Abstract: This application describes a method of testing for manufacturing faults and quality of unpopulated or inactive populated electronic printed circuit boards (PCB). This method can be used to develop a new contactless test system (CTS). An electromagnetic field is generated by an energizing plate connected to an AC signal. When a board under test (BUT) is placed within the electromagnetic field, perturbation of the original field by conducting elements on the BUT is solely a function of the geometrical layout of the conducting elements on the BUT. Therefore, measurement of the perturbed electromagnetic field produces a characteristic pattern for the BUT. Such a pattern can then be compared to a known pattern for the same type of board to determine whether the BUT is faulty (shorts or opens) or not faulty. The most distinctive feature of this method is that testing PCBs by this method requires no electrical contact with the BUT due to the use of the energizing plate.

Abstract: An improved circuit for phase noise measurements utilizing a frequency down conversion/multiplier and direct spectrum measurement technique. The circuit is particularly useful for field test environments where laboratory instrumentation is normally not available, and fast and accurate phase noise measurements are required. The phase noise measuring circuit includes a frequency mixer which has a first input signal from a device under test and a second input signal from a reference stable oscillator having ultra low phase noise with a fixed center frequency. The frequency mixer produces a down converted signal comprising the frequency difference signal of the first and second input signals. A lowpass filter passes the down converted signal to a frequency multiplier circuit which produces a second harmonic signal, a fourth harmonic signal, and higher harmonic signals of the down converted signal.

Abstract: This application describes a novel method and its implementation for testing unpopulated and populated electronic printed circuit boards (PCBs). This method can be used to develop a new contactless test system (CTS). While eliminating drawbacks of existing test systems, this method measures electromagnetic near field distribution in the vicinity of a PCB, contactlessly, by using suitable sensors (possibly printed near field planar antennas) and sensitive measuring and processing devices. The electromagnetic fields (EMF) are generated by the distribution of charges and currents on paths and elements of the board under test (BUT). Therefore, accurate and repeatable measurements of these fields produce a specific pattern for the BUT. Such a pattern is then compared to a known pattern for the same type of board to determine whether the BUT is faulty or nonfaulty.