National Taiwan University

Shao-Hwa Lee

Sheng-Lyang Jang

Yun-Hsueh Chuang

Ren-Hong Yen

Chun-Chieh Chao

Yun-Hsueh Chang

An injection-locked frequency divider includes a ring oscillator, a signal injection circuit, a first adjustable load circuit and a second adjustable load circuit. The ring oscillator generates an oscillation signal according to a differential signal outputted by the signal injection circuit. According to an adjustable voltage, the first and second adjustable load circuits can respectively change equivalent impedances of the first adjustable load circuit and the second adjustable load circuit so that a free-running frequency of the oscillation signal of the ring oscillator is adjusted and an injection-locked frequency range of the injection-locked frequency divider is expanded.

Injection-locked frequency divider

An injection-locked frequency divider is provided. The injection-locked frequency divider includes a variable reactance unit, a signal injection unit, a first switch, a second switch, a first transformer, and a second transformer. The variable reactance unit, the first switch, the second switch, the first transformer, and the second transformer form a transformer-based LC-tank oscillator. The signal injection unit receives an injection signal. When the injection-locked frequency divider is in a locked state, the transformer-based LC-tank oscillator outputs a frequency division signal. Employing the feedback action of the first transformer and the second transformer, the present invention not only has a wide locking range but also promotes the realization of the low operating voltage.

An injection locked frequency divider includes a signal injection unit, a Hartley voltage controlled oscillator and a biasing unit. The signal injection unit and the biasing unit output an injection signal to the Hartley voltage controlled oscillator to bias the Hartley voltage controlled oscillator. The Hartley voltage controlled oscillator, which includes a first transistor, a second transistor and a LC tank, receives the injection signal and outputs a differential output signal through a first output terminal and a second output terminal. 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. The LC tank decides a resonant frequency of the Hartley voltage controlled oscillator and serves as a positive feedback circuit for the first and second transistors.

Injection locked frequency divider

An injection locked frequency divider includes a ring oscillator, a first injection unit and a second injection unit. The ring oscillator includes a first delay cell and a second delay cell each including differential input terminals and differential output terminals. The differential input terminals and the differential output terminals of the first delay cell are respectively coupled to the differential output terminals and the differential input terminals of the second delay cell. The first injection unit connected between the differential output terminals of the first delay cell receives and injects a first injection signal to the differential output terminals of the first delay cell. The second injection unit connected between the differential output terminals of the second delay cell receives and injects a second injection signal to the differential output terminals of the second delay cell.

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Taipei County, Taiwan

Shao-Hwa Lee