How is width and lenght of a mosfet is calculated ?
Answers
Answer:
hi
Step-by-step explanation:
The gate length specified for a MOSFET technology means the MINIMUM length. In design it can be larger than the minimum length.
2. The W/L ratio is linked to the trans-conductance and the current capability, together with the multiplicity factor m. A higher w/l ratio increases the current gain and subsequently a higher current for a given Vg. The same is for a higher m that means m·W/L.
3. In practice, for the gain stages are useful large transistors, i.e. large W/L ratios or/and large m. As example, the differential input stage of OpAmps needs high gain. However, the good matching of the input differential stage has to be considered as well.
4. In the current mirrors, a higher transistor gate length is beneficial, for a better matching of the mirror’s currents. You can play with these parameters in simulations to observe the impact of the length on the mirrors current matching.
5. In general, a larger transistor ensures a better matching because it minimizes the edge effects, but this is paid with a significant area price.
OR
http://electronics.stackexchange.com/questions/29902/w-l-ratio-of-a-mosfet
OR
Generally , the minimum W/L ratio of pmos to nmos is 2.5 times.
But in order to have smooth performance , the W/L ratio of pmos is usually kept higher than 2.5.