ELEC5180: RF/Microwave Circuit Design and Measurement Course ...

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Rejection of image versus suppression of interferers for (a) high IF and (b) low IF: trade-off between sensitivity and selectivity High-IF Low-IF ELEC5180, Kevin Chen, HKUST 21 Front-end components – a list For receivers, we require the following elements: • Antennas • Transmission lines to interconnect the antenna and other circuit elements • Impedance matching circuits • RF filters • Low noise RF amplifiers • Frequency converting mixers • Local oscillators, possibly included frequency multipliers and phase-lock loops • IF filters • IF amplifiers • Demodulators • Nonreciprocal isolators (circulators) For transmitters, we may also require additional elements: • Power amplifiers • Modulators • Transmit-receive isolating switches and diplexers ELEC5180, Kevin Chen, HKUST 22 Relatively New Wireless Systems • Bluetooth: RF-based (2.4 GHz), short-range connectivity solution for portable personal devices. • Wireless LAN Systems: provide high-rate data communication over a small area. Unlicensed. – IEEE 802.11 b, a, and g in the US – HiperLAN in Europe. – Data rate up to 54 Mb/s • 3G/4G Cellular Systems: provide high-speed data and multimedia capability, in addition to voice transmission RF/microwave system-on-chip or system-on-package components are keys to the realization of these systems Power consumption of a bluetooth transceiver is less than 3% of a mobile phone. ELEC5180, Kevin Chen, HKUST 23 ELEC5180, Kevin Chen, HKUST 24
Resonant Circuits and Quality Factor • Various applications: filters, oscillators, frequency meters, and tuned amplifiers, etc. • microwave resonators of all types can be modelled in terms of equivalent RLC resonators (either in series or in parallel). • A resonator is a component which exchanges energy between two or more forms: for electrical circuits, the exchange is between the magnetic field energy storage and electrical field energy storage. • The energy exchanges takes place most efficiently at one particular frequency, called the resonant frequency • Q-factor: the total energy stored divided by the loss of energy during one exchange. • Resonant electrical circuits are often called tank circuits ELEC5180, Kevin Chen, HKUST 25 1. Series Resonant Circuit 1 Z in = R + jωL − j ω C The complex power delivered to the resonator is 1 * 1 2 1 2 1 Pin = VI = Zin I = I ( R + jωL − j ) 2 2 2 ωC R: dissipate power 1 2 P loss = I R 2 L: store magnetic energy 1 2 W m = I L 4 C: store electric energy 1 2 1 2 1 We = VC C = I 2 4 4 ω C So, we have P = P + jω( W −W ) in loss 2 m e ELEC5180, Kevin Chen, HKUST 26 Then Z in can be written as 2Pin Zin = = 2 I At resonance, W m = W e , then we have and ω 0 = 1 LC Where ω 0 is the resonant frequency. At resonance, the resonator looks like a short circuit for a high-Q resonator. P loss Z + 2 jω( W I 2 2P I 2 m loss in = = 2 −W ) R e Quality factor: Q Low loss implies higher Q. For the series resonant circuit and at resonance When ω = ω o +Δω and Q = ω 0 L R Z in (average energy stored) Q = ω (energy loss/second) Wm + W = ω P loss e 2W m ω0L 1 Q = ω 0 = = P R ω RC loss Q increases as R decreases. ≈ R + j2LΔω ≈ R(1 + 0 Δω j2Q ) ω 0 ELEC5180, Kevin Chen, HKUST 27 ELEC5180, Kevin Chen, HKUST 28
Page 1 and 2: ELEC5180: RF/Microwave Circuit Desi
Page 3 and 4: What is special about RF/microwave
Page 5: Dynamic range of the signals: Pmax/
Page 9 and 10: Resistor: besides its resistance, p
Page 11: Spiral inductors: can be convenient

ELEC5180: RF/Microwave Circuit Design and Measurement Course ...

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