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Referring to MOS amplifier below, which one of the choices is the small signal voltage gain?

Referring to MOS amplifier below, which one of the choices is the small signal voltage gain?

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Referring to MOS amplifier below, which one of the choices is the small signal voltage gain?

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It is required to bias the MOSFET amplifier shown in Fig. 1 below at point Q for which VOV,Q = 0.2 V and VDS,Q = 1 V. It is required to bias the MOS amplifier of Fig. 7.3 at point Q for which VOV = 0.2 V and VDS = 1 V. Find the required value of RD when VDD = 5 V, Vt = 0.5 V, and kn = 10 mA/V2. Also specify the coordinates of the VTC end point B. What is the small signal voltage gain of this amplifier? Assuming linear operation, what is the maximum allowable negative signal swing at the output? What is the corresponding positive peak input signal?
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In this question, you are asked to find the effective transconductance (Gm) and the resistance into the drain (Rx) of a common-source amplifier with source degeneration. Based on the results, the voltage gain of a common-source amplifier with source degeneration will be evaluated a) The figures shown below are a circuit to find the effective transconductance (G) of the NMOSEFT with source degeneration (left) and its corresponding small-signal circuit (right). It is noted that the output is shorted to VDD (ac grounded) since the definition of effective transconductance is the ratio between the short-circuit output current and the input signal voltage. Prove that Gm is given by Gm = id/vin = gm/1+gmRs In this calculation, the current passing through ro can be neglected since, in general, ro is very large when the NMOSFET operates in saturation region and so this current is very small. Thus, the indication of id is the current of the voltage-controlled current source (gmvgs) only. b) The figure shown below is the method to evaluate the resistance looking into the drain (i.e. Rx) of a source-degenerated NMOSFET. The circuit is shown on the left while the equivalent small-signal modeling is shown on the right. It is noted that the bias condition (VBiAS) is set so that the values of gm and ro, can be defined. Moreover, there is no input signal (i.e. Vin = 0) since we would like to see the value of Rx which is due to the circuit only but not due to the external effect. Based on the above small-signal model, prove that RX = ro(1 + gmRS) The complete common-source amplifier with source degeneration is shown below. c) The complete common-source amplifier with source degeneration is shown below. Prove that the voltage gain of this amplifier is given by v. Vin Explain the reason(s) why the voltage gain is negative. What is the physical meaning of negative voltage gain?

In this question, you are asked to find the effective transconductance (Gm) and the resistance into the drain (Rx) of a common-source amplifier with source degeneration. Based on the results, the voltage gain of a common-source amplifier with source degeneration will be evaluated a) The figures shown below are a circuit to find the effective transconductance (G) of the NMOSEFT with source degeneration (left) and its corresponding small-signal circuit (right). It is noted that the output is shorted to VDD (ac grounded) since the definition of effective transconductance is the ratio between the short-circuit output current and the input signal voltage. Prove that Gm is given by Gm = id/vin = gm/1+gmRs In this calculation, the current passing through ro can be neglected since, in general, ro is very large when the NMOSFET operates in saturation region and so this current is very small. Thus, the indication of id is the current of the voltage-controlled current source (gmvgs) only. b) The figure shown below is the method to evaluate the resistance looking into the drain (i.e. Rx) of a source-degenerated NMOSFET. The circuit is shown on the left while the equivalent small-signal modeling is shown on the right. It is noted that the bias condition (VBiAS) is set so that the values of gm and ro, can be defined. Moreover, there is no input signal (i.e. Vin = 0) since we would like to see the value of Rx which is due to the circuit only but not due to the external effect. Based on the above small-signal model, prove that RX = ro(1 + gmRS) The complete common-source amplifier with source degeneration is shown below. c) The complete common-source amplifier with source degeneration is shown below. Prove that the voltage gain of this amplifier is given by v. Vin Explain the reason(s) why the voltage gain is negative. What is the physical meaning of negative voltage gain?

Solution
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For the following NMOS amplifier (with another NMOS used as a pull-up). The following parameters are for both M1 and M2 transistors: Vdd = 2.5v Vbs = 0 Vt0 = 0.5v lambda = 0.11v-1 W/L = 10 unCox = 200.0 uA/V2 a) For VIN equal to 1.25 V, what region is transistor M1 operating in? Find VOUT . b) For VIN equal to 2.0 V, what region is transistor M1 operating in? Find VOUT. c) Create a small signal model for this circuit. Find open circuit gain AV. d) For VIN equal to 1.25 V, Find the value for open circuit voltage gain, AV. Hint: Need values for gM1, gM2, rOM1, rOM2; combine two small signal models, one for each transistor, to find the final small signal model.
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