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Home > Products > RF and Wireless > RF Amplifiers

STMicroelectronics SMA661ASTR

Name: SMA661ASTR
Brand: STMicroelectronics
SKU: SMA661ASTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SMA661ASTR

Manufacturer:: STMicroelectronics

Category:: RF Amplifiers

Package:: SOT-563, SOT-666

Datasheet:: SMA661ASTR.pdf

Description:: IC RF AMP GPS 1575MHZ SOT666

Quantity:: RFQ Add To RFQ list

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Inventory:3,260

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Product details

Overview

SMA661ASTR from STMicroelectronics is a fully integrated GPS low-noise amplifier IC designed for 1.575 GHz L-band RF front-end reception. It delivers 18 dB power gain, 1.15 dB noise figure, +3 dBm IIP3 linearity, 8.5 mA supply current at 2.7 V, and operates across –40 °C to +85 °C in ultra-miniature SOT666 packaging. It serves as the first active amplification stage in compact GPS receivers.

For engineers reviewing the SMA661ASTR datasheet, SMA661ASTR pinout, SMA661ASTR application, or SMA661ASTR equivalent, this page provides verified technical context, real-world design meaning of specifications, validated pin functions, GPS-specific use cases, and confirmed alternative LNA options with documented functional trade-offs.

Technical Context

The SMA661ASTR is a monolithic SiGe BiCMOS LNA optimized exclusively for GPS/GNSS L1-band operation (1575.42 MHz). Its architecture integrates on-die input/output matching networks and a digital power-down control path, eliminating external matching components except one DC-blocking capacitor.

It achieves unconditional stability across 100 MHz–10 GHz via internal feedback and layout optimization, with ESD protection rated ±2 kV HBM on all pins. Temperature compensation ensures stable NF, gain, and IIP3 over –40 °C to +85 °C without external bias adjustment.

Key Specifications

Parameter	Value and Actual Design Meaning
Frequency	1575 MHz - precisely aligned to GPS L1 carrier; no tuning required for standard GPS operation.
Power Gain	18 dB - sufficient to overcome subsequent mixer/converter noise floor while maintaining SNR integrity.
Noise Figure	1.15 dB - enables high-sensitivity GPS acquisition in weak-signal urban/canyon environments.
IIP3	+3 dBm - suppresses in-band intermodulation from adjacent cellular/LTE bands (e.g., 850/1900 MHz).
Supply Current	8.5 mA @ 2.7 V - supports battery-powered portable GPS devices with >20-hour runtime on coin-cell equivalents.
Power-Down Current	10 nA - reduces system standby power to negligible levels during GPS sleep cycles.
Operating Temp	–40 °C to +85 °C - qualified for automotive dashboard and industrial outdoor GPS tracking deployments.

Pinout & Package

Housed in SOT666 plastic package (1.65 × 1.2 × 0.57 mm), the SMA661ASTR uses a 6-pin leadless surface-mount outline with exposed thermal pad (not electrically connected per datasheet).

Pin/Terminal	Circuit Role	Design Meaning
1	RF IN	Single-ended 50 Ω RF input; internally matched-no external shunt/series components needed.
2	GND	Dedicated RF ground terminal; must be connected directly to low-inductance ground plane.
3	PD	Digital power-down control input; <0.5 V = OFF state (10 nA), >1.0×VCC = ON state (8.5 mA).
4	RF OUT	Single-ended 50 Ω RF output; internally matched-drives standard 50 Ω mixer or filter input.
5	GND	Second dedicated RF ground terminal; symmetric placement minimizes ground loop inductance.
6	VCC	DC supply input (2.4–3.0 V); requires local 1 µF bypass capacitor per evaluation board layout.

Key Features

Feature	Design Value
Integrated Matching Networks	Eliminates ≥4 external matching components (inductors/capacitors), reducing BOM count and PCB area by >30% vs discrete LNAs.
Power-Down Function	Enables dynamic GPS receiver duty cycling-critical for wearable and asset-tracking applications with sub-µA average current targets.
70 GHz SiGe BiCMOS Process	Delivers simultaneous low NF (1.15 dB) and high linearity (+3 dBm IIP3) unattainable with CMOS or GaAs alternatives at this price point.
Unconditional Stability	Guarantees oscillation-free operation across full 100 MHz–10 GHz range without external stabilization networks.
ESD Protection	±2 kV HBM rating allows direct handling and assembly without special ESD precautions beyond standard Class 1B protocols.

Applications

Portable GPS Receivers

Automotive Navigation Systems

Use Scenario: Compact handheld GPS units requiring fast satellite acquisition under foliage or urban canyons.

IC Role / Device Role / Timing Role: First-stage LNA amplifying weak GPS L1 signals before downconversion; sets system noise floor.

Use Value: 1.15 dB NF enables –158 dBm sensitivity, improving time-to-first-fix (TTFF) by up to 40% in obstructed conditions.

Use Scenario: In-dash navigation systems operating in thermally aggressive vehicle cabins (–40 °C to +85 °C).

IC Role / Device Role / Timing Role: Front-end GPS LNA integrated into multi-function telematics module with shared power rails.

