The NRO circuit consists of a radio

The NRO circuit consists of a radio frequency negative resistance active device and a frequency selective network, such as a radio frequency signal source using a avalanche Diode Gunn Diode. In negative resistance type Oscillatory circuit, the feedback network usually does not appear, but the feedback type Oscillatory circuit must include the positive feedback network. Thus, the feedback network is a sign of the distinction between the two types of oscillatory circuits. Generally, the operating frequency of the feedback oscillator is the middle and low end of the radio frequency, and the operating frequency of the negative resistance oscillator is the high end of the radio frequency. Negative resistance oscillators are more suitable for higher frequencies such as microwave and millimeter wave.