lect 5 - Inverters AB A B = A 01 10 Boolean value of 1...

Info iconThis preview shows pages 1–9. Sign up to view the full content.

View Full Document Right Arrow Icon
Inverters
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
B 0 1 1 0 A A B = A’ Boolean value of 1 represented by high voltage V DD Boolean value of 0 represented by low voltage 0 V out V th 0 V DD /2 V DD 1 0 V in
Background image of page 2
V DD load I L V out = V DS I D C ou t V in = V GS lumped value Driver transistor I D ( V in , V out ) = I L ( V L ) Voltage transfer characteristics found by solving the equation analytically
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
For very low input voltage output voltage V out is equal to high value of V OH. Driver nMOS is cut-off – no current thro it. As the input voltage Vin increases, the driver transistor starts conducting a certain current, and the output voltage starts to decrease. Vout dVout/dVin = -1 V OH dVout/dVin = -1 V OL Vin V IL V TH V IH
Background image of page 4
The drop in the output voltage is gradual. Two critical points in the graph. dV out /dV in = -1 V IL : Maximum input voltage which can be interpreted as logic ‘0’ V IH : Minimum input voltage which can be interpreted as logic ‘1’ As the input voltage is further increased , output voltage continue to drop and reaches a value of V OL when input voltage is equal to V OH Inverter threshold voltage V th , is the transition voltage is at the point where V in = V out V OL ( min) , V OH (max)
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Resistive load inverter -enhancement nMOS transistor is the driver device. -Load is a resistor R L . Drain current I D = Load current I R Taking V SB = 0 Threshold voltage of the driver transistor is V TO
Background image of page 6
For nMOST I D = 0 for V GS < V T I D (lin) = µ n (C ox /2 )(W/L) [ 2(V GS -V TO ) V DS –V DS 2 ] for V GS > = V T V DS < V GS –V T I D ( sat) = µ n (C ox /2 )(W/L) [ (V GS -V TO ) 2 ] (1+ λ V DS ) for V GS >= V T and V DS >= V GS -V T
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
• For Input voltages smaller than VTO, transistor in CUT –OFF • As the Input voltage is increased beyond
Background image of page 8
Image of page 9
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/24/2010 for the course EEE MEL G621 taught by Professor Gurunarayanan during the Fall '08 term at Birla Institute of Technology & Science, Pilani - Hyderabad.

Page1 / 32

lect 5 - Inverters AB A B = A 01 10 Boolean value of 1...

This preview shows document pages 1 - 9. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online