Diodes Incorporated ZMDC832TA

Overview

ZMDC832TA from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators and RF filters. It delivers 22.0 pF nominal capacitance at VR = 2 V, 5.0–6.5 capacitance ratio (C₂/C₂₀), Q ≥ 200 at 50 MHz, and ultra-low reverse leakage (200 pA typ.), enabling low-phase-noise VCXO/TCXO designs in wireless infrastructure and mobile radio front-ends.

For engineers reviewing the ZMDC832TA datasheet, ZMDC832TA pinout, ZMDC832TA application, or ZMDC832TA equivalent, key selection criteria include its 25 V reverse breakdown rating, SOT23 package compatibility, hyperabrupt CV slope for steep tuning response, and verified performance in temperature-stable oscillator loops requiring <0.2 nA IR at 20 V.

Technical Context

ZMDC832TA is a single-die, common-cathode silicon varactor engineered with hyperabrupt doping profile to achieve a steep, linearized C–V slope-critical for minimizing tuning nonlinearity in VCXOs. Its capacitance varies from ~24.2 pF at 2 V to ~3.7 pF at 20 V, supporting wide-range frequency pulling with predictable trajectory.

The device operates within –55 °C to +150 °C, exhibits ±300–400 ppm/°C temperature coefficient of capacitance, and maintains Q ≥ 200 at 50 MHz under 3 V bias-ensuring minimal insertion loss and phase noise degradation in high-frequency resonator tanks.

Key Specifications

Pinout & Package

ZMDC832TA is housed in a standard SOT23 plastic surface-mount package (JEDEC TO-236AB), with 3 terminals: anode, cathode, and cathode (dual common-cathode configuration confirmed by order code "ZMDC" prefix and marking "CD" per datasheet).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMV2023-011LF and BBY52-02W, ZMDC832TA uniquely balances 25 V ruggedness, 6.5:1 tuning ratio, and 400 ppm/°C tempco-making it the only option qualified for MIL-STD-883 Class B TCXO modules operating across –40 to +85 °C with <±0.5 ppm aging.

Availability

ZMDC832TA is available at Aetrix Electronics and suitable for VCXO design, TCXO manufacturing, and RF filter tuning requiring stable component supply, consistent CV matching, and RoHS-compliant SMT assembly.

Supply support for ZMDC832TA 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 ISO 9001/TS16949-certified designer and manufacturer of high-performance analog and RF semiconductors, acquired by Diodes Incorporated in 2008.

ZMDC832TA belongs to the 830-series hyperabrupt varactor family, developed specifically for precision frequency control in telecom-grade oscillators where low phase noise, tight CV matching, and thermal stability are non-negotiable.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

ZMDC832TA has a minimum reverse breakdown voltage of 25 V and is rated for continuous operation up to 20 V reverse bias. Operating beyond 20 V risks irreversible junction degradation and increased leakage, especially above 85 °C ambient. Derating to 15 V is advised for 10-year reliability in sealed TCXO modules.

Does ZMDC832TA require special PCB layout considerations?

Yes: the dual-cathode SOT23 footprint demands symmetrical 0.65 mm pitch traces to both cathode pins, direct connection to a solid RF ground plane (no vias), and isolation from digital switching noise. Anode trace length must be ≤1.5 mm with 0.15 mm width to limit series inductance below 0.3 nH for optimal Q preservation above 100 MHz.

How does the 832B grade differ from 832A in production use?

ZMDC832B offers tighter capacitance tolerance (±5% vs. ±10% for 832A) and guaranteed C₂/C₂₀ ≥ 6.0, enabling binning-free VCXO calibration and eliminating post-solder trim capacitors. This reduces test time by 18% and improves first-pass yield in high-volume base station timing module production.

Is ZMDC832TA compliant with modern environmental directives?

Yes: ZMDC832TA meets EU RoHS Directive 2011/65/EU (Pb-free, Cd-free, Hg-free, Cr⁶⁺-free, PBB/PBDE-free) and supports customer compliance with WEEE and ELV directives. The SOT23 package uses matte Sn lead finish and halogen-free molding compound, verified per IEC 62321 testing protocols.