Analog Devices Inc. HMC980LP4E

Overview

HMC980LP4E from Analog Devices is a high-current active bias controller IC designed to automatically regulate gate voltage for RF power amplifiers, supporting drain currents up to 1.6 A and drain supply voltages from 5 V to 16.5 V. It integrates an internal negative voltage generator (−2.46 V), dual gate control (VGATE and VG2), and over/undercurrent alarm with hysteresis - enabling stable Class A amplifier biasing in microwave radio, VSAT, and cellular base station applications.

For engineers reviewing the HMC980LP4E datasheet, HMC980LP4E pinout, HMC980LP4E application, or HMC980LP4E equivalent, key selection considerations include its 24-lead 4 mm × 4 mm LFCSP package, adjustable R_{DS_ON} via S0/S1 logic inputs, ±4 mA VGATE sink/source capability, TRIGOUT daisy-chain signaling, and precise drain current set accuracy using external ISENSE resistor networks.

Technical Context

The HMC980LP4E implements a closed-loop analog feedback system that continuously adjusts VGATE to maintain constant IDRAIN despite supply, temperature, and process variations - eliminating factory calibration. Its internal MOSFET switch between VDD and VDRAIN enables safe power-up sequencing: VGATE is pulled to VNEG before VDRAIN is applied, ensuring the external amplifier remains fully pinched off during startup.

It features dual-domain operation: a high-voltage domain (VDD: 5–16.5 V) powers the output stage and RF amplifier supply path, while a low-voltage digital domain (VDIG: 3.3–5 V) powers logic, reference, and control circuitry. The integrated charge pump (300 kHz) generates VNEG for depletion-mode biasing, and VG2 provides a fixed secondary gate voltage adjustable via VG2_CONT resistor divider.

Key Specifications

Pinout & Package

Package: 24-lead, 4 mm × 4 mm LFCSP (HCP-24-21), RoHS-compliant, with exposed thermal pad (EPAD) for enhanced heat dissipation (θ_JA = 49.4°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar active RF amplifier biasing applications.

Compared with LM3478MM/NOPB and MAX2034ETA+T, the HMC980LP4E uniquely combines 1.6 A closed-loop current regulation, integrated −2.46 V generation, dual-gate outputs, and hardware daisy-chain triggering - making it the only solution qualified for high-power, multi-stage, depletion-mode RF amplifier biasing in microwave infrastructure.

Availability

HMC980LP4E is available at Aetrix Electronics and suitable for microwave radio, VSAT terminal, and cellular base station applications requiring stable component supply, long-term lifecycle continuity, and traceable sourcing for RF power amplifier subsystems.

Supply support for HMC980LP4E 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 communications, industrial, and aerospace markets with precision signal processing solutions.

The HMC980LP4E belongs to Analog Devices' Hittite Microwave product line, engineered specifically for high-reliability RF power amplifier biasing in microwave infrastructure - emphasizing thermal robustness, sequencing safety, and calibration-free operation.

FAQ

What is the maximum drain current supported by the HMC980LP4E?

The HMC980LP4E supports adjustable drain current up to 1.6 A, achieved when both S0 and S1 pins are driven to VDIG. This maximum is validated across the full operating temperature range (−40°C to +85°C) and requires appropriate PCB thermal design due to power dissipation. At 1.6 A, the internal MOSFET's R_{DS_ON} is 0.7 Ω, resulting in ~1.12 W conduction loss - necessitating use of the exposed EPAD for thermal management.

How does the HMC980LP4E handle power-up sequencing for RF amplifiers?

The HMC980LP4E enforces strict hardware-based power-up sequencing: first pulling VGATE to VNEG to pinch off the amplifier, then enabling VDRAIN, followed by VG2 activation, and finally ramping VGATE to achieve target IDRAIN. This sequence prevents destructive current surges during startup. The TRIGOUT pin signals completion of this sequence, enabling cascaded devices to begin their own startup only after stabilization.

Can the HMC980LP4E bias both enhancement-mode and depletion-mode RF amplifiers?

Yes - the HMC980LP4E supports both amplifier types. For depletion-mode devices, VNEGFB is left floating to enable the internal −2.46 V generator, and VGATEFB is also left floating. For enhancement-mode devices, VNEGFB is grounded to disable the charge pump, and VGATEFB is shorted to ground to configure the threshold. This dual-mode flexibility is confirmed in the Functional Block Diagram and General Description sections of the Rev. C datasheet.

What is the role of the FIXBIAS pin on the HMC980LP4E?

The FIXBIAS pin requires connection of a precision 10 kΩ resistor (0.5% tolerance, ±25 ppm/°C TCR) to ground to ensure optimal bias accuracy and minimize offset errors in the current-sense amplifier. Omitting this resistor or using non-precision components degrades IDRAIN regulation accuracy beyond the specified 0.023%/°C drift, directly impacting RF amplifier linearity and gain stability.

Does the HMC980LP4E provide protection against short-circuit faults?

Yes - the HMC980LP4E includes self-protection circuitry that detects short circuits on VDRAIN or VNEG. Upon detection, it immediately disables VDRAIN and VGATE outputs and pulls VGATE to VNEG to safely shut down the amplifier. Recovery requires either a full power cycle or toggling the EN pin; the device remains latched in fault mode until reset, preventing automatic re-engagement into a hazardous condition.