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Diodes Incorporated ZC933TA
- Part No.:
- ZC933TA
- Manufacturer:
- Diodes Incorporated
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
ZC933TA.pdf
- Description:
- DIODE VAR CAP 42PF 1A SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,314
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Product details
Overview
ZC933TA from Zetex Semiconductors is a 12 V hyperabrupt silicon varactor diode in SOT23 package, designed for voltage-controlled frequency tuning in oscillator circuits. It delivers 42.0 pF capacitance at 1 V, 27.0 pF at 4 V, and minimum Q of 150 at 50 MHz, with reverse leakage ≤100 nA at 8 V - enabling low-phase-noise VCXO/TCXO designs for wireless infrastructure.
For engineers reviewing the ZC933TA datasheet, ZC933TA pinout, ZC933TA application, or ZC933TA equivalent, key selection criteria include its octave-tuning range (0–6 V), hyperabrupt C-V profile, low IR for phase noise sensitivity, SOT23 thermal dissipation (330 mW), and compatibility with miniature RF filter and synthesizer bias networks.
Technical Context
The ZC933TA implements a hyperabrupt junction profile to achieve a steep, linearized C–V response ideal for wide-range frequency pulling in crystal oscillator tanks. Its capacitance varies from 42.0 pF (1 V) to 12.0 pF (4 V), supporting octave tuning across 0–6 V control voltage.
Designed for RF signal path integration, it operates with ≤100 nA reverse leakage at 8 V and exhibits a temperature coefficient of capacitance of +300 to +400 ppm/°C at 3 V and 1 MHz - critical for stability in temperature-varying TCXO environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Capacitance @ 1 V | 42.0 pF - sets low-frequency end of tuning range in VCO tank circuits |
| Capacitance @ 4 V | 12.0 pF - defines high-frequency limit and tuning ratio (3.5:1) |
| Min. Q @ 50 MHz | 150 - limits insertion loss and phase noise degradation in resonant loops |
| Reverse Leakage @ 8 V | ≤100 nA - ensures minimal bias current error and thermal drift in precision oscillators |
| Max. Reverse Voltage | 12 V - establishes safe tuning voltage headroom for ±5 V control rails |
| Package | SOT23 - enables high-density RF layout with 330 mW power dissipation at 25°C |
| Temp. Coeff. of C | +300 to +400 ppm/°C - quantifies frequency drift per °C in uncompensated TCXO topologies |
Pinout & Package
SOT23 package: 3-terminal surface-mount device with anode, cathode, and case (cathode-connected tab). Standard JEDEC MO-203AA outline; 1.77 mm × 2.71 mm footprint; 1.16 mm height; thermally enhanced plastic body rated for 330 mW at 25°C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Control voltage input node | Bias terminal for reverse-biased operation; connects to tuning voltage source via series resistor |
| Cathode (Pin 2) | RF ground reference | Common connection point for crystal/resonator ground and RF return path in Colpitts/Vackar oscillators |
| Case / Tab (Pin 3) | Thermal & electrical ground | Internally tied to cathode; provides thermal conduction path and low-inductance RF grounding when soldered to PCB pour |
Key Features
| Feature | Design Value |
|---|---|
| Hyperabrupt junction profile | Enables linearized frequency vs. voltage response over 0–6 V, reducing calibration complexity in VCXOs |
| Octave tuning range | Supports full doubling of resonant frequency (e.g., 10–20 MHz) using single varactor in crystal load network |
| Low IR (≤100 nA @ 8 V) | Minimizes DC bias shift in high-impedance tuning networks, preserving long-term oscillator center frequency stability |
| High Q ≥150 @ 50 MHz | Reduces resonator losses in 10–100 MHz TCXO tanks, directly improving close-in phase noise (1 kHz offset) |
| SOT23 thermal rating | 330 mW dissipation allows sustained operation under RF drive conditions without derating in compact RF modules |
Applications
| VCXO Frequency Tuning | TCXO Temperature Compensation |
|---|---|
Use Scenario: Voltage-controlled crystal oscillator used in base station reference clock generation requiring ±50 ppm pullability. IC Role / Device Role / Timing Role: Varactor diode placed in series with crystal in Pierce configuration to modulate effective load capacitance. Use Value: 42.0 → 12.0 pF tuning range enables precise 100 ppm total adjustment window with monotonic response and low hysteresis. | Use Scenario: Temperature-compensated crystal oscillator in GPS receiver front-end where ambient drift must be corrected over –40°C to +85°C. IC Role / Device Role / Timing Role: Bias-controlled varactor integrated into analog compensation network that counteracts crystal C vs. T slope. Use Value: +300–400 ppm/°C tempco aligns with typical AT-cut crystal drift, allowing passive analog correction without digital DAC. |
| Wireless Transceiver VCO | Pager IF Filter Tuning |
