Patent ID: 7522007

Claim:
An injection locked frequency divider, comprising: a signal injection unit for receiving and outputting an injection signal; a Hartley voltage controlled oscillator for receiving the injection signal and outputting a differential output signal, which has a frequency equal to a divided frequency, through a first output terminal and a second output terminal, the Hartley voltage controlled oscillator comprising: a first transistor and a second transistor, wherein first terminals of the first and second transistors are respectively coupled to the first and second output terminals, and second terminals of the first and second transistors are coupled to a first node; and a LC tank coupled to and between the first output terminal and a control terminal of the first transistor, and coupled to and between the second output terminal and a control terminal of the second transistor to serve as a positive feedback circuit for the first and second transistors, wherein the LC tank decides a resonant frequency of the Hartley voltage controlled oscillator, and a frequency of the injection signal and the resonant frequency are mixed together to generate a frequency equal to the divided frequency of the differential output signal; and a biasing unit for supplying a first current and a second current to the Hartley voltage controlled oscillator to bias the Hartley voltage controlled oscillator.