| 摘要 |
PURPOSE:To start surely oscillation for a positive feedback oscillation system, by forming a start signal based on a stop state signal and passing through an input signal of a hysteresis element. CONSTITUTION:When a VCO oscillation system stops the oscillation and a positive component S23 and a negative component S23' of an output signal S24 are fixed to an unbalanced voltage, a start circuit 53 turns on a switch circuit 54, locks a voltage of a phase shift controlling signal S22 from a low pass filter 49 and the phase shift circuit 41 to ground potential, making a Schmitt circuit 61 of the circuit 41 forcedly inoperative and passes through phase shift input signals S21, S21' to a limiter amplifier circuit 43. Thus, if even a minute output exists at an output terminal of a narrow band filter 45, the VCO oscillation amplifies the output at amplifiers 42, 43 sequentially and feeds back the result to the input terminal of the filter 45. Thus, when the VCO oscillation system stops the oscillation, a positive feedback system is surely started. |