Use Scenario: Wideband VCO in 800–960 MHz LTE transceiver local oscillator chain requiring fast analog frequency agility. IC Role / Device Role / Timing Role: Hyperabrupt varactor in LC tank to extend tuning bandwidth while maintaining phase noise < –110 dBc/Hz @ 100 kHz. Use Value: Q ≥150 at 50 MHz extrapolates to >80 at 900 MHz, ensuring tank efficiency and spurious suppression in multi-GHz synthesis. | Use Scenario: Tunable bandpass filter in legacy pager receiver IF stage (45 MHz) needing manual or potentiometer-based alignment. IC Role / Device Role / Timing Role: Dual-common-cathode varactor pair (ZC933TA used singly) adjusting center frequency of ceramic resonator ladder filter. Use Value: Low 200 pA typical IR prevents DC offset accumulation in high-Z filter bias nodes, preserving passband symmetry and group delay flatness. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar varactor diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMV1232-011 | Capacitance: 45.0 pF @ 1 V; Q = 200 @ 50 MHz; SOD-323 package; max VR = 15 V | Higher Q and voltage rating support wider tuning range in high-stability OCXO references | Prefer for >100 ppm pullability or >10 V bias rails; requires SOD-323 layout adaptation |
| BBY52-02W | Capacitance: 38.0 pF @ 1 V; Q = 120 @ 50 MHz; SOT-23 package; max VR = 10 V | Lower Q and narrower C range suit cost-sensitive consumer-grade VCOs with relaxed phase noise specs | Select for BOM consolidation where 10 V max VR suffices and 150+ Q not required |
Compared with SMV1232-011 and BBY52-02W, ZC933TA offers balanced octave tuning (42→12 pF), proven low-IR performance for phase noise-critical VCXOs, and direct SOT23 drop-in compatibility - making it optimal for industrial TCXOs where thermal stability and layout reuse outweigh marginal Q gains.
Availability
ZC933TA is available at Aetrix Electronics and suitable for VCXO design, TCXO stabilization, wireless transceiver VCOs, and pager IF filtering requiring stable component supply across extended production lifecycles.
Supply support for ZC933TA 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 (now part of Diodes Incorporated) was a UK-based designer of high-performance analog and RF semiconductors, specializing in discrete devices for precision timing and signal conditioning.
ZC933TA belongs to the ZC93x series of hyperabrupt varactors engineered specifically for low-phase-noise voltage-controlled oscillators and temperature-compensated crystal oscillator modules in telecom and portable radio systems.
FAQ
What is the maximum recommended reverse voltage for continuous operation?
The absolute maximum reverse voltage is 12 V, but for reliable long-term operation in VCXO applications, Zetex specifies 8 V as the maximum operating reverse voltage to maintain ≤100 nA leakage and avoid junction degradation. Derating to 6 V is advised for high-reliability telecom modules operating above 70°C ambient.
How does the hyperabrupt junction improve tuning linearity compared to abrupt varactors?
The hyperabrupt doping profile produces a capacitance change proportional to V−γ where γ ≈ 2–3, yielding near-linear frequency vs. voltage response in crystal oscillator tanks. This reduces second-harmonic distortion and simplifies PLL loop filter design versus abrupt diodes (γ ≈ 0.5) which require complex pre-distortion networks.
Can ZC933TA be used in dual-common-cathode configurations?
No - ZC933TA is a single-diode SOT23 device. Dual-common-cathode variants (e.g., ZC933ATA) exist in the same series but use different marking (A17) and internal construction. Using two ZC933TA units in parallel requires independent biasing and introduces mismatch risk; only ZC933ATA is qualified for matched dual operation.
Is the SOT23 package lead-free and RoHS-compliant?
Yes - per Zetex Issue 7 datasheet (September 2004), ZC933TA conforms to EU RoHS Directive 2002/95/EC. The SOT23 package uses matte tin-plated leads with no lead content, and the molding compound is halogen-free. Full compliance documentation is available under Diodes Incorporated's legacy Zetex product records.
ZC933TA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Capacitance @ Vr, F:
- 12pF @ 4V, 50MHz
- Capacitance Ratio:
- -
- Capacitance Ratio Condition:
- -
- Voltage - Peak Reverse (Max):
- 12 V
- Diode Type:
- Single
- Q @ Vr, F:
- 150 @ 4V, 50MHz
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
ZC933TA FAQ
1.How can I place an order for ZC933TA through Aetrix?
Please submit a Request for Quotation (RFQ) for ZC933TA on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ZC933TA reliable?
The price and inventory of ZC933TA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZC933TA is usually 5 days.
3.What payment methods are accepted for ZC933TA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZC933TA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZC933TA?
ZC933TA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZC933TA order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ZC933TA?
For technical support, including ZC933TA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZC933TA requirements.
6.How does Aetrix verify that ZC933TA is sourced from the original manufacturer or authorized distributors?
All ZC933TA products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ZC933TA meets industry standards.
7.What is the process for return or replacement of ZC933TA?
All ZC933TA units undergo pre-shipment inspection (PSI). If there is an issue with ZC933TA, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ZC933TA part is unused and in its original packaging.
Return procedure for ZC933TA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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