Diodes Incorporated ZDC833ATC

Overview

ZDC833ATC from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators. It delivers 33.0 pF nominal capacitance at 2 V, 5.0–6.5 capacitance ratio (C₂/C₂₀), and ultra-low reverse leakage (200 pA typ.) to minimize phase noise in VCXO/TCXO circuits. Its SOT23 package supports high-density RF filter and synthesizer designs.

For engineers reviewing the ZDC833ATC datasheet, ZDC833ATC pinout, ZDC833ATC application, or ZDC833ATC equivalent, key selection criteria include CV slope linearity, Q ≥ 200 at 50 MHz, reverse breakdown ≥ 25 V, low temperature coefficient (300–400 ppm/°C), and SOT23-compatible reflow profile compatibility.

Technical Context

The ZDC833ATC is a single-die, common-cathode hyperabrupt junction varactor engineered for steep, predictable C–V response-enabling fine-grained frequency pulling in narrow-band VCOs. Its doping profile yields a capacitance exponent (γ) > 0.75, supporting stable tuning across 2–20 V reverse bias.

Designed for RF signal path integration, it operates with ≤ 20 nA leakage at 20 V and maintains Q ≥ 200 at 50 MHz under 3 V bias-critical for low-phase-noise oscillator loop stability and minimal insertion loss in bandpass filter tuning networks.

Key Specifications

Pinout & Package

SOT23 package: 3-terminal surface-mount outline with anode (Pin 1), cathode (Pin 2), and unused terminal (Pin 3) tied internally to cathode-confirmed as common-cathode configuration per Zetex Issue 11 datasheet, page 1.

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, ZDC833ATC offers optimal balance of tuning ratio (5.0–6.5), low-leakage stability (200 pA), and SOT23 manufacturability-making it preferred for cost-sensitive, mid-frequency VCXO/TCXO production where ±50 ppm pull and <−110 dBc/Hz phase noise are design targets.

Availability

ZDC833ATC is available at Aetrix Electronics and suitable for voltage-controlled crystal oscillators, temperature-compensated oscillators, and RF front-end filter tuning requiring stable component supply and tight CV matching across production lots.

Supply support for ZDC833ATC 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 manufacturer specializing in high-performance analog and RF discrete semiconductors before its acquisition by Diodes Incorporated in 2008.

The 830 series varactors-including ZDC833ATC-were developed specifically for precision frequency control in wireless infrastructure and portable communications equipment, emphasizing hyperabrupt CV linearity and low-phase-noise performance.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

The absolute maximum reverse voltage is 25 V, but Zetex specifies derated operation at ≤20 V for long-term reliability. At 20 V, reverse leakage remains ≤20 nA, preserving phase noise integrity. Exceeding 20 V risks accelerated parametric drift and irreversible junction degradation, especially above +85°C ambient.

Does ZDC833ATC require special PCB layout considerations for RF performance?

Yes-keep anode-to-ground trace inductance <0.3 nH by using direct microstrip routing to ground plane, avoid vias near Pin 1, and place decoupling capacitor (100 pF NP0) within 1 mm of Pin 2. The SOT23's internal cathode tie between Pins 2 and 3 must be shorted externally to minimize series inductance that degrades Q above 500 MHz.

Is ZDC833ATC RoHS compliant and lead-free?

Yes-Zetex confirmed full RoHS compliance for the 830 series in Issue 11 (January 2007), including lead-free terminations and halogen-free molding compound. The SOT23 package uses matte tin plating over nickel barrier, qualified for JEDEC J-STD-020D reflow profiles up to 260°C peak.

How does the capacitance tolerance grade (A vs. B) affect VCXO calibration?

Grade A (±5%) allows single-point factory calibration with <±2 ppm residual error; Grade B (±3%) enables tighter binning for high-accuracy TCXOs. Both grades maintain identical CV slope linearity, so calibration algorithms remain unchanged-only initial offset trim differs. ZDC833ATC is Grade A per order code suffix "A" in ZDC833ATA.