NXP Semiconductors BAP64Q,125

Overview

BAP64Q,125 from NXP Semiconductors is a quad PIN diode attenuator in SOT753 (SC-74A) package, designed for voltage-controlled RF attenuation across 300 kHz–4 GHz. It integrates four matched PIN diodes with low forward resistance (0.7 Ω typ. at 100 mA), low capacitance (0.23 pF typ. at 20 V reverse), and high linearity (IP3i = 39 dBm at 1 GHz), enabling broadband Π-attenuator circuits in wireless infrastructure and test equipment.

For engineers reviewing the BAP64Q,125 datasheet, BAP64Q,125 pinout, BAP64Q,125 application, or BAP64Q,125 equivalent, key selection criteria include insertion loss (1.8 dB at 1 GHz), attenuation range (38 dB at 1 GHz), thermal resistance (350 K/W), and bias configuration compatibility with shunt-series control topologies.

Technical Context

The BAP64Q,125 implements a monolithic quad-PIN structure optimized for Π-type attenuator networks, where Pins 1 and 3 serve as RF input/output paths while Pins 2, 4, and 5 provide series and dual-shunt bias control. Its intrinsic-layer design enables fast carrier lifetime (1.55 μs) and stable RF performance across temperature (−65 °C to +150 °C junction).

Operation requires external biasing: Pin 2 supplies series diode current, Pins 4 and 5 independently control two shunt branches, enabling precise attenuation tuning via control voltage (0–10 V). The device operates within 125 mW total power dissipation at solder-point temperature ≤90 °C, with reverse voltage rating up to 100 V per diode.

Key Specifications

Pinout & Package

SOT753 (SC-74A) plastic surface-mounted package with 5 leads; 3.1 mm × 2.7 mm footprint, 1.1 mm max height, and 0.95 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MADP-000907-14020T and BAR63-03W, the BAP64Q,125 delivers integrated quad functionality in one SOT753 package, eliminating external matching and reducing part count-critical for compact 4G/5G radio modules where board space and RF consistency are constrained.

Availability

BAP64Q,125 is available at Aetrix Electronics and suitable for cellular infrastructure, RF test instrumentation, wireless repeaters, and defense radar front-ends requiring stable component supply and consistent RF performance across production batches.

Supply support for BAP64Q,125 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 headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and communication markets.

The BAP64Q,125 belongs to NXP's RF PIN diode portfolio, engineered specifically for high-linearity, wideband voltage-controlled attenuation in wireless infrastructure and test equipment-emphasizing low distortion, thermal stability, and monolithic integration.

FAQ

What is the maximum RF input power the BAP64Q,125 can handle continuously?

The BAP64Q,125 has a total power dissipation limit of 125 mW at solder-point temperature ≤90 °C. Its RF power handling depends on bias conditions and frequency, but under typical 100 mA forward bias and 20 V reverse bias, it supports up to +30 dBm (1 W) average RF input in well-heat-sinked layouts. Derating is required above 85 °C ambient per the 350 K/W thermal resistance specification. Always verify thermal performance in the final PCB layout for BAP64Q,125.

Can the BAP64Q,125 be used in a T-attenuator configuration?

No-the BAP64Q,125 pinout and internal diode arrangement are optimized exclusively for Π-attenuator topologies, with dedicated series (Pin 2) and dual-shunt (Pins 4 and 5) bias terminals. A T-configuration would require three series diodes and two shunt paths, which the BAP64Q,125 does not support. For T-attenuators, discrete PIN diodes like the BAP64-03W or MACOM MADP-000907-14020T must be used. The BAP64Q,125 is designed for Π-only implementation.

What is the recommended PCB pad layout for the SOT753 package of the BAP64Q,125?

Follow NXP's SOT753 footprint guidelines: 0.95 mm lead pitch, 0.25 mm lead width, 3.1 mm × 2.7 mm body outline, with thermal pad dimensions matching the 1.7 mm × 1.3 mm exposed copper area shown in Figure 12. Use solder mask defined pads, 0.1 mm solder mask opening oversize, and at least two 0.3 mm thermal vias under the exposed pad connected to inner ground planes. Avoid excessive copper pour near RF pins 1 and 3 to minimize parasitic capacitance in BAP64Q,125 layouts.

Does the BAP64Q,125 require DC blocking capacitors in its RF path?

Yes-DC blocking capacitors are mandatory at RF input (Pin 1) and RF output (Pin 3) to isolate bias voltages from the RF signal path. Typical values are 10 nF ceramic chips (as shown in Figure 3), selected for low ESL and ≥100 V rating to withstand reverse breakdown margins. Without blocking, bias leakage degrades return loss and may forward-bias shunt diodes unintentionally. This requirement applies universally across all operating conditions for BAP64Q,125.

How does temperature affect attenuation accuracy in the BAP64Q,125?

Attenuation varies with temperature due to diode parameter drift: Figures 7–10 show ±1.5 dB deviation over −40 °C to +80 °C at fixed control voltage and frequency. At 1 GHz and Vctrl = 10 V, attenuation shifts from 38.2 dB at 25 °C to 36.7 dB at 80 °C. For precision applications, closed-loop calibration or temperature-compensated biasing is recommended. The BAP64Q,125 datasheet provides full curves to model this behavior in system-level simulations.