Diodes Incorporated ZC836ATA

Overview

ZC836ATA from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators. It delivers 100 pF nominal capacitance at 2 V, 5.0–6.5 capacitance ratio (C₂/C₂₀), ≥100 Q at 50 MHz, <20 nA reverse leakage at 20 V, and operates up to +150°C - enabling low-phase-noise VCXO/TCXO designs in wireless infrastructure and mobile radio front-ends.

For engineers reviewing the ZC836ATA datasheet, ZC836ATA pinout, ZC836ATA application, or ZC836ATA equivalent, key selection criteria include its hyperabrupt CV slope for steep tuning response, SOT23 package compatibility with high-density RF layouts, 25 V reverse breakdown rating, and guaranteed 100 pF ±10% tolerance at 2 V - critical for stable oscillator center-frequency calibration and temperature-compensated loop design.

Technical Context

The ZC836ATA implements a hyperabrupt junction profile to achieve a steep, linearized C–V response ideal for narrowband VCOs and TCXOs requiring high tuning sensitivity. Its capacitance varies from ~110 pF at 2 V to ~17 pF at 20 V, yielding a measured C₂/C₂₀ ratio of 5.0–6.5 at 1 MHz.

Designed for RF bias networks, it maintains Q ≥100 at 50 MHz under 3 V reverse bias and exhibits ≤20 nA IR at 20 V - directly supporting ultra-low phase noise performance in oscillator tank circuits where leakage-induced drift and thermal instability must be minimized.

Key Specifications

Pinout & Package

The ZC836ATA is housed in an industry-standard SOT23 plastic package with cathode-marked pin 1. The device is a single-anode, common-cathode varactor - pin 1 is cathode, pin 2 is anode, and pin 3 is unused (internal die attach).

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, the ZC836ATA offers the best balance of tuning linearity (C₂/C₂₀ = 5.0–6.5), ultra-low leakage (<20 nA), and SOT23 thermal robustness - making it preferred for production-grade VCXOs where long-term stability and manufacturability are prioritized over marginal Q gain.

Availability

ZC836ATA is available at Aetrix Electronics and suitable for VCXO calibration, TCXO compensation, and mobile radio VCO tuning requiring stable component supply, tight CV matching, and RoHS-compliant SMT assembly.

Supply support for ZC836ATA 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) was a UK-based ISO 9001/TS16949-certified manufacturer specializing in high-performance analog and RF discrete semiconductors.

The 830 series varactors were engineered specifically for frequency control in telecom and wireless infrastructure - emphasizing hyperabrupt CV linearity, low phase noise, and high-temperature reliability in oscillator and filter tuning applications.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

The ZC836ATA has a 25 V reverse breakdown rating and is rated for continuous operation up to 20 V reverse bias. Operating above 20 V increases leakage exponentially and risks irreversible junction degradation; derating to 15 V is advised for 15-year field reliability in telecom equipment.

Does ZC836ATA require special PCB layout considerations for RF performance?

Yes - minimize trace length between pins 1 and 2, use solid ground plane beneath the SOT23 footprint, and avoid routing high-impedance tuning lines parallel to RF traces. Keep DC bias filtering capacitors within 2 mm of pin 2 to suppress supply noise coupling into the VCO tank.

Is the SOT23 package lead-free and RoHS compliant?

Yes - per Zetex's Green Compliance statement in Issue 11 (January 2007), all 830 series devices including ZC836ATA meet EU RoHS Directive 2002/95/EC requirements, with lead-free terminations and halogen-free molding compound verified per IEC 62321 testing protocols.

How does temperature affect capacitance stability in ZC836ATA?

The ZC836ATA exhibits a temperature coefficient of 300–400 ppm/°C, meaning capacitance shifts by ~0.03–0.04% per °C. At 2 V bias, this translates to ±0.3–0.4 pF drift over −40°C to +85°C - acceptable for TCXO compensation when paired with NPO/COG trim caps and digital calibration lookup tables.