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Device Overview

The SBX is a wide bandwidth transceiver that provides up to 100 mW of output power, and a typical noise figure of 5 dB. The local oscillators for the receive and transmit chains operate independently, which allows dual-band operation. The SBX is MIMO capable, and provides 40 MHz or 120 MHz of bandwidth. The SBX is ideal for applications requiring access to a variety of bands in the 400 MHz-4400 MHz range. Example application areas include WiFi, WiMax, S-band transceivers and 2.4 GHz ISM band transceivers. The SBX daughterboard is supported by the USRP Hardware Driver™ (UHD) software API for seamless integration into existing applications.

The SBX is capable of phase coherent operation, and therefore is suitable for MIMO and Phased Array applications.

Key Features

  • Frequency Range: 400MHz - 4.4GHz
  • Versions: 40MHz / 120MHz
  • Power Output: 100mW
Product sbx 40.jpg
Product sbx 120.jpg

Daughterboard Specifications


  • 2 quadrature frontends (1 transmit, 1 receive)
    • Defaults to direct conversion
    • Can be used in low IF mode through lo_offset with uhd::tune_request_t
  • Independent receive and transmit LO's and synthesizers
    • Allows for full-duplex operation on different transmit and receive frequencies
    • Can be set to use Integer-N tuning for better spur performance with uhd::tune_request_t


Transmit: TX/RX

Receive: TX/RX or RX2

  • Frontend 0: Complex baseband signal for selected antenna
  • Note: The user may set the receive antenna to be TX/RX or RX2. However, when using an SBX board in full-duplex mode, the receive antenna will always be set to RX2, regardless of the settings.


  • Transmit Gains: PGA0, Range: 0-31.5dB
  • Receive Gains: PGA0, Range: 0-31.5dB


  • SBX: 40 MHz, RX & TX
  • SBX-120: 120 MHz, RX & TX


  • lo_locked: boolean for LO lock state


  • All LEDs flash when daughterboard control is initialized
  • TX LD: Transmit Synthesizer Lock Detect
  • TX/RX: Receiver on TX/RX antenna port (No TX)
  • RX LD: Receive Synthesizer Lock Detect
  • RX1/RX2: Receiver on RX2 antenna port

RF Specifications

Freq Range

  • 400MHz - 4.4GHz

Noise Figure

  • 4 - 5 dB @ (400MHz ~ 1.5GHz)
  • 5 - 7 dB @ (1.5GHz ~ 3GHz)
  • 7 - 12dB @ (3GHz ~ 4.4GHz)

RX IIP3 (Max)

  • 16 ~ 22 dBm

RX IQ Imbalance

  • -20 dBc @ (400MHz ~ 600MHz)
  • -30dBc @ (600MHz ~ 4.4GHz)

TX Power (Max)

  • 20 dBm @ (400MHz ~ 3.5GHz)
  • 18 - 20dBm @ (3.5GHz ~ 4.4GHz)


  • 26 - 30dBm @ (400MHz ~ 1.5GHz)
  • 30 dBm @ (1.5GHz ~ 4.4GHz)

TX IQ Imbalance

  • -20 dBc @ (400MHz ~ 600MHz)
  • -30dBc @ (600MHz ~ 4.4GHz)

Input/Output Impedance

  • All RF Ports are matched to 50 Ohm with -10dB or better return loss generally. Detailed test is pending.

Input Power Levels

  • The maximum input power for the SBX is -15 dBm.

RF Performance Data

Hardware Specifications

  • Ettus Research recommends to always use the latest stable version of UHD


  • Current Hardware Revision: 5.1
  • Minimum version of UHD required: 3.8.0

Environmental Specifications

Operating Temperature Range

  • 0-40 °C

Operating Humidity Range

  • 10% to 90% non-condensing

USRP Compatibility


  • N or X Series


  • X Series only

Phase Synchronization

The SBX daughterboard is capable of phase-synchronous operation, and is recommended for phase-coherent applications. The UBX and TwinRX daughterboards are also recommended for phase-coherent applications.



SBX Schematics

Key Component Datasheets

Part Number Description Schematic ID (Page)
MGA82563 Amplifier U1, U5, U4 (1)
AS225-313LF SPDT Switch U3, U6 (1)
LFCN-5850+ Low Pass Filter FL1 (1)
PHA-1+ Amplifier U8 (1)
GVA-84+ Amplifier U9 (1)
ADL5380ACPZ Quadrature Demodulator U11 (2)
ADA4927-2YCPZ Differential ADC Driver U10 (2)
AD8591ARTZ-REEL Amplifiers U31 (2)
ADF4350BCPZ Synthesizer with Integrated VCO U23 (3); U24 (6)
SKY13267 Diversity Switch U12 (3); U25 (6)
LFCN-1200+ Low Pass Filter FL13 (3); FL12 (6)
TC1-1-43A+ RF Transformer T3 (2); T2, T5 (3); T4, T6 (6)
LP3878MR-ADJ Voltage Regulator U13, U14 (4); U19, U20 (5)
NC7WZ04P6X Dual Inverter U15, U16 (4); U21 (5); U27 (6); U26 (3)
24LC024 EEPROM U17 (4); U22 (5)
ADL5375 Quadrature Modulator U18 (5)


RF Connectors

  • The SBX daughterboard features female SMA connectors for both the TX/RX and RX2 connectors.



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FPGA Resources

UHD Stable Binaries

UHD Source Code on Github