Diodes Incorporated ZMV934TC

Overview

ZMV934TC from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled oscillator (VCO) and temperature-compensated crystal oscillator (TCXO) tuning circuits. It delivers 95.0 pF capacitance at 1 V, 40.0 pF at 2.5 V, and 25.0 pF at 4 V reverse bias, with minimum Q of 80 at 50 MHz and typical reverse leakage of 200 pA at 8 V - enabling ultra-low phase noise in precision frequency synthesis applications.

For engineers reviewing the ZMV934TC datasheet, ZMV934TC pinout, ZMV934TC application, or ZMV934TC equivalent, key selection criteria include its octave-tuning range (0–6 V), hyperabrupt C-V profile, SOT23 package compatibility, and verified performance in VCXO/TCXO loop filters where low IR and high Q directly impact spectral purity.

Technical Context

This varactor operates as a voltage-dependent capacitor in RF feedback paths, where its hyperabrupt doping profile ensures near-linear frequency vs. control voltage response across 0–6 V. Its 12 V maximum reverse voltage rating and 330 mW power dissipation (SOT23) support robust operation in temperature-stable oscillator topologies.

Capacitance variation is tightly controlled: temperature coefficient is 300–400 ppm/°C at 3 V and 1 MHz, and reverse leakage remains ≤100 nA at 8 V - critical for minimizing drift and phase noise in closed-loop frequency control systems.

Key Specifications

Pinout & Package

SOT23 package: 3-pin surface-mount outline with cathode-marked lead (Pin 1 = anode, Pin 2 = cathode, Pin 3 = NC or unused; confirmed per Zetex SOT23 varactor standard pinout for ZMV series).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar varactor diode applications.

Compared with SMV1232-011 and BBY52-02W, ZMV934TC uniquely balances wide 95–25 pF tuning range, SOT23 manufacturability, and verified 200 pA leakage - making it optimal for cost-sensitive, medium-pull VCXOs where board space and phase noise are co-constrained.

Availability

ZMV934TC is available at Aetrix Electronics and suitable for VCXO design, TCXO manufacturing, and wireless transceiver development requiring stable component supply, consistent C-V matching, and RoHS-compliant SMT assembly.

Supply support for ZMV934TC 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 Semiconductors (now part of Diodes Incorporated) is a UK-based designer of high-performance analog and RF semiconductors, specializing in discrete devices for signal integrity and precision timing.

The ZMV930/ZMV934 series targets frequency control applications, engineered specifically for low-phase-noise oscillator tuning where hyperabrupt C-V linearity and sub-nA leakage are mandatory.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

The absolute maximum reverse voltage is 12 V, but for reliable long-term operation in temperature-stable oscillators, Zetex specifies derated use at ≤8 V to maintain leakage below 100 nA and minimize capacitance drift. Operation above 10 V increases risk of parametric shift after thermal cycling.

Does ZMV934TC require a series current-limiting resistor in VCO bias networks?

Yes - a minimum 100 kΩ resistor is required between the tuning voltage source and Pin 1 (anode) to limit DC current to <100 nA, preventing forward conduction and ensuring stable C-V behavior. Lower resistance values cause measurable capacitance hysteresis and increased phase noise.

Is the SOT23 package lead-free and RoHS compliant?

Yes - ZMV934TC (TA/TC reel codes) uses matte tin-plated leads and complies with EU RoHS Directive 2011/65/EU and China RoHS GB/T 26572–2011. The device carries the "Pb-Free" marking on tape-and-reel packaging and meets JEDEC J-STD-020D reflow profiles for lead-free soldering.

How does temperature affect capacitance tuning accuracy?

At 3 V bias and 1 MHz, capacitance varies by 300–400 ppm/°C. Over –40°C to +85°C, this results in ±5% total capacitance shift - requiring either temperature-sensing compensation or use within narrow ambient ranges. Data sheet Figure 5 confirms monotonic drift with no inflection points.