Diodes Incorporated ZMV933TA

Overview

ZMV933TA from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled oscillator (VCO) and voltage-controlled crystal oscillator (VCXO) tuning circuits. It delivers 42.0 pF capacitance at 1 V, 27.0 pF at 4 V, and minimum Q of 150 at 50 MHz, with reverse leakage as low as 200 pA - enabling ultra-low phase noise in precision frequency synthesis for wireless infrastructure.

For engineers reviewing the ZMV933TA datasheet, ZMV933TA pinout, ZMV933TA application, or ZMV933TA equivalent, key selection criteria include its octave-tuning range (0–6 V), hyperabrupt C-V slope, SOT23 package compatibility, and verified performance in TCXO/VCXO loop filters where capacitance linearity and Q-factor directly impact spectral purity.

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 yields a steep, predictable C-V curve - critical for linear frequency vs. control voltage response in oscillator feedback paths.

Designed for RF tuning up to 50 MHz, it maintains high Q (>150 at 4 V) and low IR (<100 nA at 8 V) across −40°C to +85°C, ensuring stable phase noise floor and minimal temperature-induced drift in timing-critical oscillators.

Key Specifications

Pinout & Package

SOT23-3 surface-mount package: compact 2.67 × 1.20 × 1.10 mm footprint with gull-wing leads, rated for 330 mW power dissipation at 25°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMV1232-011LF and BBY58-02W, ZMV933TA uniquely balances octave tuning (42→12 pF), SOT23 compatibility, and 150-Q baseline - making it optimal for cost-sensitive, medium-pull VCXOs where board space and spectral purity are co-constrained.

Availability

ZMV933TA is available at Aetrix Electronics and suitable for VCXO design, TCXO compensation, wireless baseband VCOs, and pager IF filtering requiring stable component supply across industrial temperature grades and multi-year production cycles.

Supply support for ZMV933TA 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) specialized in high-performance analog and RF discrete semiconductors, with emphasis on low-noise, high-linearity devices for timing and signal conditioning.

ZMV933TA belongs to the ZMV93x hyperabrupt varactor family, engineered specifically for precision frequency control in oscillator loops where C-V linearity, Q-factor, and leakage current directly determine phase noise and tuning accuracy.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

The absolute maximum reverse voltage is 12 V, but Zetex specifies 6 V as the practical upper limit for octave tuning. Operating above 6 V yields diminishing capacitance change and increases risk of accelerated aging due to field-enhanced leakage; sustained bias beyond 8 V is not recommended per Issue 7 datasheet derating guidelines.

Can ZMV933TA be used in series or parallel configurations?

Yes - dual common-cathode variants (e.g., ZMV933ATA) exist for parallel tuning, but ZMV933TA is single-diode. For series use, two units may be placed anode-to-cathode to double effective V_BR, though C_J halves and Q degrades ~15% due to added parasitic inductance; layout symmetry is critical to avoid imbalance.

How does temperature affect its capacitance tuning linearity?

Capacitance exhibits a temperature coefficient of 300–400 ppm/°C, causing ~0.5% C-shift over −40°C to +85°C at fixed bias. This introduces nonlinearity in open-loop VCOs; closed-loop systems (e.g., PLL-based VCXOs) compensate via control voltage adjustment, preserving effective linearity within ±0.1%.

Is the SOT23 pinout compatible with standard PCB footprints for ZMV930–ZMV934 series?

Yes - all ZMV93x variants share identical SOT23-3 mechanical dimensions and pin assignment (Anode-Pin1, Cathode-Pin2, NC-Pin3). The ZMV933TA uses the same land pattern as ZMV930TA through ZMV934TA, enabling drop-in replacement within the series without layout changes.