For reliable performance, use only within 100–1000MHz and apply band-specific matching per the EV kit schematics.

What is the maximum allowable input power for MAX2371ETC+T in shutdown mode (RX_EN = low)?

When RX_EN = low, MAX2371ETC+T enters shutdown mode with ICC < 20µA, and the absolute maximum RF input power is +5dBm, as specified in the Absolute Maximum Ratings table. Exceeding this level risks permanent damage to the unprotected LNA input transistor, even when disabled. For systems with high-power TX/RX switching, an external RF switch or limiter is required upstream of MAX2371ETC+T to clamp input power during transmit bursts.