1 Chapter 1 Introduction to Electronics 1 1

1 Chapter 1 Introduction to Electronics 1. 1 Signals 1. 2 Frequency Spectrum of Signals 1. 3 Analog and Digital Signals 1. 4 Amplifiers 1. 5 Circuit Models for Amplifiers 1. 6 Frequency Response of Amplifiers 1. 7 Digital Logic Inverters 1. 8 Circuit Simulation Using SPICE 2021/12/22 J. Chen

1. 1 Signals Parameters in the real world Transducer 传感器/换能器 2 Electrical signal (a) Thévenin form (b) Norton form Signal sources 2021/12/22 J. Chen

1. 2 Time & Frequency-domain expression and spectrum l 3 Sine-wave: temporally and spatially determined by Amplitude, Frequency/Period and Phase 0 (rad/s) Sine-wave voltage signal and its spectrum 2021/12/22 J. Chen

1. 2 Time & Frequency-domain expression and spectrum l 4 Time-varying signal in arbitrary form→FT→sum of sine-waves. Øe. g. 2021/12/22 symmetrical square-wave J. Chen

1. 2 Time & Frequency-domain expression and spectrum l 5 Sine-wave is always used for analysis, design and testing. Frequency spectrum of the periodic square wave 2021/12/22 J. Chen

1. 2 Time & Frequency-domain expression and spectrum l 6 Spectra of some typical signals A Spectrum of CWDM signal (Hz) 0 500 1000 1500 2000 2500 3000 Spectrum of Human Voice 2021/12/22 Spectrum of laser signal J. Chen

7 1. 3 Signals: analog v. s. digital Delay evolution over 24 hours in a optical fiber system for Time/Frequency transfer AD 2021/12/22 DA Code format of the standard IRIG-B(DC) J. Chen

8 1. 4 Amplifiers l Electronic circuits can perform many analog and digital signal processing functions l This course mainly deals with the simplest but most important function——Amplification Direction of signal flow (a) Circuit symbol 2021/12/22 (b) With a common terminal (ground) J. Chen

9 1. 4 Amplifiers l Both voltage and current can be amplified. Hence there are different types, depending on the practical application scenery. l Ø Source, Input and output resistances Ø The gain (V/V, A/A, V/A, A/V) For a particular amplifier, some gains may be less than one. However, the signal power is certainly amplified. 2021/12/22 J. Chen

1. 4 Amplifier: types and key parameters l 10 Amplifier types Ø Signal intension (small signal amp. , power amp. , …) l Ø Signal spectrum (wideband amp. , tuned amp. , . . . ) Ø … Key parameters Ø Gain, input/output resistance, … Ø Bandwidth Ø Linear & Nonlinear distortion, Saturation Ø …. . 2021/12/22 J. Chen

11 1. 4 Power supplies and Biasing l DC sources are required, not only to bias the circuit for appropriate operation, but also to provide power (a) An amplifier with two dc supplies 2021/12/22 (b) Usual form(Simplified) J. Chen

1. 4 Units & Decibel l 12 Decibel (d. B): a dimensionless number in logarithmic scale. 2021/12/22 J. Chen

13 1. 4 Units & Decibel e. g. The lowest audible intensity is about I 0=10 -12（W/m 2）； In general, the sound intensity is expressed in d. B in relative to I 0 as: The maximum sound intensity human beings can bear is about 1（W/m 2）, or 120 d. B。 2021/12/22 J. Chen

1. 4 Symbol convention 14 l e. g. 2021/12/22 J. Chen

15 1. 5 Circuit models for amplifiers l Mathematical description of the device physical characteristics, useful in quantitative analysis. (a) Circuit model for the voltage amplifier 2021/12/22 (b) The voltage amplifier with input signal source and load J. Chen

1. 5 Circuit models for amplifiers 16 Different device has its own model. l A device may have few different models according to the purpose, precision, applications, etc. . l (a) Small-signal circuit model for a bipolar junction transistor (BJT) (b) An alternative small-signal circuit model for the BJT (c) BJT model for high frequency analysis 2021/12/22 J. Chen

17 1. 6 Frequency response of amplifiers l The band of frequencies, over which the gain is almost constant (within 3 d. B) is called the amplifier bandwidth. 3 d. B Typical magnitude response of an amplifier 2021/12/22 J. Chen

1. 6 Frequency response of amplifiers l 18 Frequency response of amplifiers can be evaluated using Basic Circuit Theory Ø Single-Time-Constant (STC) Networks (a) a low-pass network (b) a high-pass network Two examples of STC networks 2021/12/22 J. Chen

1. 6 Frequency response of amplifiers l 19 Single-Time-Constant (STC) Networks low-pass high-pass (a) Magnitude (b) Phase response 2021/12/22 J. Chen

20 1. 6 Frequency response of amplifiers l Classification of amplifiers based on frequency response. (a) Capacitively coupled amplifier (b) Direct-coupled amplifier (c) Tuned or bandpass amplifier 2021/12/22 J. Chen

1. 7 Digital logic inverters l Out of scope l Those, who are going to be engaged in the 21 R&D of electronic circuit related areas, are advised to read the content. l Especially, attention should be paid to Power Dissipation and Propagation Delay. 2021/12/22 J. Chen

22 Chapter 2 Operational Amplifiers 2021/12/22 J. Chen

23 Operational Amplifiers l The Gain open-loop gain. Ø closed-loop gain Ø differential gain Ø l The terminals inverting input terminal(反相输入端) Ø noninverting input terminal(同相输入端) Ø l The 2021/12/22 Common mode rejection(共模抑制比) J. Chen

24 End of Chapter 1 & 2 2021/12/22 J. Chen

Home work l 1. 2, 2021/12/22 25 1. 15, 1. 17, 1. 23, 1. 31, 1. 58 J. Chen