A high precision RF vector analyzer based on synchronous sampling

The authors have developed a RF/microwave amplitude and phase measurement system of exceptional linearity and stability. In the system, the signals to be measured are transformed to discrete time digital signals by synchronous sampling. These digital signals are processed by a digital signal processor for vector detection and for computing digital feedback sent to the sampling gates. The sampling section uses digital feedback to make it insensitive to gain variations of the sampling gates. Digital processing of the IF signals avoids the various IF imperfections of conventional vector analyzers such as gain range errors and detector circularity errors, which explains the exceptional linearity of the system. The operating principles are given, and the design of the system, which works over the frequency range from 10 kHz to 500 MHz, is described