Patent ID: 8217692
Filing Date: 2012-07-10
Classification: H03L

Abstract:
1. A frequency synthesizer, comprising: a reference fixed frequency divide-by-d divider having an input accepting a reference frequency signal, f an output fixed frequency divide-by-d divider having an input that accepts an initial frequency signal, f a first controlled switch bank having an input and a capacitively coupled output, wherein the capacitively coupled output of the first controlled switch bank comprises a first capacitor C a second controlled switch bank having an input and a capacitively coupled output, wherein the capacitively coupled output of the second controlled switch bank comprises a third capacitor C a transconductance amplifier having a first polarized input, a second, oppositely polarized input, and a capacitively coupled transconductance amplifier output; a first charge pump having inputs accepting the reference frequency signal, f where C 1 =C 2 , I 1 is the current output of the first charge pump and T ref is the period of the reference frequency signal f ref , a second charge pump having inputs accepting the initial frequency signal, f where C 3 =C 4 , I 2 is the current output of the second charge pump and T 0 is the period of the initial frequency signal f o ; a voltage controlled oscillator having a frequency control input connected to the transconductance amplifier output, and a pair of outputs, the outputs being the initial frequency f wherein the capacitively coupled transconductance amplifier output has an output current of such that I z charges or discharges a fifth capacitor C 5 to adjust its voltage to the proper value, the controlled oscillator output having a frequency of wherein g m is a transconductance value of the transconductance amplifier, and the fifth capacitor C 5 has a capacitive value of the capacitively coupled transconductance amplifier output.