What is CMOS Latchup?
What is Latchup: Latchup refers to short circuit formed between power and ground rails in an IC leading to high current and damage to the IC. Speaking about CMOS transistors, latch up is the phenomenon of low impedance path between power rail and ground rail due to interaction between parasitic pnp and npn transistors.
What is latchup problem?
Latch-Up is a condition where a low impedance path is created between a supply pin and ground. This condition is caused by a trigger (current injection or overvoltage), but once activated, the low impedance path remains even after the trigger is no longer present.
What is latchup in CMOS circuits to avoid Latchup?
Latch-up prevention techniques:
- Putting a high resistance in the path so as to limit the current through supply and make β1 *β2 < 1.
- Surrounding PMOS and NMOS transistors with an insulating oxide layer (trench).
- Latchup Protection Technology circuitry which shuts off the device when latchup is detected.
What is Mosfet Latchup?
More specifically it is the inadvertent creation of a low-impedance path between the power supply rails of a MOSFET circuit, triggering a parasitic structure which disrupts proper functioning of the part, possibly even leading to its destruction due to overcurrent. A power cycle is required to correct this situation.
What is IGBT Latchup?
The description of latchup just presented is the so-called static latchup mode because it occurs when the continuous on-state current exceeds a critical value. Unfortunately, under dynamic conditions when the IGBT is switching from on to off, it may latch up at drain current values less than the static current value.
What are the advantages of BiCMOS?
It follows that BiCMOS technology offers the advantages of: 1) improved speed over CMOS, 2) lower power dissipation than Bipolar (simplifying packaging and board requirements), 3) flexible I/Os (TTL, CMOS, or ECL), 4) high performance analog, and 5) latchup immunity [1.2].
How latch-up can be prevented by guard ring?
Concept of active guard ring to reduce the injected substrate current at the latch-up path of internal circuits during latch-up I-tests. 1.1 V, large current is generated when latchup happens under 5 V power supply. Thus, the occurrence of latchup can be observed by monitoring the current or voltage condition at VDD2.
What is latch-up test?
The goal in IC latch-up testing is to trigger and monitor a potential latch-up event, where the stress pulse activates a parasitic transistor structure within a CMOS or Bi-CMOS process technology.
How is the IGBT turned off?
One of the main advantages of the IGBT transistor is the simplicity by which it can be driven “ON” by applying a positive gate voltage, or switched “OFF” by making the gate signal zero or slightly negative allowing it to be used in a variety of switching applications.
What is the purpose of a guard ring?
Most analog designs use an extended tap structure called a “guard ring”. Guard rings are large taps that completely enclose a group of devices. Guard rings more effectively isolate devices from each other, by creating a low resistance ring in the well/substrate around the group.
How to prevent latch-up in CMOS technology?
A cross-section of CMOS in SOI technology has shown in figure-9. We can use a combination of the epitaxial layer and retrograde well doping together both the techniques together which is also a very effective way to prevent the latch-up issue but the process is a bit complex. These are the ways to prevent latch-up in CMOS technology.
How to prevent latch-up in tapless cell design?
Well tap cells: In tapless standard cell design to prevent the latch-up, we need to tap the n-well to VDD and p-sub to VSS. These well tap cells tap the n-well to VDD and p-sub to VSS.
What is latch-up issue in power electronics?
In the simplest way, the latch-up issue can be defined as a formation of a direct path from VDD to GND terminal in the design, which will cause a huge current flow between the power and ground terminal.
How can we prevent the latch-up issue in mechanical seals?
We can use a combination of the epitaxial layer and retrograde well doping together both the techniques together which is also a very effective way to prevent the latch-up issue but the process is a bit complex. 7. SOI Technology :