Simulations: DC, AC, Tran as Necessary - Instrumentation Amplifier | ECEN 3314, Lab Reports of Electrical and Electronics Engineering

Download Simulations: DC, AC, Tran as Necessary - Instrumentation Amplifier | ECEN 3314 and more Lab Reports Electrical and Electronics Engineering in PDF only on Docsity! Prelab Requirements Data Sheets – Complete NO 1st pages Theory and objective Implementation with expectations Simulations: DC, ac, TRAN as necessary Test Plan - including schematics and data tables Planning and Studying are your responsibility Sections Requiring – Inverting, non-inverting, instrumentation amplifier, integrator, and differentiator. Example Section for the Instrumentation amplifier Instrumentation Amplifier Theory An instrument amplifier is a two stage amplifier consisting noninvering buffers and a differential amplifer. Amplifiers of stage 1 (K1) are connected as noninverting buffers to provide high impedance and excellent common mode rejection ratio. Stage two K2 is connected in a differential amp configuration to remove common mode signals and further amplify the desired difference signal. Using the gain formulas for the noninverting configuration for amplifiers K1 and both inverting and non inverting knowledge for stage 2 or K2 the system gain can be derived as well as the projected bandwidth. Significant Equations GBP = fun = 2 MHz = Avol x f3dB = f3dB x Kx Knon = RF/RI +1 Kinv = -RF/RI Analysis schematic RF1 RF2 RF1 RI1 RI1 RI2 RF2RI2 Vi- = vi1 Vi+ = vi2                  iiii VVRI RF RI RF KKVKKVVo 2 2 1 1 12121              2 2 2 1 1 11 RI RF K RI RF K Vo Vo1=vi1+ vo2 vi2 Note in this example the values for R11, R12 and R13, R14 have been incorrectly determined! The difference between resistor pairs needs to be less than 10%. This error points out both the strength and weakness of simulation. LOST POINTS Note Vin_1 – Vin_2 equals approximately 90 mV but are not of equal magnitude. This is incorrect! Vin _1 should be +/- 50mV and Vin_2 should be -/+ 50mV giving a fully differential signal of +/- 100 mV. AC simulation result The small signal ac simulations are carried out to determine small signal gain and bandwidth and GBP. They are simulated to be 38.5 dB, 134 KHz and 1.1 MHz. Comment –It is important that the low frequency point be show consistent behavior with the 3dB point, 38.5 – 35.5 = 3dB. The expected 3 dB frequency is 134 KHz verses 2 to 3 MHz/21 = 95 to 143 KHz. Simulation looks potentially good! The simulated gain is 84 showing poor correlation between design and simulation or is it. This suggests the simulations were carried out with taking the time to double check it the results carefully. The input was not divided into the output when plotted! LOST POINTS! GBP expected = 105 x 100 KHz = 1 MHz; GBP simulated = 84 x 134 1.1 MHz. Transient simulation Transient simulations carried out show the amplifier full scale gain of Comment – No discuss regarding why these simulation were carried out and what they mean. Transient simulations need to include discussions for their purpose. i.e. maximum full scale output at low frequency and 3dB point or clipping output at low and 3dB frequency. One should be demonstrating that the 3dB frequency is the same for both small signal and large signal? Also what the full scale output voltage can be. ---- Lost points!  Test Plan - including schematics and data tables Test plan for Instrumentation amplifier. The expected gain is 105 with a 3dB bandwidth > 90 KHz. The maximum output must be less than +/-15. This requires the input to be less than +/-150mV. 1) Apply a +/-50mV to +/- 75mV and measure the magnitude and phase plot from 50Hz to 10 MHz. 2) Apply a +/-200mV at 1KHz to confirm clipping at +/-15v 3) Apply a +/-200mV at the 3dB frequency and expect to observe +/-200x 105 x 0.707 = +/-10.5V 4) Determine that the small signal 3dB frequency is identical to the large signal 3dB frequency. Apply +/- 10 mV and +/- 200 mV and determine the measured gain. Freq (KHz) Sim Mag Sim Phase Measured Mag Measured Phase 0.05 0.080 0.100 0.200 8000 10000