Diodes Incorporated ZMV931TC

Overview

ZMV931TC 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 13.5 pF capacitance at 1 V, 6.5 pF at 2.5 V, and 4.0 pF at 4 V reverse bias, with minimum Q of 300 at 50 MHz and typical reverse leakage of 200 pA - enabling low-phase-noise VCXO/TCXO designs for wireless communications.

For engineers reviewing the ZMV931TC datasheet, ZMV931TC pinout, ZMV931TC application, or ZMV931TC equivalent, key selection criteria include its octave-tuning range (0–6 V), tight C-V tolerance, high Q at RF frequencies, low IR for phase noise sensitivity, and SOT-23 compatibility with automated SMT assembly in timing modules and mobile radio front-ends.

Technical Context

This hyperabrupt junction varactor exhibits a steep, predictable capacitance-voltage curve optimized for wide-range linearized frequency control. Its C-V profile supports octave tuning from 0 to 6 V, with capacitance varying from ~13.5 pF down to ~2.9 pF across that range.

Designed for RF resonance stabilization, it achieves Q ≥ 300 at 50 MHz and 4 V bias, while maintaining IR ≤ 100 nA at 8 V - critical for minimizing oscillator phase noise in TCXOs and VCOs used in pagers and narrowband mobile radios.

Key Specifications

Pinout & Package

SOT-23 package: 3-pin surface-mount plastic case with gull-wing leads; cathode marked by band; standard JEDEC MO-215 outline; footprint compatible with automated pick-and-place and reflow.

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, ZMV931TC uniquely balances octave tuning (13.5 → 4.0 pF), Q ≥ 300, and SOT-23 manufacturability - making it optimal for mid-band (300–900 MHz) VCXOs where both range and noise matter.

Availability

ZMV931TC is available at Aetrix Electronics and suitable for VCXO design, TCXO manufacturing, and mobile radio VCO development requiring stable component supply and traceable lot history.

Supply support for ZMV931TC 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 discretes, with emphasis on low-noise, high-reliability silicon solutions for timing and signal conditioning.

The ZMV931TC belongs to Zetex's hyperabrupt varactor series engineered specifically for precision frequency control in communication-grade oscillators - prioritizing C-V linearity, Q consistency, and leakage-limited phase noise.

FAQ

What is the recommended DC blocking configuration when using ZMV931TC in a VCO?

A series 100 Ω resistor and 100 pF ceramic capacitor between the tuning voltage source and anode (Pin 1) is standard. This isolates RF from the control line while allowing sufficient tuning speed for PLL loop bandwidths up to 10 kHz. The resistor also limits surge current during power-up.

Can ZMV931TC be used in series-tuned VCO topologies?

No - ZMV931TC is specified and characterized only for shunt-connected (reverse-biased) operation in parallel-resonant tank circuits. Its hyperabrupt profile and Q rating assume cathode-grounded configuration; series use would violate bias conditions and invalidate C-V/Q specs.

Is the SOT-23 pinout compatible with ZMV930TA or ZMV932TA?

Yes - all ZMV9xxTA variants share identical SOT-23 pinout (anode/cathode/NC), package dimensions, and thermal characteristics. Only capacitance values and C-V slopes differ; they are drop-in replacements for layout reuse across tuning range adjustments.

How does temperature affect the C-V curve of ZMV931TC?

Capacitance decreases ~350 ppm/°C across –40°C to +85°C at fixed bias. At 3 V, C shifts from 5.8 pF (–40°C) to 5.4 pF (+85°C). This drift is compensated in TCXOs via thermistor networks or digital calibration algorithms using the published tempco value.