Analog Devices Inc. HMC851LC3CTR

Overview

HMC851LC3CTR from Analog Devices (formerly Hittite Microwave) is a high-speed CML XOR/XNOR logic gate IC designed for ultra-high-speed serial data path conditioning in test and measurement systems. It supports 28 Gbps data rates and 28 GHz clock frequencies, features programmable differential output voltage swing (500–1300 mV_p-p), 97 ps propagation delay, and on-chip 50 Ω input termination.

For engineers reviewing the HMC851LC3CTR datasheet, HMC851LC3CTR pinout, HMC851LC3CTR application, or HMC851LC3CTR equivalent, key selection considerations include its -3.3 V single-supply operation, VR-controlled output amplitude tuning, sub-100 ps timing precision, and compatibility with AC/DC-coupled 50 Ω systems in RF ATE and broadband serial interconnects.

Technical Context

The HMC851LC3CTR implements true differential CML logic with fully terminated 50 Ω inputs (AP/AN, BP/BN) and current-mode outputs (DP/DN), enabling direct interface to high-speed backplanes and instrumentation without external biasing. Its VR pin provides analog control over differential output swing across process/voltage/temperature, supporting loss compensation in long-channel links.

It operates exclusively from a negative -3.3 V supply (Vee), with all ground pins (GND) and the exposed paddle requiring low-inductance RF grounding. Input return loss exceeds 10 dB below 20 GHz, and output return loss exceeds 10 dB below 18 GHz - critical for signal integrity at 28 Gbps.

Key Specifications

Pinout & Package

Package: 16-lead ceramic SMT (3 × 3 mm, 0.5 mm pitch), alumina body, gold-over-nickel plating, RoHS-compliant, MSL3 rated. Exposed paddle must be soldered to Vee (-3.3 V) for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed logic gate applications.

Compared with HMC851LC3CTR, the HMC852LC3CTR offers integrated dual-channel operation but increases power and reduces per-channel flexibility, while the SY100EL15ZC provides pin-compatible ECL logic at <1/8 the data rate and incompatible supply polarity - neither is a drop-in replacement.

Availability

HMC851LC3CTR is available at Aetrix Electronics and suitable for RF ATE systems, broadband test equipment, and 28 Gbps serial interconnect designs requiring stable component supply, guaranteed traceability, and long-term lifecycle support.

Supply support for HMC851LC3CTR 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 integrates its high-frequency RF and microwave IC portfolio into precision signal chain solutions.

The HMC851LC3CTR belongs to Hittite's HIGH SPEED LOGIC product line, engineered specifically for 25+ Gbps test, measurement, and communications infrastructure where sub-100 ps timing, programmable swing, and CML compatibility are mandatory.

FAQ

What is the recommended power supply configuration for the HMC851LC3CTR?

The HMC851LC3CTR requires a clean, well-decoupled -3.3 V DC supply (Vee) applied to Pin 15 and the exposed paddle. Decoupling capacitors (e.g., 4.7 µF tantalum + 100 pF ceramic) must be placed near the device. Supply tolerance is ±0.3 V; exceeding -3.6 V or -3.0 V violates absolute maximum ratings. The HMC851LC3CTR draws ~73 mA typical, resulting in ~241 mW power dissipation.

How does the VR pin affect the output voltage swing of the HMC851LC3CTR?

The VR pin on the HMC851LC3CTR is an analog control input that adjusts the differential output voltage swing from 500 mV_p-p to 1300 mV_p-p. Applying voltages from -0.4 V to +0.4 V shifts swing linearly - 0 V yields nominal swing (~1090 mV_p-p differential). This enables real-time compensation for channel loss or receiver sensitivity mismatch without hardware changes. The HMC851LC3CTR datasheet provides precise VR vs. swing curves across temperature.

Can the HMC851LC3CTR accept DC-coupled inputs and drive DC-coupled loads?

Yes, the HMC851LC3CTR supports both DC- and AC-coupled operation on all ports. Inputs (AP/AN, BP/BN) feature on-chip 50 Ω termination to ground, allowing direct DC coupling. Outputs (DP/DN) are CML with 50 Ω source impedance and can drive either 50 Ω-to-ground or 50 Ω-to-V_CC loads - DC blocking capacitors are optional when terminating to non-ground DC voltages. This flexibility is confirmed in the HMC851LC3CTR functional description and application circuit.

What is the significance of the 16-lead ceramic 3×3 mm package for the HMC851LC3CTR?

The 16-lead ceramic SMT package (3×3 mm, 0.5 mm pitch) of the HMC851LC3CTR delivers low parasitic inductance and stable RF performance up to 28 GHz. Its alumina body and gold-over-nickel plating ensure reliability under thermal cycling. The exposed paddle must be soldered to Vee for thermal conduction (R_{th j-p} = 59 °C/W) and reference stability. This package enables dense placement in high-frequency test equipment while maintaining signal integrity - a key requirement specified for the HMC851LC3CTR in its outline drawing and package information.

Does the HMC851LC3CTR support both XOR and XNOR logic functions simultaneously?

No - the HMC851LC3CTR implements a single XOR/XNOR function whose output polarity is determined by input signal mapping. As shown in its truth table, applying complementary logic states to inputs A and B yields either XOR (D = A ⊕ B) or XNOR (D = A ⊙ B) behavior. It is not a dual-mode configurable gate; rather, it is a fixed-function gate whose logical output depends on how differential inputs are driven. This behavior is intrinsic to the HMC851LC3CTR's CML topology and verified in its truth table and timing diagram.