Making vector network analysis accessible
The PicoVNA 106 is a professional USB-controlled, laboratory grade vector network instrument of unprecedented performance, portability and affordability. Despite its small size and low cost, the instrument boasts a ‘Quad RX’ four-receiver architecture to eliminate the uncorrectable errors, delays and fragility of three-receiver designs with internal transfer switches.
The PicoVNA 106 offers exceptional dynamic range of 118 dB and only 0.005 dB RMS trace noise at its maximum operating bandwidth of 140 kHz. It can also gather all four s-parameters at every frequency point in just 190 µs; in other words a 500 point 2-port .s2p Touchstone file in less than one tenth of a second. The cost is so low that the PicoVNA 106 could even be used as a cost-effective high-dynamic-range scalar network analyzer! It's affordable in the classroom, small business and even amateur workshop, yet capable in the microwave expert's laboratory.
‘Quad RX’ four-receiver architecture
In a VNA a swept sine-wave signal source is used to sequentially stimulate the ports of the interconnect or device under test. The amplitude and phase of the resultant transmitted and reflected signals appearing at both VNA ports are then received and measured. To wholly characterize a 2-port device under test (DUT), six pairs of measurements need to be made: the amplitude and phase of the signal that was emitted from both ports, and the amplitude and phase of the signal that was received at both ports for each source. In practice this can be achieved with a reasonable degree of accuracy with a single source, a transfer switch and two receivers; the latter inputs being switched through a further pair of transfer switches. Alternatively three receivers can be used with an additional input transfer switch or, as in the PicoVNA, four receivers can be used. Using four receivers eliminates the receiver input transfer switch errors (chiefly leakage and crosstalk) that cannot be corrected. These residual errors are always present in two- and three-receiver architectures and lead to lower accuracy than that of the Quad RX design.