I need help with the following question:

For the circuit in

If the output transistor is charged with capacitor

Given data:

Note: This is not homework, I am practicing for exam.

We consider the static analysis of a circuit (low and high logic level).

Note: I assumed that diodes are idealized (when it is forward biased the voltage is 0.6V, and when it is reverse biased, it is an open branch).

1. Low logic level (

We don't consider this case because we can never have

Is this correct?

2. High logic level (

We conclude that at least one input diode is forward biased.

Fourth diode (that is connected to emitter of input voltage) is reverse biased.

Output transistor is on. We need to check if it is in saturation state.

The condition is

Is this correct?

Where to connect capacitor

What is the value of

How to determine the logic function of this circuit?

For the circuit in

**attach 1**, determine the logic function and minimum resistance value of the resistor**Rcmin**such that the output transistor is in saturation state when it is on.If the output transistor is charged with capacitor

**Cp=220nF**, determine the fall and rise time of the output voltage.Given data:

**βmin=50,****β**=100, Vcc=5V, Ubet=0.5V, Ubes=0.7V, Ube=Ud=0.6V, Uces=0.2V.Note: This is not homework, I am practicing for exam.

**Attempt:**We consider the static analysis of a circuit (low and high logic level).

Note: I assumed that diodes are idealized (when it is forward biased the voltage is 0.6V, and when it is reverse biased, it is an open branch).

1. Low logic level (

**Vin=0V**)We don't consider this case because we can never have

**Vin=0V**.Is this correct?

2. High logic level (

**Vin=Vcc=5V**)We conclude that at least one input diode is forward biased.

Fourth diode (that is connected to emitter of input voltage) is reverse biased.

Output transistor is on. We need to check if it is in saturation state.

The condition is

**Ics>Ib/**. We can find**β**min**Ib**as**Ib=Ubes/5k=0.14mA**and**Ics**as**Ics=Uces/Rcmin**. This gives that**Rcmin>200/7 ?**.Is this correct?

Where to connect capacitor

**Cp**and how to find fall and rise time of**Vout**?What is the value of

**Vout**in this case?How to determine the logic function of this circuit?

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