BAP70 - 50V Silicon PIN Diode SOD-523 | NXP | RF Attenuator
MPN: BAP70 β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0 | $0.00 |
| 10 | $0 | $0.00 |
| 100 | $0 | $0.00 |
| 500 | $0 | $0.00 |
| 1,000 | $0 | $0.00 |
BAP70 Overview
A PIN diode is a type of diode with a wide, lightly doped intrinsic semiconductor region sandwiched between p-type and n-type regions. At RF and microwave frequencies, this intrinsic layer makes the diode behave as a current-controlled resistor, which is why PIN diodes form the core of RF attenuators, RF switches, and AGC (automatic gain control) circuits. Within the signal-chain hierarchy, the BAP70 belongs to the discrete semiconductor family: PIN diode -> RF diode -> diode -> discrete component.
Key features of the BAP70 family include high reverse voltage capability (50 V), very low diode capacitance at reverse bias, and very low series inductance thanks to the compact SOD-523 package geometry. These attributes minimize parasitic effects in the RF path, preserving insertion-loss performance at VHF, UHF, and microwave frequencies. The BAP70-02 variant is qualified to the AEC-Q101 automotive standard, making it suitable for automotive-grade RF designs.
The planar PIN structure provides a well-controlled series resistance versus forward current characteristic, allowing designers to linearly control attenuation by varying DC bias current. Because the RF resistance spans a wide range with modest current, a single device can serve in continuously variable attenuators, switchable attenuator pads, and antenna tuning networks.
Typical applications include RF attenuators in satellite (SAT) television front ends, car radio antenna tuning and AGC circuits, and general RF/microwave gain-control stages where a voltage-controlled resistance is required.
A key design consideration is that the RF series resistance is strongly bias-current dependent; layout must keep the bias network decoupled from the RF path to prevent signal injection into the control line.
This page synthesizes distributor data, drop-in alternatives, and practical design notes not found in the manufacturer datasheet, with pricing and lifecycle freshness as of 2026-09-14.
Drop-in alternatives for BAP70 β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
BAP70-02,115
β Drop-Inπ Reference alternative (not in catalog)
BAP70-02/AX
β Drop-Inπ Reference alternative (not in catalog)
BAP70-02,132
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
BAP64-02,115
β Drop-In β οΈ εζ°εΎ ιͺθ―π Reference alternative (not in catalog)
BAP70 Maximum Ratings & Electrical Characteristics
| Diode Type | Silicon PIN diode (RF) |
| Configuration | Single |
| Reverse Voltage (VR) | 50 V |
| Forward Current (IF) | 100 mA |
| Power Dissipation | 415 mW |
| Application | RF attenuator / current-controlled RF resistor |
| Package | SOD-523 (2-pin SMD plastic) |
| Mounting Type | Surface Mount |
| Automotive Qualification | AEC-Q101 qualified (BAP70-02 variant) |
| Typical Applications | RF attenuators (SAT TV, car radio) |
| Technology | Planar PIN |
| Ordering Code Example | BAP70-02,115 |
BAP70 Pin Configuration
| Pin 1 | Cathode β Cathode terminal of the PIN diode (marking side) |
| Pin 2 | Anode β Anode terminal of the PIN diode |
Typical Applications
BAP70 is suitable for 6 applications: Satellite TV RF Attenuators, Car Radio Antenna Tuning, RF AGC and Gain-Control Stages, RF Switching Circuits, Impedance Matching and Tuning Networks, Test and Measurement Attenuator Pads.
Satellite TV RF Attenuators
In satellite (SAT) television front ends, the incoming L-band signal must be level-controlled to prevent receiver overload. The NXP BAP70-02, rated 50 V reverse voltage and 100 mA forward current, is explicitly listed by NXP as a PIN diode for SAT TV attenuators. Its very low diode capacitance minimizes off-state shunt loading of the 50-ohm path, while its current-controlled series resistance allows smooth, continuous attenuation by adjusting DC bias current. Placed as a series or shunt element with bias fed through an RF choke and bypassed control line, the BAP70 delivers wide-range AGC without switching artifacts. The 415 mW dissipation rating provides ample margin for the modest RF power levels in satellite tuners, and AEC-Q101 qualification extends its use to harsher environments.
Recommended
Car Radio Antenna Tuning
Automotive AM/FM and digital radio receivers use voltage-controlled attenuators and tuning elements in the antenna input path to combat fading and strong-signal overload. The BAP70-02 carries AEC-Q101 automotive qualification, making it appropriate for the demanding temperature and reliability requirements of vehicle electronics. Its 50 V reverse rating gives headroom against transients on the antenna line, and the very low series inductance of the SOD-523 package preserves signal integrity at VHF frequencies. NXP's datasheet specifically names car radio as a target application. The diode's RF resistance is set by a small DC control current from the tuner AGC loop, letting the receiver continuously optimize input level. Designers should decouple the bias node thoroughly to keep RF off the control harness.
Recommended
RF AGC and Gain-Control Stages
Automatic gain control (AGC) stages in RF receivers and IF chains require a variable resistance that behaves identically across a wide frequency span. The BAP70's planar PIN structure provides a monotonic series-resistance versus forward-current characteristic, so the loop gain of an AGC can be engineered directly from the datasheet resistance curves. With only 2 pins and the ultra-small SOD-523 footprint, it fits densely populated attenuator pads between LNA and mixer stages. The very low diode capacitance keeps the off-state insertion loss low, an important property when AGC must attenuate by many decibels without disturbing the passband. Bias currents are in the milliamp range, so control power is minimal, and the 50 V rating protects against large signal swings in wide-dynamic-range receivers.
