Diodes Incorporated ZC831BTA

Overview

ZC831BTA from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators and RF filters. It delivers 14.25–15.75 pF capacitance at 2 V, 4.5–6.0 capacitance ratio (C₂/C₂₀), ≥300 Q at 50 MHz, and ultra-low reverse leakage (typ. 200 pA), enabling low-phase-noise VCXO/TCXO designs in wireless infrastructure.

For engineers reviewing the ZC831BTA datasheet, ZC831BTA pinout, ZC831BTA application, or ZC831BTA equivalent, key selection criteria include its hyperabrupt CV slope for steep tuning response, SOT23 package compatibility with high-density RF layouts, and guaranteed 25 V reverse breakdown for robust bias margin in 3–5 V control systems.

Technical Context

ZC831BTA operates as a voltage-variable capacitor whose junction capacitance varies nonlinearly with applied reverse bias-specifically engineered with hyperabrupt doping profile to yield steeper dC/dV than abrupt or linear diodes. Its CV curve is tightly controlled across production lots to ensure predictable oscillator pulling range and filter center-frequency stability.

The device exhibits minimal temperature coefficient of capacitance (300–400 ppm/°C) and maintains Q ≥300 at 50 MHz under 3 V bias, supporting stable resonator performance in temperature-varying environments. Reverse leakage remains below 20 nA up to 20 V, directly contributing to low close-in phase noise in oscillator loop designs.

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). The NC pin provides mechanical stability and thermal relief without electrical function.

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, ZC831BTA offers optimal balance of mid-range capacitance, high Q, and tight CV control-making it preferred for 1–2.5 GHz VCXOs requiring both resolution and phase noise integrity.

Availability

ZC831BTA is available at Aetrix Electronics and suitable for VCXO frequency tuning, RF bandpass filter tuning, and TCXO temperature compensation requiring stable component supply and traceable lot history.

Supply support for ZC831BTA 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.

ZC831BTA belongs to the 830 series hyperabrupt varactor family, engineered specifically for low-phase-noise frequency control in telecom, wireless, and precision timing systems where CV slope and repeatability are critical.

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, ensuring minimal impact on oscillator bias networks and phase noise. Exceeding 20 V risks accelerated parametric drift without immediate failure.

Can ZC831BTA be used in dual-common-cathode configurations?

No-ZC831BTA is a single-diode SOT23 device. Dual variants like ZMV831BTA exist in the same series but use different marking (CC) and internal structure. Substituting ZC831BTA into a dual-cathode layout will result in open-circuit behavior on the second channel and incorrect biasing.

How does the SOT23 package affect thermal performance in high-Q oscillator designs?

The SOT23 package dissipates up to 330 mW at 25°C ambient, but in oscillator tanks, power dissipation is negligible (<100 µW). Thermal resistance (R_θJA) is ~220°C/W, so self-heating is <0.02°C under normal bias-well below the 300 ppm/°C tempco threshold, preserving CV stability.

Is ZC831BTA RoHS compliant and lead-free?

Yes-Zetex confirmed full RoHS compliance for the 830 series per Directive 2011/65/EU. The SOT23 package uses matte tin (Sn) lead finish with no lead, cadmium, mercury, hexavalent chromium, PBB, or PBDE. Lot traceability and CoC documentation are available upon request.