Academia.eduAcademia.edu

Figure 12 – uploaded by Qamil Kabashi

See full PDFdownloadDownload figure
“ig.10 The logic “1” transfer with an NMOS. The MOS transistors in pass- transistor logic circuits used to transfer logic state between input and output nodes. During logic “1” transfer and “0” transfer the threshold voltage will have impact on level of output voltage and delay times. In Fig.10 is illustrated the logic “1” transfer with an NMOS.

Figure 10 “ig.10 The logic “1” transfer with an NMOS. The MOS transistors in pass- transistor logic circuits used to transfer logic state between input and output nodes. During logic “1” transfer and “0” transfer the threshold voltage will have impact on level of output voltage and delay times. In Fig.10 is illustrated the logic “1” transfer with an NMOS.

Related Figures (33)

Fig. 1 The physical structure of an n-channel enhancement-type MOSFET in perspective view. Key words: Threshold Voltage, MOSFET Parameters, Enhancement-Type NMOS, Impurities, Doped Density, Short-Channel, Narrow-Channel, Voltage Level, Propagation Delay, Critical Values. The value of the gate-to-source voltage Vas needed to create (induced) the conducting channel (to cause surface inversion) is called the threshold voltage (Vi, or V;). The value of the threshold voltage is dependent from some physical parameters which characterize the MOSFET structure such as: the gate material, the thickness of oxide layer ¢,,, substrate doping concentrations (density) N4, oxide—interface fixed charge concentrations (density) N,,, channel length L, channel width W and the bias voltage Voz [1, 2, 5]. Abstract: The aim of this paper is to research the impact of physical parameters which characterize the MOSFET transistors structure on the threshold voltage values and its influence on critical voltage values which characterize digital circuits that contain the MOSFET transistors. The results obtained emphasize the impact of each single physical parameter on the total value of the threshold voltage. By adjusting the values of MOSFET physical parameters the accepted threshold voltage can be achieved. Since the threshold voltage will have influence on critical voltage values which characterise MOS inverters and delay times during transfer logic states between stages, it must be taken into consideration during design phase of logic gates that contain the MOSFET transistors. 2 The threshold voltage on MOSFET- transistors 2.1 The threshold voltage of NMOS- transistors with long-channel
Fig. 1 The physical structure of an n-channel enhancement-type MOSFET in perspective view. Key words: Threshold Voltage, MOSFET Parameters, Enhancement-Type NMOS, Impurities, Doped Density, Short-Channel, Narrow-Channel, Voltage Level, Propagation Delay, Critical Values. The value of the gate-to-source voltage Vas needed to create (induced) the conducting channel (to cause surface inversion) is called the threshold voltage (Vi, or V;). The value of the threshold voltage is dependent from some physical parameters which characterize the MOSFET structure such as: the gate material, the thickness of oxide layer ¢,,, substrate doping concentrations (density) N4, oxide—interface fixed charge concentrations (density) N,,, channel length L, channel width W and the bias voltage Voz [1, 2, 5]. Abstract: The aim of this paper is to research the impact of physical parameters which characterize the MOSFET transistors structure on the threshold voltage values and its influence on critical voltage values which characterize digital circuits that contain the MOSFET transistors. The results obtained emphasize the impact of each single physical parameter on the total value of the threshold voltage. By adjusting the values of MOSFET physical parameters the accepted threshold voltage can be achieved. Since the threshold voltage will have influence on critical voltage values which characterise MOS inverters and delay times during transfer logic states between stages, it must be taken into consideration during design phase of logic gates that contain the MOSFET transistors. 2 The threshold voltage on MOSFET- transistors 2.1 The threshold voltage of NMOS- transistors with long-channel
Fig. 3 The dependence of the threshold voltage Vig on thickness of oxide layer t,, for parametric values of substrate doping density Ny, when N,, = 2*10'°cm?.
Fig. 3 The dependence of the threshold voltage Vig on thickness of oxide layer t,, for parametric values of substrate doping density Ny, when N,, = 2*10'°cm?.
Fig.5 shows the dependence of the threshold voltage Vo on extra p-type impurities which is added into the channel region.
Fig.5 shows the dependence of the threshold voltage Vo on extra p-type impurities which is added into the channel region.
Fig.7 The dependence of the AViy on the length ZL for parametric values of depth x, when Ny = 10'° cm”, Np = 10" cm®, t,, = 20 nm and Vps = OV.
Fig.7 The dependence of the AViy on the length ZL for parametric values of depth x, when Ny = 10'° cm”, Np = 10" cm®, t,, = 20 nm and Vps = OV.
