| 摘要 |
PURPOSE:To attain continuous changes in an output frequency by inserting a phase shifter controlling the phase shift amount in a delay feedback loop feeding back positively a pulse modulation output to the input side of an amplifier amplifying the output. CONSTITUTION:An output of a variable frequency oscillator VCO1 whose output frequency is controlled by an external control signal is inputted to a pulse modulator 2 and the control from a pulse width controller 3 applies pulse width modulation to the output of the VCO1. A signal obtained by synthesizing (4) between the output of the modulator 2 and the output from a delay line 7 is amplified by an amplifier 5, a part of the amplified output from a distributor 6 is inputted to a delay line via a variable phase shifter 8 to form a delay feedback loop of positive feedback to the amplifier 5. The pole of the transfer function of the delay feedback loop is changed continuously by changing the phase shift of the phase shifter 8 by + or -pi rad to change continuously the output frequency. |
