Diodes Incorporated ZNBG4000Q16TC

Overview

ZNBG4000Q16TC from Zetex plc is a quad-channel GaAs/HEMT FET bias controller for satellite LNBs and RF front-ends, providing regulated -3 V negative rail generation, individual drain current control per pair (via RCAL1/RCAL2), 2.2 V fixed drain voltage, and dynamic gate voltage limiting (-3.5 V to 0.7 V) - all from a single 5–12 V supply with only two external capacitors.

For engineers reviewing the ZNBG4000Q16TC datasheet, ZNBG4000Q16TC pinout, ZNBG4000Q16TC application, or ZNBG4000Q16TC equivalent, this device delivers stable, temperature-invariant FET biasing in compact QSOP16 packaging with integrated fault protection, RF-stable gate/drain drive, and programmable multi-stage current tuning for noise/gain optimization.

Technical Context

The ZNBG4000Q16TC integrates four independent bias stages sharing a common on-chip oscillator-based negative rail generator (−3 V, ±0.5 V), each driving grounded-source GaAs/HEMT FETs via calibrated gate voltage control. Drain voltage is fixed at 2.2 V (ZNBG4000 variant) with ±0.2 V tolerance over −40°C to +70°C.

Drain current per stage is set externally: RCAL1 configures FETs 1 & 2 (8–12 mA typical), RCAL2 configures FETs 3 & 4 (same range); current stability is ±0.05 %/°C and ±0.02 %/V across supply and temperature. Gate outputs are clamped to −3.5 V to 0.7 V under all transients including power-up/down.

Key Specifications

Pinout & Package

Package: QSOP16 (4.85 mm × 3.90 mm × 1.40 mm body, 0.635 mm pitch, recessed pin 1 marker).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar FET bias controller applications.

Compared with MAX2641 and LMX2594, ZNBG4000Q16TC uniquely integrates quad-channel bias control, on-chip −3 V generation, dual RCAL programming, and hardware FET protection - eliminating 12+ passives and enabling compact, robust LNB designs without compromise on noise or reliability.

Availability

ZNBG4000Q16TC is available at Aetrix Electronics and suitable for satellite receiver LNBs, private mobile radio (PMR) transceivers, and cellular base station receivers requiring stable component supply, RF-grade bias accuracy, and long-term obsolescence resilience.

Supply support for ZNBG4000Q16TC 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

Zetex plc (now part of Diodes Incorporated) was a UK-based analog semiconductor specialist focused on high-performance discrete and analog ICs for RF, power, and signal conditioning applications.

The ZNBG series was designed specifically for GaAs/HEMT FET biasing in satellite and wireless infrastructure - prioritizing RF stability, multi-stage current tuning, and intrinsic FET protection over general-purpose voltage regulation.

FAQ

What external components are mandatory for ZNBG4000Q16TC operation?

Four external components are mandatory: two 47 nF capacitors (CNB and CSUB) for the internal oscillator-based −3 V generator, and two resistors (RCAL1 and RCAL2) to set drain currents for FET pairs 1&2 and 3&4. Optional but recommended are 4.7 nF gate capacitors (CG) and 10 nF drain capacitors (CD) per stage for RF stability.

Can unused bias channels be left unconnected without affecting others?

Yes. Unused drain (DDx) and gate (GDx) pins may be left open-circuit with no impact on remaining active channels. The internal bias circuitry for disconnected stages is automatically disabled. RCAL1 and RCAL2 must still be connected to ground even if only one FET pair is used.

How does the ZNBG4000Q16TC protect external FETs during power-up?

During power-up/down transients, gate outputs are hardware-clamped to −3.5 V to +0.7 V - preventing gate overvoltage that could rupture GaAs/HEMT gate junctions. If the −3 V rail (CSUB) is overloaded or shorted, the device disables all DDx outputs to halt drain current flow before FET thermal runaway occurs.

Is the 2.2 V drain voltage adjustable to match other ZNBG variants?

No. The 2.2 V drain voltage is fixed by internal bandgap and reference circuitry specific to the ZNBG4000/ZNBG6000 family. To obtain 2.0 V drain voltage, the pin-compatible ZNBG4001Q16TC must be used - it shares identical pinout, package, and functional architecture but uses a different internal VD reference.