Diodes Incorporated ZC829BTA

Overview

ZC829BTA from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators and RF filters. It delivers 7.79–8.61 pF capacitance at 2 V, 4.3–5.8 capacitance ratio (C₂/C₂₀), Q ≥ 250 at 50 MHz, and reverse leakage ≤ 200 pA - enabling low-phase-noise VCXO/TCXO designs in wireless infrastructure and mobile radio front-ends.

For engineers reviewing the ZC829BTA datasheet, ZC829BTA pinout, ZC829BTA application, or ZC829BTA equivalent, key selection criteria include its hyperabrupt CV slope, SOT23 package compatibility, 25 V reverse breakdown rating, and guaranteed low IR for phase noise–sensitive tuning circuits.

Technical Context

The ZC829BTA employs a hyperabrupt junction profile to achieve steep, linearized C–V response across 2–20 V, critical for stable frequency pulling in voltage-controlled crystal oscillators. Its capacitance tolerance (±0.41 pF at 2 V) and tight C₂/C₂₀ spread (4.3–5.8) ensure predictable tuning gain without calibration.

Designed for RF signal path integration, it maintains Q ≥ 250 at 50 MHz under 3 V bias, minimizing insertion loss in bandpass/VCO tank networks. The 25 V reverse breakdown and −55°C to +150°C operating range support robust operation in temperature-varying wireless transceivers.

Key Specifications

Pinout & Package

Supplied in SOT23 package (JEDEC TO-236AB), with cathode-marked lead configuration. Pin 1 = Anode, Pin 2 = Cathode, Pin 3 = Not connected (NC) - confirmed per Zetex SOT23 outline drawing Issue 11, page 5.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAVR-000120-1411 and SMV1232-011, ZC829BTA offers the optimal balance of Q, C₂/C₂₀, and leakage for telecom-grade VCXOs - delivering lower integrated phase noise than MAVR while providing broader tuning than SMV1232.

Availability

ZC829BTA is available at Aetrix Electronics and suitable for VCXO design, RF filter tuning, and mobile radio transceiver development requiring stable component supply and traceable lot-level compliance.

Supply support for ZC829BTA 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 analog semiconductor manufacturer specializing in high-performance discrete devices before its acquisition by Diodes Incorporated in 2008.

The 830 series varactors were engineered specifically for frequency control in wireless infrastructure and portable communications equipment, emphasizing hyperabrupt CV linearity, low phase noise, and miniature SMT reliability.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

The ZC829BTA has a rated reverse breakdown voltage of 25 V, with absolute maximum reverse voltage specified at 20 V for reliable long-term operation. Operating above 20 V risks irreversible junction damage and increased leakage; design margin should maintain VR ≤ 18 V in production circuits.

Does ZC829BTA require DC blocking in RF signal paths?

No - the device is designed for direct series connection in RF tank circuits. Its anode serves as the DC tuning input, while the cathode connects to AC ground; no external blocking capacitor is needed unless the bias network shares a node with active RF components.

How does temperature affect capacitance stability in ZC829BTA?

Capacitance varies with temperature at 300–400 ppm/°C, measured at 3 V and 1 MHz. This tempco is consistent across the 830 series and is factored into TCXO compensation algorithms; actual drift in a tuned oscillator remains <±0.5 ppm/°C when combined with standard crystal compensation.

Is ZC829BTA 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 compounds. The SOT23 package meets JEDEC J-STD-020 moisture sensitivity level 1 and supports standard Pb-free reflow profiles.