Integrator frequency synthesizer

Abstract

This work discusses an alternative technique to design a frequency synthesizer. The proposed technique is based upon a frequency multiplier circuit using an integrator circuit and a standard frequency division using a programmable counter. The reference crystal oscillator circuit generates a symmetrical square wave of frequency U;). The reference square wave is integrated to generate a symmetrical triangular wave. The symmetrical triangular wave is compared with m voltage levels generated from the symmetrical triangular wave. The output of the comparator circuits are XORed to generate a symmetrical square wave of a frequency (m fr) where m is an integer. This circuit is called integrator frequency multiplier circuit. The output of the frequency multiplier circuit is passed through a counter that divides the frequency by an integer (n). Thence the counter output is a symmetrical square wave of frequency (m/n)fr. The output signal can be converted into sinusoidal wave using a wave shaping circuit followed by a low pass Jilter. The circuit is tested experimentally and results are in good agreement with the theoretical values.