| 摘要 |
A function generator as for use in a system of compatible quadrature AM stereo approximates the tangent function curve, allowing for the provision of essentially undistorted intelligence signals. A form of differential amplifier, including additional multiple threshold transistor circuits with common collectors and common bases, has at its input terminals a signal related to an angle of modulation and provides an output signal approaching a signal related to the tangent of the angle of modulation, the accuracy of the approximation depending on the number of circuits included. The function generator has the capability of providing other similar functions and of use in other applications. As used for AM stereo decoding, a tangent function output is derived from the phase modulation components of the stereo signal and, when multiplied by the amplitude modulated signal, the stereo difference signal can be derived.
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