Diodes Incorporated ZMV934TA

Overview

ZMV934TA from Zetex Semiconductors is a 12 V hyperabrupt silicon varactor diode in SOT-23 package, designed for voltage-controlled frequency tuning in oscillator 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 - enabling ultra-low phase noise in VCXO/TCXO modules for wireless infrastructure.

For engineers reviewing the ZMV934TA datasheet, ZMV934TA pinout, ZMV934TA application, or ZMV934TA equivalent, key selection criteria include its octave-tuning range (0–6 V), hyperabrupt C-V slope, low IR for phase noise criticality, and SOT-23 compatibility with high-density RF layout constraints.

Technical Context

This varactor operates as a voltage-dependent capacitor in resonant tank circuits, where applied reverse bias modulates junction depletion width to shift resonant frequency. Its hyperabrupt doping profile ensures near-linear frequency vs. voltage response over 0–6 V, critical for stable PLL-based synthesizers.

Electrical behavior is characterized at 25°C with VR = 1–4 V; capacitance tolerance is tightly controlled per ZC930/ZMV930/ZV931 series spec, and temperature coefficient is 300–400 ppm/°C at 3 V and 1 MHz - directly impacting thermal drift in precision timing applications.

Key Specifications

Pinout & Package

SOT-23 package: 3-pin surface-mount plastic case with gull-wing leads; cathode marked by beveled edge or dot; standard pin 1 = anode, pin 2 = cathode, pin 3 = unused (isolated die attach pad).

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, ZMV934TA uniquely balances wide 95–25 pF tuning span with adequate Q and ultra-low leakage - making it optimal for VCXO/TCXO designs requiring both octave coverage and sub-–150 dBc/Hz phase noise.

Availability

ZMV934TA is available at Aetrix Electronics and suitable for VCXO modules, TCXO reference oscillators, and wireless transceiver VCOs requiring stable component supply with traceable lot history and extended lifecycle support.

Supply support for ZMV934TA 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 plc was a UK-based designer of high-performance analog and RF semiconductors, acquired by Diodes Incorporated in 2008; legacy Zetex parts maintain industrial-grade reliability and specification consistency.

ZMV934TA belongs to the ZC930/ZMV930/ZV931 series of hyperabrupt varactors engineered specifically for low-phase-noise frequency control in telecom timing systems and portable radio equipment.

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 VCXO circuits, Zetex specifies 8 V as the maximum operating reverse bias. Exceeding 8 V increases reverse leakage exponentially and accelerates junction degradation, particularly above 85°C ambient.

Does ZMV934TA require derating at elevated temperatures?

Yes - reverse leakage current doubles every ~10°C rise above 25°C, and Q degrades by ~15% between 25°C and 85°C. For TCXO use, design must account for 200 pA (25°C) rising to ~1.6 nA (85°C), affecting control voltage stability in high-impedance bias networks.

Can ZMV934TA be used in dual-common-cathode configuration?

No - ZMV934TA is a single-diode device in SOT-23 package. Dual configurations (e.g., ZC934TA) exist in the same series but use SOD-323 and have separate anode terminals; ZMV934TA's pin 3 is a thermal pad, not an electrical terminal.

How does the 300–400 ppm/°C temperature coefficient impact TCXO design?

This coefficient quantifies capacitance drift with temperature at fixed bias, directly translating to frequency drift in crystal-loaded tanks. In a TCXO, it must be actively compensated using thermistor networks or DAC-driven correction voltages to hold total system drift within ±0.1 ppm over –40°C to +85°C.