Mixed Signals PDF

MIXED SIGNALS Mixed Signals to detect events or changes in its 2. buffering the output voltage from an electrical - is a system that contains both digital and analog environment and send the or electronic circuit to get the de...

MIXED SIGNALS Mixed Signals to detect events or changes in its 2. buffering the output voltage from an electrical - is a system that contains both digital and analog environment and send the or electronic circuit to get the desired voltage to signals; such system can be an integrated chip, a information to other electronics, the connected load. PCB product, or a system of components. frequently a computer -They all combine together in a hierarchy to come processor. Unit of resistance - ohms (abbreviated Ω) up with a larger device of powerful multi- functionality, like Active Sensors are those which require an Linear Applications of Op-Amp smart phones. external excitation - the output voltage or current which is -systems can be found everywhere, especially in signal or a power signal. directly proportional to either input voltage or consumer electronics that can interact with the Passive Sensors, on the other hand, do not current. outer environment using a variety of sensors. require any external power Non-linear Applications of Op-Amp signal and directly generates output - is one in which the output signal is not Three examples on mixed-signal systems: response. directly proportional to the input signal. Voltage Follower 1. Microcontrollers and SoCs based on conversion phenomenon i.e., the - is an Op-amp circuit whose output voltage Microcontrollers has been the backbone of the input and the output. Some of the straight away follows the input voltage. mixed-signal technologies , well-selected MCU can common conversion phenomena - that is output voltage is equivalent to the save a lot of costs and space, reducing the need Are : Photoelectric, Thermoelectric, input voltage. for external ICs, like operational amplifiers. Electrochemical, Electromagnetic, - Op-amp circuit does not provide any Thermooptic, etc. amplification. System-on-Chips (SoC), particularly Analog- The other names of voltage follower are: - Thus, voltage gain is equal to 1. Mixed-Signal SoCs (AMS-SoC) - Isolation Amplifier - They are similar to discrete emitter follower. - more powerful and usually dedicated to a - Buffer Amplifier common function of - Unity-Gain Amplifier Examples of Linear application of Op-Amp consumer electronics; such as audio/video Applications of Voltage Follower: processing, as found in most 1. Buffers for logic circuits. Inverting amplifiers Bluetooth headsets and IP cameras. 2. In Sample and hold circuits. - (also known as an inverting operational 3. In Active filters. amplifier or an inverting op-amp) 4. In Bridge circuits via transduce -produces an output which is out of phase with Sensor respect to its input by 180 degrees. - is a device, module, machine, or subsystem Voltage follower is implemented in circuits whose purpose is for reasons. Non - Inverting amplifiers 1. isolating purpose - or non inverting op amp Carlet, Lovella Lyca L. 3-BSCPE-B  MIXED SIGNALS uses op amp as main element. detect the change from positive to - is an op amp based amplifier with positive negative or voltage gain. negative to a positive level of a sinusoidal waveform. OHMS LAW Advantages of Voltage Follower - it detects the zero crossing of the applied 1. Provides power gain and current gain. ac signal. 2. Low output impedance to the circuit which uses the output of the voltage follower. Non Zero Crossing Detectors Logarithmic amplifier (log amplifier) 3. The Op-amp takes zero current from the input. -modified level of zero level detector to - is an electronic circuit that produces an 4. Loading effects can be avoided. detect positive signal. output that is proportional to the logarithm of the applied input. Anti-Logarithmic Amplifier (anti-log amplifier) How is the reference voltage be applied? - is an electronic circuit that produces an output Three ways: battery, voltage, zenor diode instrumentation Amplifier that is proportional to the anti logarithm of the - is used to amplify very low-level signals, applied input. Precision Rectifier rejecting noise and interference signals. - also known as a super diode, is a Examples: Integrator Op-amp configuration obtained with one or more Heartbeats - produces an output voltage that is both operational amplifiers in order to have a blood pressure proportional to the amplitude and duration of the circuit behave like an ideal diode and Temperature input signal. rectifier. earthquakes and so on. differentiator circuit produces a constant output Clock Period – this is the time between voltage for a steadily changing input voltage. successive transitions in the same direction, The advantages of the instrumentation amplifier: ie, between two rising or two falling edges. The gain of a three op-amp instrumentation integrator circuit produces a steadily changing amplifier circuit can be easily varied by adjusting output voltage for a constant input voltage. Duty Cycle – this is the ratio of the clock the value of only one resistor Rgain. width to the clock period. The gain of the amplifier depends only on the Voltage Comparator external resistors used. - is a circuit which compares two voltages and Clock Width – this is the time during which The input impedance is very high due to the switches the output to either high or low state the value of the clock signal is equal to a emitter follower configurations of amplifiers 1 depending upon which voltage