Digital phase meter and phase detection method

摘要

The disclosed circuit measures the phase difference between two RF signals. The RF signals are compared digitally in an EXOR gate circuit and integrated over the phase comparison period. There are two such EXOR circuits. The input signals may be converted to differential signals by the input buffers and applied to both EXOR circuits. Each EXOR phase detector circuit (fig.2) may include an integration capacitor (C1, fig.2). Asymmetry between the upper and lower parts of the gate circuit of fig.2 may result in the non-triangular shape of the EXOR output curves, shown in fig.3a. In the present invention, the RF signals are applied to two EXOR gates, in A and B channels, as shown in fig.1. The resultant analogue signals (fig.3) are digitised. When the A & B channels are averaged, a near triangular output curve results (fig.3b). Two D-Type registers are used to resolve the (0° to 180°) or (180° to 360°) phase ambiguity of the EXOR based detectors. The circuit is suitable for integration into a single MMIC and may find application in Electronic Warfare (EW) applications.