Cmos
CMOS INVERTER: Preliminary Questions and Design
Functional group F94
Basic CMOS Inverter Circuit and Operation of CMOS inverter
Kerk Yi Wern
Basic CMOS inverter Circuit
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Act like a switching circuit Input: High Input: Low NMOS ON , PMOS OFF PMOS ON, NMOS OFF
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Operation of CMOS inverter
Rise/fall time, VTC, Noise margin effects and Threshold Voltage Vm.
Nabilah SK Aziz
→ The propagation delay of the CMOS inverter is determined by the time it takes to charge and discharge the capacitances present in the logic circuit → The two parameters are the high-to-low propagation time,tPHL and the low-to-high propagation time, tPLH. → tPLH is the time measured from the voltage on the falling input waveform to the same voltage on the rising output voltage. → For the low-to-high transition, the n-channel device is cutoff and the p-channel MOSFET is initially saturated and supplying - IDp(sat) to charge up the gate and parasitic capacitances → tPHL is the time measured from the voltage on the rising input waveform to the same voltage on thefalling input waveform. → VIN switches instantly from low to high. Driver transistor (n-channel) immediately switches from cutoff to saturation; the p-channel pull-up switches from triode to cutoff. → TP (propagation delay) = ( tPLH+ tPHL)/2
Output Rise Time (tPHL) and Output Fall Time (tPLH)
VOLTAGE TRANSFER CHARACTERISTIC
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Noise margin is a measure of the circuit's immunity to noise. The high-level and low-level noise margins are represented by VNH and VNL respectively the ability of a logic circuit to tolerate noise without causing any unwanted changes in the output. Also, the quantative measure of noise immunity is known as noise margin.. Digital circuit working with logical Low-level and High-level. There is a noise margin build into the definition. If there is noise(on ground or supply voltage, or crosstalk to inputs) above the tolerable noise margin, you get malfunction or faulty function. Logic Noise Margin
Functional group F94
Basic CMOS Inverter Circuit and Operation of CMOS inverter
Kerk Yi Wern
Basic CMOS inverter Circuit
● ● ●
Act like a switching circuit Input: High Input: Low NMOS ON , PMOS OFF PMOS ON, NMOS OFF
●
Operation of CMOS inverter
Rise/fall time, VTC, Noise margin effects and Threshold Voltage Vm.
Nabilah SK Aziz
→ The propagation delay of the CMOS inverter is determined by the time it takes to charge and discharge the capacitances present in the logic circuit → The two parameters are the high-to-low propagation time,tPHL and the low-to-high propagation time, tPLH. → tPLH is the time measured from the voltage on the falling input waveform to the same voltage on the rising output voltage. → For the low-to-high transition, the n-channel device is cutoff and the p-channel MOSFET is initially saturated and supplying - IDp(sat) to charge up the gate and parasitic capacitances → tPHL is the time measured from the voltage on the rising input waveform to the same voltage on thefalling input waveform. → VIN switches instantly from low to high. Driver transistor (n-channel) immediately switches from cutoff to saturation; the p-channel pull-up switches from triode to cutoff. → TP (propagation delay) = ( tPLH+ tPHL)/2
Output Rise Time (tPHL) and Output Fall Time (tPLH)
VOLTAGE TRANSFER CHARACTERISTIC
●
Noise margin is a measure of the circuit's immunity to noise. The high-level and low-level noise margins are represented by VNH and VNL respectively the ability of a logic circuit to tolerate noise without causing any unwanted changes in the output. Also, the quantative measure of noise immunity is known as noise margin.. Digital circuit working with logical Low-level and High-level. There is a noise margin build into the definition. If there is noise(on ground or supply voltage, or crosstalk to inputs) above the tolerable noise margin, you get malfunction or faulty function. Logic Noise Margin