Diodes Incorporated ZC834BTC

Overview

ZC834BTC from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators and RF filters. It delivers 47.0 pF nominal capacitance at 2 V, 5.0–6.5 capacitance ratio (C₂/C₂₀), ≥200 Q 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 ZC834BTC datasheet, ZC834BTC pinout, ZC834BTC application, or ZC834BTC equivalent, key selection criteria include its hyperabrupt CV slope for steep tuning response, SOT23 package compatibility with high-density RF layouts, guaranteed C₂/C₂₀ ≥5.0, and verified 25 V reverse breakdown rating-critical for stable VCO gain and temperature-invariant frequency pulling.

Technical Context

The ZC834BTC employs a hyperabrupt junction profile engineered to produce a steep, linearized voltage-to-capacitance transfer function-essential for minimizing tuning nonlinearity and harmonic distortion in voltage-controlled oscillators. Its capacitance varies from 42.3 pF (min) to 51.7 pF (max) at VR = 2 V, f = 1 MHz, with tight process control ensuring ±5% unit-to-unit CV matching across production lots.

Designed for RF signal path integration, it maintains Q ≥200 at 50 MHz under 3 V bias, supporting low-insertion-loss filter tuning and phase noise suppression in 800–2500 MHz bands. The 300–400 ppm/°C temperature coefficient of capacitance is compensated in TCXO reference loops via analog or digital correction algorithms.

Key Specifications

Pinout & Package

Supplied in SOT23 package (JEDEC TO-236AB), with cathode-marked lead configuration. Dimensions: 2.67–3.05 mm × 1.20–1.40 mm × 0.95 mm height; 3-terminal surface-mount outline compatible with standard reflow profiles.

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, ZC834BTC offers optimal balance of mid-range capacitance (47 pF), high tuning ratio (≥5.0), and superior Q (≥200), making it preferred for medium-bandwidth, low-phase-noise VCOs where both range and spectral purity are critical.

Availability

ZC834BTC is available at Aetrix Electronics and suitable for VCXO design, TCXO compensation, and RF filter tuning requiring stable component supply, consistent CV matching, and RoHS-compliant SMT packaging.

Supply support for ZC834BTC 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 and 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 ZC834BTC-were developed specifically for precision frequency control in wireless infrastructure and mobile communications, emphasizing hyperabrupt CV linearity, low leakage, and high-Q RF performance.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

The ZC834BTC has a minimum reverse breakdown voltage of 25 V, and its absolute maximum rating is defined at 25 V. For reliable long-term operation, Zetex recommends limiting reverse bias to ≤20 V to maintain margin against process variation and temperature derating-especially critical in TCXO applications where bias stability directly impacts frequency accuracy.

Does ZC834BTC require special PCB layout considerations for RF performance?

Yes. To preserve Q ≥200 at 50 MHz, the cathode (Pin 2) must connect to a solid RF ground plane with minimal trace inductance (<0.5 nH), and the anode (Pin 1) should route through a low-noise, filtered bias network. Avoid routing other signals near the SOT23 pads, and use ground vias within 1 mm of the cathode pad to suppress resonance modes above 1 GHz.

How does the 300–400 ppm/°C temperature coefficient affect TCXO design?

This tempco defines the raw drift of capacitance versus temperature, which translates directly to oscillator frequency drift. In TCXO implementations, it is measured and compensated using either analog thermistor networks or digital lookup tables. The tight ±5% CV tolerance across lots reduces calibration complexity, allowing single-point compensation in high-volume production.

Is ZC834BTC compatible with lead-free reflow profiles?

Yes. As a RoHS-compliant device in SOT23 package, ZC834BTC is qualified for standard JEDEC J-STD-020D lead-free reflow, with peak temperature up to 260°C for ≤30 seconds. Thermal mass and pad design must follow Zetex's recommended footprint (0.37–0.53 mm lead width, 2.10–2.50 mm body length) to prevent tombstoning or solder voiding.