is higher. logic “1”, or HIGH. and 2 The output impedance of the instrumentation Zero Crossing Detectors Formula of voltage gain: amplifier is very low due to the difference - An op-amp detector that has the ability to amplifier3. Carlet, Lovella Lyca L. 3-BSCPE-B  MIXED SIGNALS The CMRR of the op-amp 3 is very high and that produces a single pulse either positive almost all of the common mode signal will be or The higher the Sampling Frequency, the lower rejected. negative in value the distortion and the better the sound quality. Voltage to Current Converter (V to I converter) DAC - converts the processed digital signal ANALOG TO DIGITAL CONVERTER - is an electronic circuit that takes current as back into the analog signal that It is the number of times that the converter the input and produces voltage as the output. is used by audio output equipment such as samples the analog signal, its a speaker. unit is Hertz (Hz) differentiator ADC- converts the analog signal collected -circuit produces a constant output voltage for a by audio input equipment, such as a steadily changing input voltage. microphone, into a digital signal that can Differential Amplifier be processed by computer. - is a device which is used to amplify the Schmitt Trigger difference between the - avoids the problem in comparator. resistors are scaled to represent voltages applied at its inputs. - is form of comparator circuit that has hysteresis weights for the different input bits. or different input switching levels to change the two types: output between the two states The most inexpensive type of ADC is a 1. Differential amplifiers built using transistors, either Bipolar Junction -invented by an American scientist named Successive-Approximation ADC. Transistors (BJTs) or Field Effect Transistors (FETs) Otto Schmitt Sampling Frequency 2. Differential amplifiers built using Op-Amps. - means the converter is sampling the (I to V converter) analog audio signal and doing analog to Operational amplifiers - is an electronic circuit that takes current as digital conversion at 44000 times per - are linear devices that have all the properties the input and produces voltage as the output. second. required for nearly ideal DC amplification and are therefore used extensively in signal conditioning, three types of clock pulse generation circuits: The performance of ADCs and DACs mainly filtering or to perform mathematical operations Astable – A free-running multivibrator that depends on their Resolution and Speed. such as add, subtract, integration and has NO stable states but switches continuously differentiation. between two states this action produces a train of Resolution of a converter is expressed in -is fundamentally a voltage amplifying device square wave pulses at a fixed frequency. the number of Bit. designed to be used with external feedback Monostable – A one-shot multivibrator that has For an ADC, the Resolution states the components such as resistors and capacitors only ONE stable state and is triggered externally number of intervals or levels which can be between its output and input terminals. with it returning back to its first stable state. divided from a certain analog input range. - is basically a three-terminal device which Bistable – A flip-flop that has TWO stable states An n-bit ADC has the resolution of 1 / 2n consists of two high impedance inputs Carlet, Lovella Lyca L. 3-BSCPE-B  MIXED SIGNALS Enables substantial amplification of an voltage applied at the other input. four different classifications of operational amplifier input signal - comparator produces limited output voltages gain: - When an operational amplifier is combined which can easily Voltage – Voltage “in” and Voltage “out” with an amplification circuit, it interface with digital logic, even though Current – Current “in” and Current “out” can amplify weak signals to strong signals.It compatibility needs to be Transconductance – Voltage “in” and Current “out” behaves like a megaphone where the Verified. Transresistance – Current “in” and Voltage “out” input signal is a person’s voice and the megaphone is the operational amplifier output voltage signal circuit. -from an Operational Amplifier is the difference Enables elimination of noise from an input between the signals being applied to its signal two individual inputs. - By operating as a filter of input signals, the operational amplifier circuit is Infinite – Input impedance is the ratio of input able to extract the signal with the target voltage to input current and is assumed to be frequency. infinite to prevent any current flowing from the source supply into the amplifiers input circuitry ( I Things to conisder in selecting operational IN = 0 ). amplifier 1.Check the operating voltage Open-loop gain is the gain of the op-amp without 2.Check the input signal frequency. positive or negative 3.Check the current consumption. feedback and for such an amplifier the gain will be 4.Check the signal amplification accuracy. infinite but typical real values range from about 20,000 to 200,000. 3 OP- AMP applications: Zero – The output impedance of the ideal 1. Amplification operational amplifier is - The amplified output signal from assumed to be zero acting as a perfect internal the Op Amp is the difference voltage source with no internal resistance so that it can supply as much between the two input signals. current as necessary to 2. Voltage follower the load. 3. Comparator -Operational amplifier compares the What an Operational Amplifier Can Do? voltage applied at one input to the Carlet, Lovella Lyca L. 3-BSCPE-B