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Diodes Incorporated ZMDC831BTA
- Part No.:
- ZMDC831BTA
- Manufacturer:
- Diodes Incorporated
- Package:
- SC-70, SOT-323
- Datasheet:
-
ZMDC831BTA.pdf
- Description:
- DIODE VARACTOR 25V 15PF SC70-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,398
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Product details
Overview
ZMDC831BTA from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators. It delivers 14.25–15.75 pF capacitance at 2 V, 4.5–6.0 capacitance ratio (C₂/C₂₀), ≥300 Q at 50 MHz, ≤200 pA reverse leakage, and −55 °C to +150 °C operation - deployed in TCXO modules for cellular base station reference clocks.
For engineers reviewing the ZMDC831BTA datasheet, ZMDC831BTA pinout, ZMDC831BTA application, or ZMDC831BTA equivalent, key selection criteria include CV slope linearity, phase-noise contribution in VCO loops, package thermal resistance in SOT23, and compatibility with 0–20 V tuning voltage rails in RF front-end synthesizers.
Technical Context
ZMDC831BTA uses a hyperabrupt junction profile to achieve steep, linearized C–V response across 0–20 V, enabling high-resolution frequency pulling in VCXO/TCXO circuits. Its 300–400 ppm/°C temperature coefficient of capacitance is compensated in oven-controlled designs.
The device operates as a voltage-variable capacitor with no forward conduction required; reverse bias only is applied. Its low IR (≤200 pA) minimizes DC path distortion and preserves oscillator loop Q, directly supporting sub-0.1 dBc/Hz phase noise at 10 kHz offset in 100 MHz fundamental-mode oscillators.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Capacitance @ 2 V | 14.25–15.75 pF - sets center frequency and tuning range in 100–200 MHz VCO tanks |
| Capacitance Ratio C₂/C₂₀ | 4.5–6.0 - enables ±50 ppm frequency pull in TCXO compensation loops |
| Q Factor @ 50 MHz | ≥300 - maintains oscillator phase noise below −150 dBc/Hz at 100 kHz offset |
| Reverse Leakage @ 20 V | ≤20 nA - prevents tuning voltage drift and long-term frequency drift in battery-powered radios |
| Tempco of C @ 3 V | 300–400 ppm/°C - requires matching NPO/COG capacitor or digital compensation in TCXO firmware |
| Max Reverse Voltage | 25 V - supports full-range tuning in 15 V rail VCXOs without breakdown risk |
| Package | SOT23 - provides 0.95 mm lead pitch, 2.1–2.5 mm body length, and 330 mW power dissipation |
Pinout & Package
ZMDC831BTA is housed in an industry-standard SOT23 package (JEDEC TO-236AB), with cathode-marked terminal configuration and 330 mW power rating at 25 °C ambient.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | AC ground / RF return | Connected to ground plane in VCO tank; low-inductance path critical for Q preservation |
| Cathode (Pin 2) | Tuning voltage input | Bias node for 0–20 V control; must be filtered with ≥100 nF ceramic to suppress supply noise |
| Case / Pin 3 | Thermal & electrical ground | Internally tied to cathode in dual-common-cathode variants; used for mechanical mounting and heat sinking |
Key Features
| Feature | Design Value |
|---|---|
| Hyperabrupt junction profile | Delivers linearized Δf/ΔV slope over 0–20 V, reducing calibration complexity in digital TCXOs |
| Low IR (200 pA typ.) | Eliminates need for active leakage compensation circuitry in ultra-low-power pagers |
| High Q (≥300 @ 50 MHz) | Enables use in fundamental-mode 150 MHz oscillators without harmonic filtering overhead |
| Closely controlled CV tolerance | ±3% capacitance binning (B-grade) allows direct replacement without re-tuning VCO PCBs |
Applications
| VCXO Reference Tuning | TCXO Temperature Compensation |
|---|---|
Use Scenario: Voltage-controlled crystal oscillator in LTE small-cell baseband timing module. IC Role / Device Role / Timing Role: Varactor element in Pierce oscillator tank, adjusting crystal load capacitance to correct for aging and supply variation. Use Value: Enables ±2.5 ppm frequency stability over −30 °C to +70 °C using analog tuning voltage from DAC. | Use Scenario: Temperature-compensated crystal oscillator in GPS receiver front-end. IC Role / Device Role / Timing Role: Capacitance modulation element in analog compensation network, counteracting crystal tempco via thermistor-derived bias. Use Value: Achieves <±0.5 ppm total stability over −40 °C to +85 °C without digital calibration. |
| Wireless Transceiver VCO | Pager Frequency Synthesis |
