Questions tagged [common-source]
A common source is one of the three basic FET topologies. It is distinguished by the fact that the input is at the FET's gate and the output is at the drain, leaving the FET's source as the "common" terminal. It typically exhibits high voltage gain but low bandwidth. Consider also using the "fet" or "mosfet" tag, as applicable.
40 questions
1 vote
2 answers
162 views
Drawing small signal model
I am having trouble learning the correct way to draw a small signal model. I actually have no background in electronics and I am taking this Analog IC course as an elective, so please explain even the ...
- 11
3 votes
1 answer
106 views
How to sketch VOUT vs VIN in this simple NMOS circuit? in DC - Large signal
I have the following circuit: I want to sketch the VOUT vs VIN for VIN from 0-2V. I know that Vg2 = 619mV, and VCC=2V. I start by checking M2 (as I have fewer variables with it). VGS2 = Vg2-0 = Vg2, ...
- 405
2 votes
1 answer
153 views
CS and CD amplifiers
I have to solve an exercise involving a common source + common drain two-stages amplifier. The circuit is this: I cannot find a proper way to calculate Vd of the first transistor (M1). In the DC ...
1 vote
1 answer
69 views
Is amplification possible when biasing a common source stage (NMOSFET) with an ideal current source?
Suppose that we have this common source stage configuration with all the required values in the ideal current source and voltage source for the MOSFET to be in saturation. That is, the ideal current ...
1 vote
2 answers
151 views
setting VDS of transistor to desired value
I'm designing a single transistor common source amplifier using the gm/id method and for the common mode output voltage, I want it to be 0.7. So I have the setting below where I use a vcvs with a high ...
- 21
0 votes
1 answer
47 views
How would the MOSFTET M2 conduct in the given Differential Amplifier?
As per this circuit shown, gate of M2 is grounded. As Vgs=0, M2 won't conduct current as being an NMOS. If that is the case, how would voltage division occur and how does M2 forms a source ...
user411653
5 votes
5 answers
899 views
Biasing common-source NMOS with active load and fixed Vgs
I came across this circuit, a common-source NMOS amplifier with PMOS current mirror as active load AND a fixed DC voltage level at the NMOS gate. Since we're using a current mirror, we are, by ...
- 151
0 votes
0 answers
89 views
Finding the noise due to circuit elements
I am trying to find out the noise referred at the input. Here is how I went about this. I started about by adding up all the current noises due to all elements at output, \$4KTR_F + 4KTR_D + 8KT(g_{...
0 votes
0 answers
105 views
How to perform AC analysis for cascode common source amplifier with resistive load?
I have designed a cascode common-source amplifier with a resistor load π
π· between transistors π1 and π2. I would like to verify if my AC model for this circuit is correct. Additionally, I need ...
- 41
1 vote
2 answers
1k views
Diode-Connected load
What does it mean by a small-signal resistor? What is meant by Diode-Connected load in MOSFET? Does it mean that MOSFET act like a diode connected with a load? Then why it is called as small signal ...
user411653
2 votes
1 answer
95 views
MOSFET Common-Source Stage with Resistive Load
If the \$V_\text{GS}\$ is constant, the graph, drain current is as shown. If \$V_\text{GS}\$ varies, the drain current is as shown My question is, what actually is a saturion region for MOSFET? Why ...
user411653
1 vote
0 answers
62 views
Output Noise of MOSFET with parallel current source
How can I calculate output noise voltage of the given circuit? Noise contribution of the M1 to output noise current: $$4kT\delta g_{m1}$$ Noise contribution of the RG to output noise current: $$4kTR_G[...
- 355
1 vote
1 answer
279 views
Analyzing \$g_m\$ vs \$V_{in}\$ for a common source config
I had this doubt while going through the book "Design of Analog CMOS Integrated Circuits" by B. Razavi, if we are to plot \$g_m\$ vs \$V_{in}\$ for the above circuit, then we have \$g_m\$ =0 ...
- 23
0 votes
2 answers
135 views
For a MOS transistor, why is the maximum voltage of it be \$V_{dd}-V_{ov}\$?
Razavi stated that the maximum output swing at X or Y is equal to \$V_{DD}β(V_{GS}βV_{TH})\$ as shown in the following picture, the second picture is the Fig.4.3 I don't understand why the equation ...
- 113
1 vote
0 answers
107 views
What are the values for A1 and A2 in the output voltage?
I got this question wrong, but I am not sure why it is wrong. The only part of the question I got right was the time constant, which is 8 seconds. I have attached the question as an image. The ...
- 65