External reference clock


UmVXO is a daughterboard for UmTRX SDR transceivers which allows you to change its reference clock, without soldering and with almost no impact on the UmTRX overall dimensions.


UmVXO features high quality temperature-compensated voltage-controlled crystal oscillator (TCVCXO) with the same parameters as the onboard UmTRX TCVCXO, but with a different frequency.

You can also synchronize clock and 1PPS signals of up to 4 UmTRXs with the single UmVXO to achieve up to 8×8 MIMO.

Buy now

Hardware Features

  • Female plug for UmTRX v2.2 or v2.3.1 AUX RF connector
  • Onboard TCVCXO 30.72 MHz clock oscillator (20, 25, 26 and 40 MHz upon request), tunable from UmTRX (GPSDO function)
  • Four reference clock signal distribution outputs
  • 1PPS synchronization signal distribution outputs
  • Ultra low noise LDO DC regulator for better possible specifications


Physical dimensions29 mm x 17 mm x 7 mm
Power Supply voltage range+5.5V typical, +4 to +6.5 V max
Power Supply current, w/o CLK loads< 50 mA
Power Supply current, all CLK outputs loaded< 200 mA
DC regulator noiseRMS - 9 uV
Power Supply supression ratio (PSSR)> 40 dB (10 Hz to 4 GHz)
Output frequency30.72 MHz (20, 25, 26 and 40 MHz upon request)
Frequency stability±280 ppb (±0.28 ppm) at -40°C to +85°C
Tuning DAC resolution12 bit, 0 to 3.3V (~0.8 mV LSB)
TCVCXO Aging (20 years @+25°C)±3 ppm typical, ±4.6 ppm max
TCVCXO frequency tuning range±10 ppm typical, ±7 ppm min
Maximum Phase Noise (30.72 MHz) at 10Hz carrier offset -85 dBc/Hz
Maximum Phase Noise (30.72 MHz) at 1kHz carrier offset-130 dBc/Hz
Maximum Phase Noise (30.72 MHz) at 10kHz carrier offset-135 dBc/Hz
Maximum Phase Noise (30.72 MHz) at 100kHz carrier offset-140 dBc/Hz
RMS Jitter (12kHz to 20MHz BW)~ 1 pS
Logic level of outputsLVCMOS 3.3V

Buy now