| 摘要 |
A circuit is provided for an oscillator circuit comprising a differential amplifier such as an ECL line receiver which directly, in one step outputs a symmetrical square wave signal. This is obtained by means of a symmetrical connection of the bias voltage to the input terminals of the ECL-line receiver through two substantially equally large resistors. A feedback loop comprises, as is conventional, a crystal and a trimming capacitor or a capacitor which may be controlled in some other way as well as a resistor. The capacitor will together with the resistor form a low-pass filter for the control of the oscillating condition of the circuit. Further, an overtone synthesizer is provided adapted to generate even multiples of the frequency of an input signal and it comprises a second ECL line receiver, the positive and negative output terminals of which are directly connected to each other. With appropriate voltage levels of the input signal, an output signal is obtained containing spikes or dips which are repeated at a frequency corresponding to the double frequency of the input signal. From this signal, harmonic components may be obtained having frequencies corresponding to even multiples of the input signal frequency. For the filtering of a chosen multiple a LC-network may be used and for the shaping of the signal another ECL line receiver is used, on the output terminals of which a square wave having ECL-levels is obtained. When the overtone synthesizer is built into the same unit as the oscillator above a very simple circuit is obtained which is not costly, is easily used in other applications, has a high output frequency and has an output signal of well defined levels. |
