Analog Devices Inc. DC2310A

Overview

LTC5549 from Analog Devices (formerly Linear Technology) is a 2GHz–14GHz passive double-balanced microwave mixer with integrated LO buffer and digitally controllable frequency doubler. It supports upconversion and downconversion, delivers +28.2dBm IIP3 at 5.8GHz, 8.0dB conversion loss at 5.8GHz, and operates with only 0dBm LO drive - enabling use in C/X/Ku-band radar and wireless backhaul transceivers.

For engineers reviewing the LTC5549 datasheet, LTC5549 pinout, LTC5549 application, or LTC5549 equivalent, key selection considerations include its 12-lead 2mm × 3mm QFN package, CMOS-compatible X2/EN control pins, LO doubler enable capability, and verified performance across –40°C to 105°C case temperature with 3.3V/115mA supply.

Technical Context

The LTC5549 integrates a high-linearity passive mixer core, single-ended LO buffer amplifier (1–12GHz), and bypassable frequency doubler controlled by the X2 pin. Its RF, LO, and IF ports are all 50Ω single-ended with internal transformer coupling and require DC blocking capacitors.

It supports both low-side and high-side LO injection, offers fast 0.2μs turn-on/0.1μs turn-off for TDD operation, and maintains broadband impedance match (RF: 2–14GHz, LO: 1–12GHz, IF: 0.5–6GHz) when driven with –6 to +6dBm LO power.

Key Specifications

Pinout & Package

Package: 12-lead (2mm × 3mm) plastic QFN (UDB), exposed thermal pad (Pin 13) soldered to PCB ground for electrical and thermal integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with HMC1040LP3DE and QPC1006, the LTC5549 uniquely combines integrated LO buffering, digital doubler control, and low-power 3.3V operation in a miniature QFN - making it optimal for compact, thermally constrained, and synthesizer-limited microwave systems where ease of integration outweighs absolute NF or bandwidth extremes.

Availability

LTC5549 is available at Aetrix Electronics and suitable for wireless backhaul, phased-array antennas, and C/X/Ku band radar systems requiring stable component supply, extended temperature support (–40°C to 105°C), and repeatable RF performance across production lots.

Supply support for LTC5549 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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and RF ICs, formed through the acquisition of Linear Technology in 2017.

The LTC5549 belongs to ADI's high-frequency mixer product line, designed specifically for microwave communication and sensing systems demanding wide bandwidth, high linearity, and simplified LO interface - especially where space, power, and synthesizer compatibility are critical constraints.

FAQ

What is the function of the X2 pin on the LTC5549?

The X2 pin on the LTC5549 is a CMOS-compatible digital control input that enables or disables the internal LO frequency doubler. When X2 voltage exceeds 1.2V, the doubler activates - allowing the LO port to accept half the target frequency (e.g., 1.955GHz to generate 3.91GHz RF). When X2 is below 0.3V, the doubler is bypassed. The LTC5549 uses an internal 376kΩ pull-down resistor, so an unconnected X2 defaults to doubler-off mode.

Does the LTC5549 require external matching components?

The LTC5549 achieves 50Ω matching across its full RF (2–14GHz), LO (1–12GHz), and IF (0.5–6GHz) bands only with specified external shunt capacitors: 0.15pF at 1.4mm from the RF pin (C1) and 0.15pF at 3.55mm from the LO pin (C4). Without these, RF match degrades above 10GHz and LO match above 8.4GHz. The LTC5549 does not require baluns or transformers - its internal single-ended architecture eliminates them.

Can the LTC5549 be used for both upconversion and downconversion?

Yes, the LTC5549 supports bidirectional operation: as a downconverter (RF in → IF out) or upconverter (IF in → RF out), with either low-side or high-side LO injection. Its symmetric architecture and broadband ports allow flexible signal routing - for example, applying 1.6–4.5GHz to the RF port and extracting 5.2GHz at the IF port, as validated in the datasheet's Figure 11. All AC specifications (IIP3, conversion loss, P1dB) are characterized for both modes.

What is the maximum RF input power the LTC5549 can handle?

The LTC5549 has an absolute maximum RF input power rating of +20dBm (100mW) across its 2–14GHz band. However, for linear operation, the datasheet specifies +14.3dBm input P1dB at 5.8GHz - meaning compression begins near this level. Sustained operation above +15dBm risks distortion and reduced dynamic range. The LTC5549's robustness is enhanced by internal DC-grounded transformer primaries (≈3.2Ω RF, ≈6.2Ω IF), but DC blocking capacitors remain mandatory if source DC voltage is present.

How does temperature affect conversion loss in the LTC5549?

Conversion loss in the LTC5549 exhibits excellent thermal stability: its typical drift is only 0.009dB/°C over –40°C to 105°C case temperature, measured at 5.8GHz. This low sensitivity ensures consistent gain budgeting across environmental extremes - critical for outdoor radar and aerospace applications. The LTC5549's performance curves (Figures G04, G18, G27, G36) confirm minimal variation in both conversion loss and IIP3 across the full temperature range under fixed LO/IF conditions.