6.002 Demo# 10 ( Load Set up demo#10PG.set) : (Load Set up Demo#10AA.set) IDS vs. VDS Load Line Agarwal/Fall 00 Lectures 10 and 11 Oscilloscope Setup CH V/DIV OFFSET MODE FUNC MATH VERTICAL HORIZONTAL Horizontal: 1 m Acquisition: Trigger: CH4 Waveform Generator Setup Power Supply Setup UNIT WAVE AMP OFFSET FREQ +6 +25 -25 OUTPUT FG2 SIN 50m ~ 100m 0 1 k 2.08 6 on6.002 Demo# 10 ( Load Set up demo#10PG.set) : (Load Set up Demo#10AA.set) IDS vs. VDS Load Line Agarwal/Fall 00 Lectures 10 and 11 Purpose: In this demo, a picture of the MOSFET amplifier behavior is presented by displaying a load line over a set of (premade) MOSFET i-v curves. The load line crosses the family of MOSFET curves in the saturation region, and ends in the ohmic region. By using music as the amplifier input, and by sending the output to a speaker, distortion can be heard when the signal is outside the saturation region. This is seen on the scope as the (partial) load line being in the saturation region (no distortion), in the ohmic region (distortion), or near the cutoff region (distortion/low volume). As a fun and interesting aside, we can show that classical music suffers much more perceptually than does, say, heavy metal. Steps: 1. Having previously aligned the load line with the stored MOSFET curves, use the sinusoid input to show the entire load line. 2. With the input sinusoid set to a small value, turn on the speaker and adjust the bias of the input to show the amplifier behavior for the different MOSFET regions. 3. Repeat the previous step using a classical music signal from the CD player, noting the audio distortion. 4. Switch to heavy metal music, and point out this type of music does not perceptually distort much. (in showing this demo, we have observed that the output to the speaker system of the class loads the circuit and makes it behave strangely. Add a buffer to fix the problem). MOSFET curves, load line, small music signal Description: Small signal circuit models and analysis Load IVCURVE5.WFM from WAVEFORM MEMORY Connect CD output to the input of to EXT2 (Red) cable. Connect CH3 output of MOSFET Amplifier, using a Tee BNC to Mac Amp/Speaker ******************Make sure the FG1 is OFF ( Very important! )*************************** For music use CD1 #10 for the first music; later we play AC/DC (the razor edge) #1 to show that Doesn’t matter where you have the load line it sounds the same! Note: see Fg1 next page schematic diagram and pins being used Cite as: Anant Agarwal and Jeffrey Lang, course materials for 6.002 Circuits and Electronics, Spring 2007. MIT OpenCourseWare (http://ocw.mit.edu/), Massachusetts Institute of Technology. Downloaded on [DD Month YYYY].Note : For Prof. Agarwal load Demo#10AA.set he starting with ONLY a dot by pressing FG2 offset bottom to zero Oscilloscope Setup CH V/DIV OFFSET MODE FUNC MATH VERTICAL HORIZONTAL 1 off 1 3 DC off CH2 − CH3 2 on 1 4.451 DC off F1 ÷ 1k 3 on 2 -670 mV DC on F2 vs CH3 2 -1.97 2.67 3.91 4 off 200 mV 611 mV DC off Horizontal: 1 m Acquisition: Trigger: CH4 Waveform Generator Setup Power Supply Setup UNIT WAVE AMP OFFSET FREQ +6 +25 -25 OUTPUT FG2 SIN 50m ~ 100m 0 1 k 2.08 6 on Trigger: INT Note: We had to use our amplifier and speaker set up because the 10-250 system stop working and also caused our amplifier ( MOSFET ) on demo board to go bad. Note: Use CD#1 Piano music instead violin for Prof. Lang Cite as: Anant Agarwal and Jeffrey Lang, course materials for 6.002 Circuits and Electronics, Spring 2007. MIT OpenCourseWare (http://ocw.mit.edu/), Massachusetts Institute of Technology. Downloaded on [DD Month YYYY].720 2 K CH3 2N7000 (1) * (2)*IDS vsVDSLoad LineTo Amp/Speaker6 Vdc from +2522 FG21 K +6 VdcMake sure FG1 is OFF! (2) *100 uFCDPlayer1413( 13 ) ** Note: # of pins on the PC board and BNC connectors ( ) PinsBNC (2) * (7) * (20 ) * (22) *Note: We don't need pre-amp for this demo. Cite as: Anant Agarwal and Jeffrey Lang, course materials for 6.002 Circuits and Electronics, Spring 2007. MIT OpenCourseWare (http://ocw.mit.edu/), Massachusetts Institute of Technology. Downloaded on [DD Month
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