2000nH Broadband Inductors Ultra Wideband Microwave Inductor 10MHz - 40GHz

Product Overview

The HALT68005 is a broadband conical inductor for millimeter-wave RF bias networks and high-speed optoelectronics operating from 10 MHz to 40 GHz. It delivers 2000 nH (2.0 µH) of nominal inductance—the highest in the broadband conical inductor product series—with a ±20% tolerance at 10 MHz. The component is wound with 0.05 mm (50 µm) ultra-fine oxygen-free copper wire in a continuously tapered conical geometry, rated for 200 mA continuous DC current across -55°C to +125°C.

A standard solenoid with 2000 nH of inductance would self-resonate below 500 MHz due to concentrated inter-turn parasitic capacitance. The HALT68005 overcomes this through its tapered conical architecture: turn diameter increases continuously from a narrow ~0.40 mm OD at the apex to a wider base, distributing parasitic capacitance across a mechanical gradient rather than concentrating it at a single LC product. The result is a flat, resonance-free high-impedance response spanning 10 MHz to 40 GHz—a frequency ratio of 4000:1 in a single 3.0 mm component.

An optional 0.08 mm wire configuration is available on custom order for applications requiring higher DC current at reduced upper bandwidth. The air-core construction eliminates magnetic saturation, maintaining the full 2000 nH inductance across the 0–200 mA DC range. Each unit is fixture-characterized: .s2p Touchstone data (10 MHz–40 GHz, 201 points, TRL-de-embedded to the component lead reference plane) is available for direct import into RF circuit simulators.

Complete Technical Specifications

How the Conical Geometry Enables 4000:1 Bandwidth

Achieving continuous operation from 10 MHz to 40 GHz requires solving two opposing physical constraints simultaneously. The 2000 nH inductance needed for 10 MHz blocking demands a high turn count, which naturally increases inter-turn parasitic capacitance and lowers the self-resonant frequency. The 40 GHz upper limit demands minimal capacitance, which favors fewer turns and lower inductance.

The conical winding resolves this trade-off through spatial separation of the low-frequency and high-frequency functions:

• Apex (Narrow End, ~0.40 mm OD): The first turns, with the smallest diameter, connect to the 50-Ω microstrip line. Their minimal facing surface area between adjacent turns produces negligible shunt capacitance at the signal junction. This preserves the millimeter-wave transmission path through 40 GHz.
• Mid-Body Taper: Turn diameter increases progressively along the 3.0 mm winding length. Each turn contributes capacitance proportional to its diameter, but the values are distributed rather than summed at one electrical node.
• Base (Wide End): The final turns, with the largest diameter, pack the bulk of the 2000 nH inductance for low-frequency blocking. Their contribution to parasitic capacitance is physically distant from the RF junction, isolated by the tapered impedance transition.

The result is a component whose effective SRF exceeds 40.0 GHz—limited by the test fixture parasitics, not the winding itself—while maintaining 2000 nH of blocking inductance at the low-frequency end.

Multi-Frequency Operational Performance

Each unit undergoes VNA characterization on a calibrated millimeter-wave microstrip fixture with TRL de-embedding:

Key Performance Advantages

• Extreme Broadband Range (10 MHz – 40 GHz): Provides continuous, flat RF isolation from low MHz to millimeter-wave frequencies, replacing multiple cascaded inductors in a single component.
• 0.05 mm Ultra-Fine Wire Winding: Wound with 50 µm copper wire to achieve 2000 nH while maintaining an ultra-compact 3.0 mm footprint with minimal parasitic capacitance for 40 GHz operation.
• Eliminates Cascade Resonances: Single-component solution suppresses signal dips and phase distortions caused by multi-stage inductor biasing.
• Air-Core Saturation Protection: Prevents magnetic saturation at high current levels, ensuring inductance stability and high-Q performance under varying temperature and DC bias.
• Solderable Flying Leads: Standard gold/tin-plated copper flying leads on both ends for integration onto microwave and millimeter-wave microstrip circuits.

Comparative Analysis: HALT68005 vs. HALT60005

Assembly Guidelines

1. Orientation: Small end (cone tip) perpendicular (≈90°) to the RF transmission microstrip line. Off-perpendicular mounting degrades S11 above 20 GHz.
2. Lead Trim: Keep the apex flying lead between solder fillet and first turn ≤0.3 mm. At 40 GHz, even a 0.5 mm lead wire acts as a significant parasitic inductor, introducing unwanted reflection and signal degradation.
3. Base Connection: Solder wide end to DC bias pad. Place bypass capacitors within 1 mm to minimize inductive loop between choke and ground.
4. Epoxy Fixation (mandatory): Apply a micro-dot of non-conductive, low-outgassing epoxy (Epotek H70E or H65) on the winding side. This prevents resonant microphonic vibrations under mechanical excitation.
5. Soldering: Controlled micro-soldering tip temperature 280–320°C for ≤2 seconds per joint. The 0.05 mm wire reaches soldering temperature almost instantly; prolonged heating anneals the copper and alters the precision taper. Compatible with SAC305, AuSn eutectic, and PbSn solder alloys.

Applications

• 40 Gbps / 100 Gbps optical transceiver bias tees (TOSA/ROSA)
• 5G NR FR2 (28 GHz / 39 GHz) phased-array antenna element DC distribution
• Ka-band satellite communication transponder bias networks
• Millimeter-wave VNA frequency extender bias tees
• Automotive radar (77 GHz) bias network decoupling
• High-speed photodiode reverse-bias decoupling in coherent receivers

Frequently Asked Questions

Q: Why is a single 2000 nH conical inductor preferred over cascading multiple inductors?
A: Cascading a large-value inductor with a small-value inductor creates a parasitic LC circuit at their junction, introducing a sharp resonant dip in the microwave band. The HALT68005 combines 2000 nH inductance with a tapered conical architecture, achieving continuous, resonance-free isolation from 10 MHz to 40 GHz in a single component with no junction parasitics.

Q: Is the 0.05 mm wire durable enough for strategic-grade high-vibration environments?
A: While a 0.05 mm wire is extremely delicate, the low mass of the air-core conical coil reduces its susceptibility to mechanical shock. When properly secured with a micro-dot of low-outgassing epoxy on the side of the winding, the assembly passes strategic-grade vibration and mechanical shock tests (MIL-STD-202, Method 204 & 213). There is no ferrite core to crack from CTE mismatch.

Q: Why is the upper frequency limit rated at 40 GHz?
A: The 40 GHz rating is achieved through the 0.05 mm ultra-fine wire, which minimizes capacitive coupling between winding turns to the practical minimum. This allows the inductor to maintain its inductive high-impedance state without entering parallel resonance, ensuring continuous shielding to 40.0 GHz. Above this frequency, pad parasitics and fixture limitations dominate the apparent response rather than the winding itself.