The most accurate standard model, taking into account the diode's internal bulk resistance (
Real PDF problems will ask what happens if one diode fails open or short.
[ r_d = \fracnV_TI_D = \frac1 \times 25mV1mA = 25\Omega ] The AC output voltage is found by treating (r_d) as a resistor in a voltage divider.
VR=I×R=9.3 mA×1 kΩ=9.3 Vcap V sub cap R equals cap I cross cap R equals 9.3 mA cross 1 k cap omega equals 9.3 V The calculated current , which is >0is greater than 0 . The assumption is Valid . Problem 2: Two-Diode Logic Gate Configuration Circuit Description: Two Silicon diodes ( D1cap D sub 1 D2cap D sub 2 ) are connected in parallel to a shared pull-up resistor . The top of the resistor is tied to . The cathode of D1cap D sub 1 is connected to (Ground). The cathode of D2cap D sub 2 is connected to . Find the output voltage ( Voutcap V sub o u t end-sub ) at the node between the resistor and the anodes. Step 1: Assume State. D1cap D sub 1 has its cathode at and its anode pulled high, so it is likely ON . D2cap D sub 2 has its cathode at , making it likely OFF . Step 2: Replace Diodes. Replace D1cap D sub 1 drop source to ground. Replace D2cap D sub 2 with an open circuit. Step 3: Analyze. Because D1cap D sub 1 diode circuit analysis problems and solutions pdf
Application: Suitable for most practical diode circuit problems. C. Piecewise Linear Model (More Accurate)
The diode with the lowest turn-on path clamps the node voltage. Watch the orientation of the diode and battery symbols.
In series circuits, you evaluate the polarity of the DC sources and determine if the anode voltage is high enough to overcome the barrier potential (0.7V). Find the current I and diode voltage VDcap V sub cap D The most accurate standard model, taking into account
5 – I*1k – 0.7 = 0 → I = 4.3mA total. If two diodes share equally, each gets 2.15mA.
): The input voltage goes negative, strongly reverse-biasing the anode. The diode remains . The circuit is an open loop, so Final Output Metrics: Maximum peak output: Minimum peak output: 4. Summary Guide for Quick Review Circuit Type Key Equation / Feature Troubleshooting Tip Series DC Circuit or current is Parallel Diodes Lowest voltage path turns ON first.
For students of electrical and electronic engineering, the diode is often the first non-linear circuit component they encounter. Unlike resistors, diodes do not obey Ohm’s Law; their current-voltage (I-V) relationship is exponential. This non-linearity makes a foundational challenge—and a critical skill. The assumption is Valid
For comprehensive preparation, focus on these application-based problems:
Maintaining constant output voltage.
Assume a state (ON or OFF) for each diode in the circuit based on source polarity.