1 Principles of radio transmitters and receivers Dr Ding JiaXin Engineer of Radio Monitoring Division State Radio Monitoring Center dingjiaxin ***@.cn +8610-68312933 Radio Monitoring and Spectrum Management Training (China,23-31,May,2005) 2 Contents: 1. Introduction 2. Basic concepts 3. Radio transceiver architectures 4. Amplifiers 5. Mixers 6. Oscillators 7. Modulation and Demodulation 3 Position of oscillator: 4 Function of oscillator: ? Generate a periodic output ? Provide stable and accurate frequencies for mixer 5 Classification of oscillators: ? Feedback oscillator ? Negative resistance oscillator 6 Principle of feedback oscillator: ? Overall transfer function ? Loop gain: )(1 )()( )(fH fHfX fY?? I FV VT? 7 Barkhausen ’s criteria ? The loop gain must be equal to unity ? The total phase shift around the loop must be equal to zero 8 Frequency work: ? Resonator 9 Oscillator characteristics: ? Accuracy ? Stability 10 Definition of accuracy: ?f x : actual frequency ? f 0 : nominal frequency 00 0f ff ff x???= ?