Influence of the length channel LZ, the depth x; of drain (source) regions and drain-to-source voltage (Vps) on the voltage term AVjo, are shown in Fig.7, Fig.8.
Influence of the length channel LZ, the depth x; of drain (source) regions and drain-to-source voltage (Vps) on the voltage term AVjo, are shown in Fig.7, Fig.8.
Fig.6 Simplified geometry of the MOSFET channel region. Close-up view of the drain diffusion edge.
Fig.6 Simplified geometry of the MOSFET channel region. Close-up view of the drain diffusion edge.
Fig.13 The reduction of high output voltage level by threshold voltage (“poor 1”), when Vi9=1V. Fig.12 The reduction of high output voltage level by threshold voltage (“poor 1”), when Vy=0.6V.
Fig.13 The reduction of high output voltage level by threshold voltage (“poor 1”), when Vi9=1V. Fig.12 The reduction of high output voltage level by threshold voltage (“poor 1”), when Vy=0.6V.
Fig.11 The reduction of high output voltage level (Von) by threshold voltage (“poor 1”), when Vg=0.2V.
Fig.11 The reduction of high output voltage level (Von) by threshold voltage (“poor 1”), when Vg=0.2V.
Fg. 14 Waveform of output voltage V, for logic “0” transfer with one pass-transistor, when V)=0.2V.
Fg. 14 Waveform of output voltage V, for logic “0” transfer with one pass-transistor, when V)=0.2V.
Fg. 15 Waveform of output voltage V, for logic “( transfer with one pass-transistor, when V,)=0.6V.
Fg. 15 Waveform of output voltage V, for logic “( transfer with one pass-transistor, when V,)=0.6V.
Fig. 18 Three identical pass-transistors connected in series. Now consider the following case in which will have three identical pass-transistors connected in series (in cascades) as in Fig. 18.
Fig. 18 Three identical pass-transistors connected in series. Now consider the following case in which will have three identical pass-transistors connected in series (in cascades) as in Fig. 18.
Fig. 19 Waveforms of outputs voltages when three pass-transistors connected in series, when V{9=0.6V.
Fig. 19 Waveforms of outputs voltages when three pass-transistors connected in series, when V{9=0.6V.
Fig. 20 The logic “1” transfers when one pass- transistor is driving another pass-transistor (node voltages during the “1” transfer).
Fig. 20 The logic “1” transfers when one pass- transistor is driving another pass-transistor (node voltages during the “1” transfer).
Fig.21 Waveform of outputs voltages V, for logic “1” transfer, when each pass-transistor (NMOS) is driving another pass-transistor (NMOS) and Vig = 0.6V.
Fig.21 Waveform of outputs voltages V, for logic “1” transfer, when each pass-transistor (NMOS) is driving another pass-transistor (NMOS) and Vig = 0.6V.
The threshold voltage will have influence on critical voltages values which characterize MOS inverters and voltage transfer characteristic. The impact of V; on critical voltages values for a symmetric CMOS inverters are represented in below diagrams (for supply voltage Vpp=3.3V) Fig. 22, Fig. 23, Fig. 24 and Fig. 25.
The threshold voltage will have influence on critical voltages values which characterize MOS inverters and voltage transfer characteristic. The impact of V; on critical voltages values for a symmetric CMOS inverters are represented in below diagrams (for supply voltage Vpp=3.3V) Fig. 22, Fig. 23, Fig. 24 and Fig. 25.
Fig. 23 Variation of Viy (minimum input voltage which can be interpreted as logic “1”) as function of the threshold voltage V;. In symmetric case on CMOS inverters the noise margins for two levels are equal NM; =NMy.
Fig. 23 Variation of Viy (minimum input voltage which can be interpreted as logic “1”) as function of the threshold voltage V;. In symmetric case on CMOS inverters the noise margins for two levels are equal NM; =NMy.
Fig. 25 Variation of propagation delay tp as function of the threshold voltage V; 3.3 Influence of threshold voltage on critical voltage values and delay times in pseudo- NMOS inverters
Fig. 25 Variation of propagation delay tp as function of the threshold voltage V; 3.3 Influence of threshold voltage on critical voltage values and delay times in pseudo- NMOS inverters
Fig. 28 Variation the Vin of pseudo-NMOS inverter as function of the threshold voltage Fig. 27 Variation of the Vj, of pseudo-NMOS inverter as function of the threshold voltage V,.
Fig. 28 Variation the Vin of pseudo-NMOS inverter as function of the threshold voltage Fig. 27 Variation of the Vj, of pseudo-NMOS inverter as function of the threshold voltage V,.
Fig. 26 Variation of the threshold voltage of pseudo- NMOS inverter (Vm) as function of the threshold voltage V,..
Fig. 26 Variation of the threshold voltage of pseudo- NMOS inverter (Vm) as function of the threshold voltage V,..
Fig. 29 Variation of the Vo, of pseudo-NMOS inverter as function of the threshold voltage V,.
Fig. 29 Variation of the Vo, of pseudo-NMOS inverter as function of the threshold voltage V,.
Fig. 32 Variation the les of pseudo-NMOS inverter as function of the threshold voltage
Fig. 32 Variation the les of pseudo-NMOS inverter as function of the threshold voltage
Related topics:
Digital CircuitsLogic GatePropagation delay
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved