* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download UniMasr.com_109
Josephson voltage standard wikipedia , lookup
Cellular repeater wikipedia , lookup
Index of electronics articles wikipedia , lookup
Oscilloscope wikipedia , lookup
Flip-flop (electronics) wikipedia , lookup
Audio power wikipedia , lookup
Oscilloscope types wikipedia , lookup
Power MOSFET wikipedia , lookup
Phase-locked loop wikipedia , lookup
Audio crossover wikipedia , lookup
Oscilloscope history wikipedia , lookup
Current source wikipedia , lookup
Surge protector wikipedia , lookup
Regenerative circuit wikipedia , lookup
Transistor–transistor logic wikipedia , lookup
Wilson current mirror wikipedia , lookup
Negative feedback wikipedia , lookup
Two-port network wikipedia , lookup
Analog-to-digital converter wikipedia , lookup
Power electronics wikipedia , lookup
Radio transmitter design wikipedia , lookup
Integrating ADC wikipedia , lookup
Voltage regulator wikipedia , lookup
Current mirror wikipedia , lookup
Wien bridge oscillator wikipedia , lookup
Valve audio amplifier technical specification wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Schmitt trigger wikipedia , lookup
Valve RF amplifier wikipedia , lookup
Operational amplifier wikipedia , lookup
Passive filters Use Passive components (R, L, C) Does not provide gain Bulky inductors for low frequencies (not suitable for integration) RC filters cannot realize Q > 0.5 Filters parameters are coupled (changing one component can change different filter parameters) Cannot realize ideal integrator Integrated Circuits Chip micrograph Wi-Fi Receiver 17mm2 Integrated Inductors Used in GHz range (L in the range of nH) Low quality factor (need Q-enhancement) Value of L (also R & C) not well controlled Operational Amplifier Model: Basic Represented by: A= open-circuit voltage gain vid = (v+-v-) = differential input signal voltage Rid = amplifier input resistance Ro = amplifier output resistance Signal developed at amplifier output is in phase with the voltage applied at + input (non-inverting) terminal and 1800 out of phase with that applied at - input (inverting) terminal. Operational Amplifier Model: With Source and Load RL = load resistance RS = Thevenin equivalent resistance of signal source vs = Thevenin equivalent voltage of signal source R R L and vid vs R id vo* Av R id Ro R id S L R R id L Av vs Rid RS Ro RL vo •Op amp circuits are mostly dc-coupled amplifiers. Signals vo and vs may have a dc component representing a dc shift of the input away from Q-point. •Op-amp amplifies both dc and ac components. Problem: Calculate voltage gain Given Data: A=100, Rid =100kW, Ro = 100W, RS =10kW, RL =1000W Analysis: R R vo id L Av vs Rid RS Ro RL 100kW 1000W 100 82.6 38.3dB 10kW 100kW 100W 1000W Ideal amplifier’s output depends only on input voltage difference and not on source and load resistances. This can be achieved by using fully mismatched resistance condition (Rid >> RS or infinite Rid and Ro << RL or zero Ro ). vo Av id Av vo v A id A = open-loop gain (maximum voltage gain available from the device) Ideal Operational Amplifier Ideal op amp is a special case of ideal differential amplifier with infinite gain, infinite Rid and zero Ro . v v o id A lim vid 0 A If A is infinite, vid is zero for any finite output voltage. Infinite input resistance Rid forces input currents i+ and i- to be zero. Ideal op amp has following assumptions: Infinite common-mode rejection, power supply rejection, open-loop bandwidth, output voltage range, output current capability and slew rate Zero output resistance, input-bias currents and offset current, inputoffset voltage. Inverting Amplifier: Configuration Positive input is grounded. Feedback network, resistors R1 and R2 connected between inverting input and signal source and amplifier output node respectively. Inverting Amplifier:Voltage Gain vs isR i R vo 0 1 2 2 But is=i2 and v-=0 (since vid=v+-v-=0) R vs vo is 2 and Av R vs R 1 1 Negative voltage gain implies 1800 phase shift between dc/sinusoidal input and output signals. Gain greater than 1 if R2 > R1 Gain less than 1 if R1 > R2 Inverting input of op amp is at ground potential (not connected directly to ground) and is said to be at virtual ground . Non-inverting Amplifier: Configuration R R vo vs 1 2 R 1 R v o R1 R2 Av 1 2 R vs R 1 1 • Input signal is applied to the non-inverting input terminal. • Portion of the output signal is fed back to the negative input terminal. • Analysis is done by relating voltage at v1 to input voltage vs and output voltage vo . Unity-gain Buffer A special case of non-inverting amplifier, also called voltage follower with infinite R1 and zero R2. Hence Av =1. Provides excellent impedance-level transformation while maintaining signal voltage level. Ideal voltage buffer does not require any input current and can drive any desired load resistance without loss of signal voltage. Unity-gain buffer is used in may sensor and data acquisition systems. Alternative realization Prone to parasitic capacitance Voltage swing on the input terminals Differentiator v i o R R dvs is C dt Since iR= is dvs vo RC dt • Input resistor R1 in the inverting amplifier is replaced by capacitor C. • Derivative operation emphasizes high-frequency components of input signal, hence is less often used than the integrator. Output is scaled version of derivative of input voltage. Passive realization R 1 sC R 2 11 Av (s) . . R R 1 s(R // R )(C C ) v 1 2 1 2 1 2 in vo Non-inverting realization R R 1 s(R // R )(C C ) 1 2 1 2. Av (s) 1 2. R 1 sC R v 2 11 in vo How to implement RHP zero? R 1 sC R 1 1. Av (s) 2 R 1 sC R v 2 2 1 in vo All-pass filter Low-pass Frequency Response For Q=0.707,magnitude response is maximally flat (Butterworth Filter: Maximum bandwidth without peaking) For Q>0.707, response shows undesired peaking. For Q<0.707: Filter’s bandwidth capability is wasted. At w<<wo, filter has unity gain. At w>>wo response exhibits two-pole roll-off at -40dB/decade. At w=wo, gain of filter =Q. High-pass Frequency Response For Q=0.707,magnitude response is maximally flat (Butterworth Filter response). Amplifier gain is constant at w>wo, the lower cutoff frequency of the filter. Band-pass Frequency Response Response peaks approximately at wo. At w<<wo or w>>wo, filter response corresponds to single-pole high-pass or low-pass filter changing at a rate of 20dB/decade. Single amplifier Biquad (SAB) Enhanced Positive Feedback (EPF) Enhanced Negative Feedback (ENF)