ZMDC953TA

Overview

The ZMDC953TA is a dual silicon hyperabrupt varactor diode from the 950 series, designed for frequency control and filtering applications. It features closely controlled capacitance-voltage characteristics, low reverse leakage current (typically 10pA), and high Q factors at low voltages. The device operates with control voltages ranging from 0.5V to 2.5V, making it suitable for 3V systems. Key electrical parameters include a maximum reverse voltage of 12V, a typical reverse leakage of 20nA at 8V, and a power dissipation of 250mW in SOD523 packaging. Capacitance values are specified as 45pF at 0.5V and 30pF at 1.5V.

Feature Summary

• Dual configuration providing two independent varactor elements in a single miniature surface mount package.
• Hyperabrupt junction design ensures tight tolerance capacitance-voltage characteristics for precise tuning.
• Low reverse leakage current contributes to excellent phase noise performance in oscillator circuits.
• Optimized for operation within 0.5V to 2.5V control voltage ranges.

Applications

• Voltage Controlled Crystal Oscillators (VCXO)
• Temperature Compensated Crystal Oscillators (TCXO)
• Wireless communications systems
• Digital Radio receivers

Procurement Notes

Verify the specific order code against the manufacturer's documentation to ensure correct band selection if tighter capacitance tolerances are required. Confirm that the received reels contain the intended capacitance band, as availability is process-dependent and shipments may contain mixed bands. Ensure handling procedures comply with the moisture sensitivity level indicated in the datasheet.

Selection Notes

Select the ZMDC953TA when a dual varactor solution is needed for balanced tuning or differential circuits. Consider the FSD273TA variant if specific capacitance bands are necessary for strict frequency accuracy. Evaluate the trade-off between the standard 950 series tolerance and the banded version based on the application's phase noise requirements.

Part Context

This component belongs to the 950 series of silicon low voltage hyperabrupt varactor diodes originally developed by Zetex plc and now distributed by Diodes Incorporated. The series includes single variants like the ZV953V2 and the dual ZMDC953. These devices are engineered for compact designs requiring stable capacitance variation over a narrow voltage range.

Replacement Considerations

The FSD273TA is a band-selected version of the ZMDC953 offering tighter capacitance ranges. Single-element equivalents in the same series include the ZV953V2 for non-dual applications.