NXP Semiconductors BAP1321-03,115

Overview

BAP1321-03 from NXP Semiconductors is a silicon PIN diode in SOD323 (SC-76) package, designed as an RF resistor for high-frequency attenuators and switches up to 3 GHz. It delivers low diode capacitance (0.25–0.45 pF at 1 MHz), low forward resistance (0.85–5.0 Ω depending on bias), and very low series inductance (1.5 nH), enabling precise RF signal control in compact wireless front-ends.

For engineers reviewing the BAP1321-03 datasheet, BAP1321-03 pinout, BAP1321-03 application, or BAP1321-03 equivalent, key selection criteria include reverse voltage rating (60 V), forward current capability (100 mA), thermal resistance (120 K/W), isolation performance (≥9.2 dB at 2.45 GHz), and SOD323 package compatibility with high-density RF PCB layouts.

Technical Context

The BAP1321-03 operates as a voltage-controlled RF resistor: its forward resistance decreases with increasing DC bias current (e.g., 1.2 Ω at 10 mA, 0.85 Ω at 100 mA), while reverse-biased capacitance drops from 0.4 pF at 0 V to 0.25 pF at 20 V. This enables tunable attenuation and switching in 50 Ω stripline circuits.

Its charge carrier lifetime (0.5 μs) and ultra-low series inductance (1.5 nH) support fast switching and minimal parasitic phase shift up to 2.45 GHz. Performance is characterized at T_j = 25 °C with guaranteed specs on AQL basis (S4, AQL 1.0).

Key Specifications

Pinout & Package

Package: SOD323 (SC-76), ultra-small surface-mount plastic package with 2 leads; marking bar indicates cathode; outline conforms to IEC/JEDEC/JEITA standards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RF PIN diode applications.

Compared with BAP1321-03, the MADP-000907-14150W offers extended frequency range and power headroom but requires PCB redesign, while the BAR63-03W retains SOD323 compatibility at the expense of reverse voltage margin and high-frequency isolation.

Availability

BAP1321-03 is available at Aetrix Electronics and suitable for cellular front-end switching, Wi-Fi 2.4 GHz attenuation, and ISM band receiver protection requiring stable component supply and consistent RF performance across production batches.

Supply support for BAP1321-03 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

NXP Semiconductors is a global semiconductor company delivering high-performance mixed-signal and standard products, with leadership in RF, analog, and interface technologies.

The BAP1321-03 belongs to NXP's discrete RF PIN diode product line, engineered specifically for high-isolation, low-loss switching and attenuation in compact wireless infrastructure and mobile handset applications up to 3 GHz.

FAQ

What is the maximum reverse voltage rating for the BAP1321-03?

The BAP1321-03 has a continuous reverse voltage rating of 60 V, as specified in the Absolute Maximum Ratings table. This value defines the highest DC or peak RF voltage the diode can withstand in reverse bias without breakdown. Exceeding this limit risks permanent damage. The BAP1321-03 maintains stable capacitance and leakage performance up to this rating, making it suitable for high-isolation RF switch designs in cellular and ISM band systems.

How does forward current affect the RF resistance of the BAP1321-03?

The BAP1321-03 exhibits a strong inverse relationship between forward current and RF forward resistance: at 0.5 mA bias, r_D is 3.4–5.0 Ω; at 100 mA, it drops to 0.85–1.3 Ω (measured at 100 MHz). This behavior enables precise, current-tuned attenuation in RF paths. The BAP1321-03 datasheet provides tabulated r_D values across four bias points, allowing designers to select optimal operating current for target insertion loss and power handling.

What is the typical diode capacitance of the BAP1321-03 at 20 V reverse bias?

At 20 V reverse bias and 1 MHz, the BAP1321-03 has a typical diode capacitance of 0.25 pF, with a maximum of 0.32 pF. This low capacitance minimizes shunt loading on RF traces and preserves matching network integrity in high-frequency applications such as 2.45 GHz Wi-Fi front-ends. The BAP1321-03 datasheet confirms this value in the Characteristics section and illustrates its voltage dependence in Figure 3.

Can the BAP1321-03 be used in 5 GHz applications?

No, the BAP1321-03 is characterized and specified for operation up to 3 GHz, with isolation and insertion loss data provided only through 2.45 GHz. At 5 GHz, parasitic effects-particularly series inductance (1.5 nH) and package resonance-degrade performance beyond datasheet guarantees. For 5 GHz use, consider alternatives like the MADP-000907-14150W, which is rated to 6 GHz. The BAP1321-03 should not be deployed outside its validated frequency envelope.

What does the marking code 'V8' indicate on the BAP1321-03 package?

'V8' is the manufacturer's top-side marking code for the BAP1321-03, uniquely identifying this specific PIN diode variant within NXP's SOD323 portfolio. The bar adjacent to the marking denotes Pin 1 (cathode), confirming polarity for correct PCB placement. This marking aligns with NXP's standard coding scheme and is verified in the Package Outline drawing (page 5 of the datasheet). The BAP1321-03 must be oriented with the bar toward the cathode net in the schematic to ensure proper RF and DC functionality.