| 摘要 |
The invention concerns a voltage-controlled LC oscillator. A series LC resonance circuit L, Q6 is connected between two transistor amplifier stages Q1, Q5, which form input and output circuits with low impedance for the LC circuit. In this way, the series LC circuit is subjected to very low input and output impedances, which improves the signal/noise ratio S/N of the oscillator. Furthermore, thanks to the low input and output impedances, the series LC circuit oscillates even down to very low Q-value for the coil L, wherein the coil can be integrated in a circuit chip. The LC circuit includes an inductance and at least one series circuit for a series circuit of a pn-semiconductor connection between the transistor stages Q2, Q5, so that the pn-semiconductor connection is biased in the blocking direction. An outside control voltage alters the bias in one transistor stage Q2 so that the potential difference between the transistor stages is altered. In this way, the outside control voltage alters the voltage across the indirectly inverted and biased pn-connection and the capacitance of the pn-connection. In this way, the invention achieves an almost complete separation between the outside control voltage and the actual oscillation circuit. <IMAGE>
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