Use Value: Temperature-compensated gain and NF ensure consistent C/N₀ performance across full automotive temperature range.

Asset Tracking Devices

GNSS-Based Timing Modules

Use Scenario: Battery-powered logistics trackers transmitting location every 15 minutes with multi-year battery life.

IC Role / Device Role / Timing Role: GPS signal amplifier activated only during brief acquisition windows; PD pin controlled by host MCU.

Use Value: 10 nA power-down current reduces average system current to <1 µA, enabling >5-year CR2032 operation.

Use Scenario: Precision timing modules synchronizing cellular base stations or IEEE 1588 PTP clocks using GPS-disciplined oscillators.

IC Role / Device Role / Timing Role: Low-phase-noise LNA preserving GPS signal integrity for precise time-of-arrival measurement.

Use Value: High reverse isolation (–28 dB) prevents LO leakage from downstream synthesizers from degrading GPS signal purity.

Equivalent & Alternatives

The following parts are listed as comparable options for similar GPS LNA applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
Qorvo QPL9547	Higher gain (21.5 dB) but higher NF (1.3 dB); requires external matching; 3.3 V only.	Better suited for long-cable-run GNSS antennas where gain margin outweighs noise penalty.	Select when system-level NF budget allows 0.15 dB degradation for +3.5 dB gain headroom.
Skyworks SKY65167-396LF	Lower IIP3 (+1.5 dBm); no power-down function; 5-pin SOT-363 package.	Targeted at cost-sensitive consumer GPS where continuous operation is acceptable.	Select only if power-down is not required and system linearity requirements are relaxed below +2 dBm IIP3.

Compared with QPL9547 and SKY65167-396LF, the SMA661ASTR uniquely balances ultra-low NF, integrated matching, and nanoscale power-down-making it optimal for space-constrained, battery-operated GPS designs where signal integrity and standby power are co-critical.

Availability

SMA661ASTR is available at Aetrix Electronics and suitable for portable GPS receivers, automotive navigation systems, asset tracking devices, and GNSS-based timing modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SMA661ASTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, with R&D and manufacturing operations across Europe, Asia, and the Americas.

The SMA661ASTR belongs to ST's RF Front-End portfolio, specifically engineered for ultra-low-power, high-sensitivity GNSS reception in size- and cost-constrained consumer and industrial GPS applications.

FAQ

What is the recommended input matching configuration for SMA661ASTR?

The SMA661ASTR integrates complete input matching circuitry; only a single 100 nF DC-blocking capacitor is required between antenna and Pin 1 (RF IN). No external inductors, capacitors, or resistors are needed-verified per Figure 2 and Table 2 of the official datasheet.

Does SMA661ASTR require an external voltage regulator?

No. The device operates directly from a 2.4–3.0 V supply applied to Pin 6 (VCC), with typical current draw of 8.5 mA. A local 1 µF ceramic bypass capacitor (C6 on evaluation board) is mandatory for RF stability, but no LDO or regulator is required.

Can SMA661ASTR be used with GLONASS or Galileo signals?

Yes-the device exhibits flat gain (±0.5 dB) and stable NF (<1.3 dB) across 1559–1610 MHz, covering GPS L1, Galileo E1, and GLONASS G1 bands. Performance data in Figures 3–5 confirms broadband suitability beyond GPS-only use.

What is the thermal resistance (θ_JA) of the SOT666 package?

Per STMicroelectronics Application Note AN2872, the SOT666 package has θ_JA = 220 °C/W with standard JEDEC 2S2P board layout. With two thermal vias under the exposed pad (per layout recommendation in Section 4), θ_JA improves to ≤140 °C/W-sufficient for 8.5 mA operation at +85 °C ambient.

SMA661ASTR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: SOT-563, SOT-666

Packaging:: Tape & Reel (TR)

Product Status:: Active

Frequency:: 1575MHz

P1dB:: -

Gain:: 18dB

Noise Figure:: 1.15dB

RF Type:: GPS

Voltage - Supply:: 2.4V ~ 3V

Current - Supply:: 8.5mA

Test Frequency:: 1.575GHz

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-666

SMA661ASTR FAQ

1.How can I place an order for SMA661ASTR through Aetrix?

Please submit a Request for Quotation (RFQ) for SMA661ASTR 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 SMA661ASTR reliable?

The price and inventory of SMA661ASTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SMA661ASTR is usually 5 days.

3.What payment methods are accepted for SMA661ASTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SMA661ASTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SMA661ASTR?

SMA661ASTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SMA661ASTR 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 SMA661ASTR?

For technical support, including SMA661ASTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SMA661ASTR requirements.

6.How does Aetrix verify that SMA661ASTR is sourced from the original manufacturer or authorized distributors?

All SMA661ASTR 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 SMA661ASTR meets industry standards.

7.What is the process for return or replacement of SMA661ASTR?

All SMA661ASTR units undergo pre-shipment inspection (PSI). If there is an issue with SMA661ASTR, 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 SMA661ASTR part is unused and in its original packaging.

Return procedure for SMA661ASTR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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