In this problem, the goal is to utilise MOSFET\'s current equation to bias the c

Question

In this problem, the goal is to utilise MOSFET's current equation to bias the circuit properly for signal amplification. The amplifier circuit is shown in figure 4. The design requirement is to bias the DC output node Vout at half of Vad and to provide a voltage gain in the range of 1 to 3 (between about 0 to 9dB). For each of the voltage source, Vsig represent AC input, for AC simulation purpose you may set to 1. All other voltage sources are DC sources, with Vdd = 3V. The output resistor is 1k? You'll need to determine the size of NMOS and PMOS and each transistor's gate bias such that node Vout is bias at about 1.5 V, an error of 10 % is allowed. You may changed the size of the de-coupling capacitors as you wish. Do not use transistor size that are less than the minimum resitriction as mentioned in section 2.1 Problem 1.1: Circuit Design Intuition The circuit of figure 4 includes transconductance cell, biasing and output resistance to transform current into voltage Small signal voltage is fed to PMOS producing small signal gmVg, current flowing to the resistor, converting it to voltage signal at resistor node R3. The NMOS wl provide DC bias current given the correct gate bias voltage. Since DC current is required to be the same by KCL, the PMOS bias point is set by the NMOS's DC current. However one must provide the corresponding gate bias voltage for the PMOS to match the NMOS current so that PMOS remains in saturation. Answer the following question a) why is the 10 k? resistor at the gate of PMOS essential needed for proper gain operation ? what would happen to amplifier gain if it is set to 0 2? b) Does the NMOS contributes transconductance gm current at the output? Why? c) What is the function of the capacitors? d) Determine the gain in terms circuit and small signal parameters

Explanation / Answer

Answer:

a) Actually resustre is used To limit or resist tha flow of current, in above circuit the gate resistor 10k is used , and it is connected with voltage aourcs , it means the gate resistor used between voltage source and gate for controlling of voltage and current, and the pmos maximum voltage range is 3 v so for giving particular voltage that means required gate voltage here the 10k resistor is used. If resistor is 0 ohms ,no problem to cirvuic why because the voltage is 0v, but the voltage is above 5v it will be damage the mosfet.

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b)A device mosfet have trans conductance when it is in satiratios region, and mostly mosfet is one type of Transistor and it is used for amplification. In an amplifier circuit the volatgv gain is determined by transistTr small signal transconductance

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c)The actual kperaoper of the capacktoc is to store electric charge, so in this circuit the capacitor ia used to store charge and that charge is used for turn on the mosfet, so qgwh ever the input is hight that time the capacitor goes to charging state and turn on the moafet.

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d) the gain is nothing but total response of the circuit

The gain is calculated using the ratio of output voltage to the input voltage that is

Gain = Vout/Vin;

And the gain tells the system or ciruvic is working good or not

If the gain of the circuit is high that cievcir is working good and best cirvuci

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