A study on SAW voltage‐controlled‐oscillator using a method of vector summation

Abstract

To achieve ultraminiaturization of synthesizers used in mobile radio this paper proposes the use of a SAW‐VCO incorporating a vector summation technique and describes studies regarding the important parameters of frequency purity and wide‐range variability. the SAW‐VCO using the vector summation method would be composed of SAW elements and a variable gain circuit and it can be expected that they would be ultraminiaturized (using monolithic IC technology). This paper focuses on the issues of high purity and wide‐range frequency variability considering the effect that the SAW delay line has on oscillation characteristics and examines, both experimentally and theoretically, the effects that amplitude ripple has on noise characteristics. In experiments in the 800‐MHz band, a frequency variation range of about 0.5% and C/N of 67 ∼ 75 dB were obtained (C is the carrier power and N is the noise in an 8‐ kHz band with 12.5‐kHz detuning).