Recommended
RF Switching Circuits
PIN diodes also function as RF switches: forward bias presents a low resistance (ON) and reverse bias a small capacitance (OFF). The BAP70's very low diode capacitance and very low series inductance yield a high OFF-state impedance and low ON-state insertion loss, key metrics for transmit/receive and antenna switching in consumer and automotive radios. The 50 V reverse voltage rating allows switching of relatively high RF peak voltages, and the 100 mA / 415 mW ratings cover the DC bias plus RF dissipation in typical small-signal switches. Switching speed is set by carrier lifetime in the intrinsic region, so series and shunt configurations should include appropriate bias resistors and DC-block capacitors per standard PIN switch topologies described in the NXP datasheet.
Recommended
Impedance Matching and Tuning Networks
Electronically tunable matching networks, used in antenna tuners and multi-band RF front ends, exploit the bias-dependent reactance/resistance of PIN diodes to trim network impedance without mechanical adjustment. The BAP70 combines a 50 V rating with very low capacitance, so a series diode in a tuning stub introduces minimal fixed parasitics while the control current sets the effective resistance or, with bias-dependent charge storage, contributes to the tuning function. The SOD-523 package's low series inductance is especially valuable here because the diode is often placed in high-Q paths where even a fraction of a nanohenry shifts the resonant frequency. Designers should simulate the full bias-dependent diode model and verify tuning range across the AEC-Q101 temperature range for automotive variants.
Recommended
Test and Measurement Attenuator Pads
Bench and production RF test equipment frequently uses switchable and continuously variable attenuator pads built from PIN diodes. The BAP70 is well suited to these pads because its RF resistance is smoothly current-controlled over a wide range, enabling programmable step attenuators with fine resolution when combined with a DAC-driven bias source. The 415 mW dissipation rating accepts the levels typical of signal-generator outputs, and the 50 V rating handles high peak voltages from pulsed sources. Because SOD-523 is a tiny two-terminal package, pads can be laid out with short, symmetrical traces that maintain return-loss performance into the gigahertz range. For calibration, characterize each diode's resistance-versus-current curve at operating temperature, as PIN diode resistance drifts with temperature.
Recommended
Recommended Products Summary
Engineering reference data for BAP70 β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | BAP70-02,115 | BAP70-02/AX | BAP70Q,125 |
|---|---|---|---|---|
| Package | SOD-523 (2-pin) | SOD-523 (2-pin) - same | SOD-523 (2-pin) - same | 5-pin TSOP (pair) - different package |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors (Rochester Electronics) | NXP Semiconductors |
| Diode Configuration | Single PIN diode | Single PIN diode | Single PIN diode | Pair, CA + CC |
| Reverse Voltage | 50 V | 50 V | 50 V | 50 V |
| Forward Current | 100 mA | 100 mA | 100 mA | 100 mA |
| Power Dissipation | 415 mW | 415 mW | 415 mW | 125 mW (pair configuration) |
| AEC-Q101 Automotive | Yes (BAP70-02 variant) | Yes | Yes | Yes (Q suffix) |
| Primary Application | RF attenuator (SAT TV, car radio) | RF attenuator (SAT TV, car radio) | RF attenuator (SAT TV, car radio) | RF attenuator / pair topologies |
| Pin Count | 2 | 2 | 2 | 5 |
Key Differentiators
- Very low series inductance package (vs BAP70Q,125)
- AEC-Q101 automotive qualification (vs Generic unqualified PIN diodes)
- 50 V reverse rating with 100 mA / 415 mW (vs BAP70Q,125)
Design Notes
Mount the BAP70 directly in the 50-ohm RF path with the shortest possible traces. The SOD-523 package achieves very low series inductance, but this benefit is lost if the PCB adds stubs or via transitions in series with the diode. Keep the two pads symmetrical and reference the shunt side to a continuous ground plane directly beneath. Estimated: even 1 nH of extra series inductance adds roughly 0.5 ohm of reactance at 80 MHz and 6 ohm at 1 GHz, visibly shifting attenuator flatness.
Feed the diode bias through an RF choke or a resistor large enough to present high RF impedance, and bypass the control node to ground with a capacitor chosen for the lowest operating frequency. Without this, RF leaks into the control line and the effective attenuation becomes frequency- and load-dependent. Keep bias current within the 100 mA rating and total dissipation below the 415 mW limit, derating at elevated ambient temperature per the datasheet derating curve.
Do not treat the BAP70 as a fixed resistor: its RF series resistance is set by forward bias current and must be read from the datasheet resistance-versus-current curves at the actual operating point. Reverse-bias capacitance is the off-state parameter that governs isolation - do not substitute a diode without comparing both curves. For automotive designs, use only the AEC-Q101-qualified BAP70-02 variant, not unqualified equivalents.
Compliance Information
The BAP70-02 variant is AEC-Q101 (automotive discrete semiconductor) qualified per web data. RoHS/REACH status must be confirmed on the NXP product page for the specific ordering code (,115 suffix typically denotes lead-free/RoHS reeled product).
