| 摘要 |
The present invention relates to a Three Point Frequency Modulated System, comprising a phase locked loop frequency synthesizer circuit, see figure, which synthesizes a carrier frequency utilizing a voltage or other electronically controlled oscillator. The circuit comprises a reference frequency source (VCXO,2) which controls the frequency of the Voltage Controlled Oscillator (VCO,40), and a bypassed correcting integrator (58). The circuit has a certain loop bandwidth. A modulating signal (Vm,30) simultaneously modulates the voltage controlled oscillator, the reference frequency source and the bypassed correcting integrator such that the carrier frequency is frequency modulated with a certain frequency deviation. A magnitude matching function and a frequency blending function are also included. The magnitudes of the modulation of the VCO, the reference frequency source and the correcting integrator are controlled over frequency by frequency blending of the reference frequency source and the bypassed correcting integrator utilizing the blending function such that low distortion modulation over a wide frequency range including DC is maintained.
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