Title: Black Box Electronics
1 Black Box Electronics An Introduction to Applied
Electronics in Experimental Physics 2. Analog
BJTs to Opamps University of Toronto Quantum
Optics Group Alan Stummer, www.physics.utoronto.c
a/astummer
2Active BJTs
Class A with four resistors
Class A with negative feedback
3MOSFETs(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 common are N-channel for analog, both for
digital. - Limited in current ID, voltage VDS and power PD.
- Very 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
to 100A.
4Sample FET Transfer Curves
A general purpose 48A, 60V N-FET from Fairchild
(Digikey.ca). http//www.fairchildsemi.com/ds/ND/N
DP6060L.pdf
5NDP6060L Data Sheet Parametric Section
6Basic Q Switching
7Sample Linear FET Circuit
Opamp uses a N-FET to increase current driving
capacity. The opamp can supply only tens of mA
but the laser needs ten times more.
- The opamp can drive the Q1 FET from cutoff
through to saturation. - All of the laser current goes through R2.
- The opamp monitors the R2 voltage.
- The opamp adjusts the FET gate voltage to control
the FET conductance and therefore the laser
current.
8Less 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 (F
control). - Pros High voltage and current. Cons slow,
poor saturation.
9OpAmps(Operational Amplifiers)
_
- Three terminal linear device 2 inputs 1
output (plus 2 power). - Hard Rule The output goes positive if the
input is positive (where input is defined as ve
input relative to ve input).
- Soft Rule The inputs and output can only range
between the rails (the positive and negative
supply pins).
All else is imperfections
10Basic Stable OpAmp
Almost all opamp circuits are a variation on
this. Understand why this is stable and the rest
is easy.
11Sample Difference Amp
Output is difference between the inputs. Taken
from Analog Devices AD8605 data sheets, a very
good device series.
12Sample Instrumentation Amp
Hi-Z (impedance) inputs, difference out, very
fast. Taken from Analog Devices AD8065-6 data
sheets.
13Sample TIA
Current in, voltage out, used for
photodiodes. Taken from Analog Devices AD8605
data sheets.
14Sample Filter
Active low pass filter of Sallen-Key
design. Taken from Texas Instruments OPA2735
data sheets.
15Some OpAmp Errors
16Basic OpAmp Amplifiers
- f-3dB 1 / 2p R1 C1
- In this example
- Av -100K / 10K -10
- f-3dB 1 / 2p 100K 1nF 1.59KHz
- 0V lt Vout lt 5V
- Vin range depends on Vref
17? The End ?
- Next 3. Digital Electronics
- 4. Sample Circuits
- 5. Simulations Spice is your Friend
- 6. Eagle hands on If you can, bring a laptop
with Eagle loaded and the sample schematic and
board. - Then More in depth on anything? Suggestions?