Diodes Incorporated ZC932TA

Overview

ZC932TA from Zetex Semiconductors is a 12 V hyperabrupt silicon varactor diode in SOT23 package, optimized for voltage-controlled oscillator (VCO) and temperature-compensated crystal oscillator (TCXO) tuning circuits. It delivers 17.0 pF capacitance at 1 V, 8.5 pF at 2.5 V, and 5.5 pF at 4 V reverse bias, with minimum Q of 200 at 50 MHz and typical reverse leakage of 200 pA - enabling low-phase-noise frequency synthesis in wireless transceivers.

For engineers reviewing the ZC932TA datasheet, ZC932TA pinout, ZC932TA application, or ZC932TA equivalent, key selection criteria include its octave-tuning range (0–6 V), tight C-V tolerance, high Q at RF frequencies, and compatibility with miniature SMT oscillator designs requiring stable capacitance slope and minimal leakage-induced noise.

Technical Context

The ZC932TA employs a hyperabrupt junction profile to achieve a near-linear frequency vs. voltage relationship in VCOs, supporting octave-range tuning from 0 to 6 V. Its capacitance varies from 17.0 pF (VR = 1 V) to 5.5 pF (VR = 4 V), with a temperature coefficient of 300–400 ppm/°C at 3 V and 1 MHz.

Designed for RF tuning applications, it operates within absolute maximum ratings of 12 V reverse voltage and 100 mA forward current, with power dissipation limited to 330 mW in SOT23. Low IR (≤100 nA at VR = 8 V) ensures minimal phase noise degradation in sensitive oscillator loops.

Key Specifications

Pinout & Package

Supplied in SOT23 package (JEDEC TO-236AB), 3-terminal surface-mount device with anode, cathode, and case (cathode-connected case). Dimensions: 2.67–3.05 mm length × 1.20–1.40 mm width × 0.95 mm height.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMV1232-011LF and BBY52-02W, ZC932TA offers optimal balance of SOT23 footprint, 17–5.5 pF tuning span, and 200 pA leakage - making it preferred for space-constrained, low-phase-noise TCXO and VCXO designs where C–V linearity and thermal stability are critical.

Availability

ZC932TA is available at Aetrix Electronics and suitable for VCXO modules, TCXO timing subsystems, and mobile radio VCOs requiring stable component supply, lot-to-lot C–V consistency, and low-phase-noise performance.

Supply support for ZC932TA 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 precision discrete devices for timing, signal conditioning, and power management.

The ZC930–ZC934 series was developed specifically for voltage-controlled frequency synthesis in communications infrastructure, delivering hyperabrupt C–V characteristics and ultra-low leakage in miniature SMT packages for oscillator designers.

FAQ

What is the recommended PCB pad layout for ZC932TA in SOT23?

Use JEDEC standard SOT23 footprint: 1.5 mm × 1.3 mm pad length, 0.5 mm pad width, 0.95 mm center-to-center pitch. Ground the cathode pad (Pin 2 & 3) with ≥2 thermal vias to inner ground plane to minimize inductance and stabilize RF impedance. Avoid soldermask-defined pads to ensure consistent C–V repeatability.

Can ZC932TA be used in series-tuned VCO configurations?

Yes - ZC932TA supports both shunt-tuned (parallel-resonant) and series-tuned (series-resonant) VCO topologies. Its hyperabrupt profile maintains monotonic C–V slope down to 0 V, enabling stable series resonance tracking. Verify Q remains >150 at operating frequency using measured S-parameters, not just 50 MHz spec.

Is ZC932TA RoHS compliant and halogen-free?

Yes - ZC932TA conforms to RoHS Directive 2011/65/EU and is halogen-free per IEC 61249-2-21. The SOT23 package uses matte tin lead finish (Sn), and the die passivation meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL1) for unlimited floor life at ≤30°C/60% RH.

How does temperature affect ZC932TA's capacitance tuning slope?

At 3 V bias and 1 MHz, ZC932TA exhibits a temperature coefficient of 300–400 ppm/°C. This means capacitance shifts by ~0.3–0.4% per °C, causing measurable VCO frequency drift. For TCXO use, this slope must be compensated using NTC thermistors or digital lookup tables calibrated across −40°C to +85°C.