Use Scenario: Wideband VCO in 800 MHz–2.4 GHz software-defined radio transceiver. IC Role / Device Role / Timing Role: Primary tuning diode in Colpitts tank, providing 120 MHz bandwidth with monotonic C–V slope. Use Value: Supports fast hopping (<10 μs settling) while maintaining EVM <2.5% at 64-QAM. | Use Scenario: Low-power FM pager receiver with integrated synthesizer. IC Role / Device Role / Timing Role: Bias-controlled varactor in local oscillator LC tank, tuned by microcontroller DAC output. Use Value: Enables 10-year battery life via 200 pA leakage and 1.8 V compatible tuning range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar varactor diode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMV2023-011LF | Higher C₂/C₂₀ (7.0), lower Q (200 @ 50 MHz), SOD-323 package | Better tuning ratio but higher phase noise; suited for cost-sensitive consumer radios | Select when wider pull range outweighs Q penalty in non-phase-critical receivers |
| BBY52-02W | Lower capacitance (8.2 pF @ 2 V), tighter tempco (±100 ppm/°C), SOT-23 | Narrower tuning range but superior thermal stability; used in aerospace TCXOs | Select when absolute temperature stability > tuning range in high-reliability timing systems |
Compared with SMV2023-011LF and BBY52-02W, ZMDC831BTA offers balanced trade-off: sufficient C₂/C₂₀ for telecom-grade TCXO pull range, high Q for low-phase-noise VCOs, and SOT23 compatibility with existing RF layout footprints.
Availability
ZMDC831BTA is available at Aetrix Electronics and suitable for VCXO reference tuning, TCXO temperature compensation, and wireless transceiver VCO applications requiring stable component supply across production lifecycles.
Supply support for ZMDC831BTA 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 discrete semiconductors before its acquisition by Diodes Incorporated in 2008.
ZMDC831BTA belongs to the 830-series hyperabrupt varactor family, engineered specifically for low-phase-noise frequency control in wireless infrastructure and precision timing equipment.
FAQ
What is the maximum recommended reverse voltage for continuous operation?
The absolute maximum reverse voltage is 25 V per the datasheet, but for reliable long-term operation in TCXO circuits, Zetex specifies 20 V as the maximum continuous tuning voltage. Exceeding this risks accelerated junction degradation and capacitance drift over time, especially above 85 °C ambient.
Does ZMDC831BTA require series current limiting in bias networks?
No - ZMDC831BTA operates exclusively under reverse bias and draws only leakage current (≤200 pA). Series resistors are unnecessary for current limiting but are commonly used (e.g., 100 kΩ) to isolate tuning voltage noise from the oscillator tank without affecting DC bias.
How does the SOT23 package affect thermal performance in high-Q oscillator designs?
The SOT23 package has a junction-to-ambient thermal resistance of ~250 °C/W. In high-Q VCOs where self-heating alters capacitance, board-level copper pour under Pin 3 and short thermal vias reduce θJA to ~120 °C/W, limiting ΔC drift to <0.1% over 50 °C rise.
Is ZMDC831BTA 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 meets JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) for unlimited floor life.
ZMDC831BTA Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- SC-70, SOT-323
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Capacitance @ Vr, F:
- 15.75pF @ 2V, 1MHz
- Capacitance Ratio:
- 6.0
- Capacitance Ratio Condition:
- C2/C20
- Voltage - Peak Reverse (Max):
- 25 V
- Diode Type:
- 1 Pair Common Cathode
- Q @ Vr, F:
- 300 @ 3V, 50MHz
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-323
ZMDC831BTA FAQ
1.How can I place an order for ZMDC831BTA through Aetrix?
Please submit a Request for Quotation (RFQ) for ZMDC831BTA 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 ZMDC831BTA reliable?
The price and inventory of ZMDC831BTA are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZMDC831BTA is usually 5 days.
3.What payment methods are accepted for ZMDC831BTA?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZMDC831BTA transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZMDC831BTA?
ZMDC831BTA orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZMDC831BTA 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 ZMDC831BTA?
For technical support, including ZMDC831BTA datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZMDC831BTA requirements.
6.How does Aetrix verify that ZMDC831BTA is sourced from the original manufacturer or authorized distributors?
All ZMDC831BTA 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 ZMDC831BTA meets industry standards.
7.What is the process for return or replacement of ZMDC831BTA?
All ZMDC831BTA units undergo pre-shipment inspection (PSI). If there is an issue with ZMDC831BTA, 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 ZMDC831BTA part is unused and in its original packaging.
Return procedure for ZMDC831BTA:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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