Getting Started : "Overview on 2-Tones Measurement Techniques"
The 2-tones measurement is used to characterized the nonlinearity of an amplifier. When two sinusoidal frequencies are applied to an amplifier, any nonlinear behavior of the amplifier will produce additional frequency components called intermodulation products. For an amplifier with input signals at f1 and f2, the output will contain signals at the following frequencies: nf1 + mf2, where n, m = 0, ±1, ±2, etc. The third-order products, 2f2 – f1 and 2f1 – f2, are a major concern because of their proximity to the fundamental frequencies; and the fact that their power levels increase by a factor of three, relative to an increase in the power level of the fundamental tones. Additionally, their proximity to the fundamental frequencies precludes their removal by filtering. The main figures of merit for intermodulation distortion are Carrier to Nth Order Intermodulation Ratio (C/In) and Nth order Output Intercept Point (OIPn).
Through IQSTAR, several method can be use to generate 2-tones signal and two different method can be use to measure 2-tones : Scalar using a spectrum or Vectorial using a VNA.
2-tones Measurement using PNA-X including Frequency offset and second internal source / internal combiner options
Using high-end VNA such as PNA-X A or B Version including frequency offset (Option 080 or S93080A) and internal second source / internal combiner (option 422 or more), IQSTAR Driver will automatically handle the VNA configuration (switching automatically the internal RF path) in order to generate and measure 2-tones signal.
IQSTAR schematic setup is the following :
2-tones Measurement using 4-Ports PNA including Frequency offset option and internal second source but without internal combiner
Using 4-Ports PNA not including internal combiner, 2-tones signal has to be combined through an external combiner.
In this case, an external RF source has to be defined in IQSTAR setup.
IQSTAR settings :
IQSTAR schematic setup is the following :
2-tones Measurement using 2-Ports PNA including Frequency offset option without internal second source and internal combiner
Using 2-Ports PNA not including internal combiner ad second internal source, 2-tones signal has to build with an external RF source and combined through an external combiner.
IQSTAR settings :
IQSTAR schematic setup is the following :
2-tones Measurement using 2-Ports PNA including Frequency offset & External Vector Signal Generator
IQSTAR settings :
IQSTAR schematic setup is the following :
