EEL3923C Design 1 Electrical and Computer Engineering Analog Amplifier Module Electrical and Computer Engineering 2 Source: “Amplifier Selection Guide,” Texas Instruments, 1Q 2003 Sensor/ Instrument Information System Output What needs analog amplification? Block Diagram of Generic Electronic System Electrical and Computer Engineering 3 Source: “Amplifier Selection Guide,” Texas Instruments, 1Q 2003 Strain gauge Thermistor Microphone What needs analog amplification? Audio Video Electrical and Computer Engineering 4 Input Output Output Input Amp uses: • Signal conditioning • Amplification • Filtering • Buffering • Signal Operations Source: “Amplifier Selection Guide,” Texas Instruments, 1Q 2003 Electrical and Computer Engineering Example system with amplification stages (Tucker Davis Technologies) 5 Processor Neural signals ( uV ) PreAmp Video Output (real - time) Instrumentation Amp • High gain • Low noise • Some frequency filtering Video Amp • High - speed Electrical and Computer Engineering 6 The Big Picture Electrical and Computer Engineering 7 To Which Sector will You Contribute? Electrical and Computer Engineering Amplifier Specifications 8 • Rail - to - Rail (or not) • Gain Bandwidth Product • Slew Rate • Operating Voltage • Max Operating Temp • Operating Supply Current • Common Mode Rejection Ratio • Operating Supply Current • Input Referred Noise • Mounting Style *Choose specs for design application Electrical and Computer Engineering Amplifier Specifications § Gain Bandwidth Product (voltage - feedback amps) 9 Source: https:// www.electronics - notes.com /articles/ analogue_circuits /operational - amplifier - op - amp/gain - bandwidth - product - frequency - response.php Electrical and Computer Engineering Assignment (Analog Amplifier) 10 Part 1 : Objective: Design a small signal amplifier with the following performance criteria and constraints. a) Your amplifier will provide an approximately constant gain of 26 dB from f L =100 Hz to an f H of at least 15 kHz (*you do not need to make an active filter). b) You must use one of the following operational amplifiers: LT1490 or LT1632 c) You may only use a single power supply but you can specify the voltage. d) The input to your amplifier must be capacitively - coupled e) Use the inverting configuration for your op - amp circuit. f) Assume the load for your amplifier is an open circuit. Electrical and Computer Engineering 11 Part 1 : Design and Demonstration • Simulate the circuit in LTSPICE and verify that it meets the performance criteria • Use AC Analysis in LT spice to show frequency response (Bode plot) • Use Transient analysis with input of 100 mV sine - wave plus a 1 V DC offset at a mid - band frequency • Build the circuit on your breadboard • Measure and demonstrate your circuit with (a) Open circuit load, (b) 8 Ohm speaker • Use the Network analyzer function in Waveforms (DAD board) • Use o - scope with input of 100 mV sine - wave plus a 1 V DC offset at the low cut - off frequency f L and a mid - band frequency Assignment (Analog Amplifier) Electrical and Computer Engineering 12 Part 2 : Demonstration • Build a circuit that uses the LM386 audio amplifier IC • Look up IC data sheet for configuration information • Measure and demonstrate your circuit with (a) open circuit load and (b) 8 Ohm speaker • Use the Network analyzer function in Waveforms (DAD board) • Use o - scope with 100 mV sine - wave plus a 1 V DC offset at the low cut off frequency f L and a mid - band frequency Assignment (Analog Amplifier – Signal Conditioning for Audio Output) Electrical and Computer Engineering 13 Questions to Answer • Which op - amp did you choose for Part 1 and why? • How do the voltage and power gains for the LM386 connected to the speaker compare to the voltage and power gains of your op - amp circuit with the speaker connected? • What are the pros/cons of the LTnnnn (op - amp) versus LM386 for precision small - signal sensor amplification? Audio amplification? • Optional: Connect an audio source to both amplifiers, i.e.mp3 player, cell phone, etc., using a 1/8” microphone jack and listen to the output from the speaker with each circuit. How do they sound? Assignment (Analog Amplifier – Signal Conditioning for Audio Output) Electrical and Computer Engineering References to Get Started § https:// www.ieee.li /pdf/essay/ single_supply_op_amp_design.pdf § “Analog Eng Cookbook - OpAmps ” § Op - amp & filter configurations § Design guidance for component values § “ op_amps_everyone.pdf ” § Book containing review of circuit theory § Op - amp & Filter configurations § “Selection Guide_TI_Burr - Brown.pdf ” § Specific op - amp ICs § “ Design_guide_instrument_amps.pdf ” § Instrumentation vs. Difference Op - Amps 14 Electrical and Computer Engineering Amplifiers are Awesome!