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Black Box Electronics

Black Box Electronics. An Introduction to Applied Electronics for Physicists 2. Analog Electronics: BJTs to opamps University of Toronto Quantum Optics Group Alan Stummer, Research Lab Technologist. Active BJTs. Class A with four resistors. Class A with negative feedback.

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Black Box Electronics

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  1. Black Box Electronics An Introduction to Applied Electronics for Physicists 2. Analog Electronics: BJTs to opamps University of Toronto Quantum Optics Group Alan Stummer, Research Lab Technologist

  2. Active BJTs Class A with four resistors Class A with negative feedback

  3. MOSFETs(Metal Oxide Semiconductor Field Effect Transistor) • Drain to source resistance and/or current ≈ 1 / gate to source voltage. • Zero gate current! • Operate in active region (analog), or saturation or cutoff (digital). • Most are N-channel (source grounded, positive drain and gate). • Limited in current ID, voltage VDS and power PD. • Very good saturation, RDS(on). • Limited frequency range, capacitance dominates at high frequency. • Select for current, voltage, speed and RDS(on) if saturating. • Typical voltage VDS range 10V to 200V, extreme to 1.5KV. • Typical current ID range 100mA to 10A, extreme 10mA to 100A.

  4. Sample FET Transfer Curves A general purpose 48A, 60V N-FET from Fairchild (Digikey.ca). http://www.fairchildsemi.com/ds/ND/NDP6060L.pdf

  5. NDP6060L Data Sheet – Parametric Section

  6. Basic Q Switching

  7. Sample Linear FET Circuit Opamp uses a N-FET to increase current driving capacity. The opamp can supply only ten’s of mA but the laser needs ten times more. • The opamp can drive the FET from cutoff through to saturation. • All of the laser current goes through R9. • The opamp monitors the R9 voltage. • The opamp adjusts the FET gate voltage to control the FET conductance.

  8. Less Common Active Parts • IGBT (Insulated Gate Bipolar Transistor) • Current allowed through collector to emitter is proportional to voltage between gate and emitter. • Voltage controlled like a FET, switches like a BJT. • Used for power control such as motors. • Pros: High voltage and current. Cons: slow, poor saturation. • Thyristers: SCR (Silicon Controlled Rectifier)& Triac • Anode/MT1 connects to cathode/MT2 once gate current exceeds threshold, stays on until anode/MT1 current drops below threshold. • SCR is unipolar, Triac is bipolar. • Used for motor and lighting controls (Φ control). • Pros: High voltage and current. Cons: slow, poor saturation.

  9. OPAMPs(Operational Amplifiers) • Five terminal linear device (2 power, 2 inputs, one output). • Hard Rule #1: The output goes positive if the input is positive (where input is defined as +ve input relative to –ve input). • Soft Rule #2: The inputs and output can only range between the “rails” (the positive and negative supply pins). • All else is imperfections:

  10. Some OpAmp Errors

  11. Basic OpAmp Amplifiers

  12. Ω The End Ω Next: 3. Digital Electronics 4. Sample Circuits 5. Spice simulations Then: More in depth on anything? Suggestions?

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