Questions tagged [common-gate]

One of the three basic FET amplifier topologies. The FET's source terminal is the input, the drain is the output, and the gate is connected to ground (or "common", hence the name). The analogous BJT circuit is the common base. Use this tag along with the "mosfet" and "transistors" tags for questions about common gate circuits.

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PMOS configured in common gate

This is an NMOS configured in common gate: I am trying to understand what a PMOS configured in common gate would look like. Would Vin and Vout be reversed in this case? So, would VDD be connected to ...
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Where to apply input source to common gate configuration

I have learned from my teacher that the input of the common gate is applied at the source pin and the output voltage is probed from the drain pin, why not vice versa? Can I do that?
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Differences between EPROM and EEPROM

I found one valuable Utmel blog which explains the three things: The internal chip can be erased by irradiating ultraviolet rays through the hole. The EPROM eraser is needed to complete the chip ...
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Convert boolean expression to nand gate only. X = A'B'C+AB'C'+A'B'

I have already made a diagram. However, it won't match the truth table that I have made, which I got from the logic converter in multisim. Could you please help me out with where did I go wrong? Is it ...
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Thevenin Equivalent of Common-Gate Amplifier

I'm having some difficulty understanding how Razavi determined \$V_{\text{in, eq}}\$. My understanding was that the small-signal model allows us to model the PMOS device as a constant current source (\...
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Common Gate Transimpedance Amplifier Transfer Function

I am trying to find the transfer function of the common gate transimpedance amplifier. The transfer function that I got is different than the one at the original publication even though it leads to ...
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Small-signal voltage gain of P-type common-gate circuit

Given the following p-type common-gate circuit, I'd like to try and calculate the voltage gain \$A_v=V_o/V_i\$. Given the following information: \$V^+=5V\$, \$V^-=-5V\$,\$V_{TP}=-0.8V\$,\$\lambda=0\$, ...
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Why would a common Gate MOSFET (instead of a resistor) reduce noise in a TIA?

simulate this circuit – Schematic created using CircuitLab I am reading a paper on TIA for optical receivers. On one of the improvements regarding the noise the writers replace the feedback ...
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How does the current pass through FET when its gate is unbiased/grounded in AC analysis?

My first question is how does the drain voltage increase V(drain) when the source voltage V(source) is increased for the below common gate FET: And secondly and most importantly in AC analysis they ...
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Find gain of this common-gate

I have a large circuit involving feedback as follows I am trying to find the closed-loop gain of this. Before I can do that, I need to find the open-loop gain. Thus, removing the feedback loop, M2 ...
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What happens when the DC supply of this common gate amplifier is switched off?

The Vin in this case is a 200 mV peak to peak sine wave signal. What happens to the gain of the amplifier when the DC supply of 10V is switched off?
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How does a common gate MOSFET turn on if the gate is grounded? [closed]

For a NMOS to turn on the Gate to Source potential diff has to be greater than the threshold voltage. But if the gate is grounded like shown in M1 below how could the MOSFET ever be turned ON (or how ...
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determine the cutoff frequency of an nMOS in common gate with gate resistance

I have to determine the upper cutoff frequency of this circuit. I absolutely mustn't use the Laplace domain because it's too time consuming so not compatible with the time I have at the exam. A rapid ...
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Negative Gain and in a common gate FET amplifier

We conducted an experiment involving frequency response in common gate FET amplifier. The results at different frequencies from 10 Hz to 1 MHz are obtained and we got a negative result in the first ...
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Biasing arrangement - common gate amplifier

I'm just really confused at the moment with biasing all these different MOSFET amplifier arrangements. Here is one, This is a common-gate amplifier and I am told that it is biased by a constant ...
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Calculate the upper cutoff frequency of a common gate

JFET: I am trying to calculate the upper cut-off frequency of this circuit. Gain gave me 5, as it did in the teacher's solutions. But I'm applying the expression to the condensers and it's giving me ...
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Transistor noise figure in common base / common gate configuration

My question regards BJT and JFET devices. Noise figures for transistors are usually given along with specific signal source resistances and collector / drain currents. How can one apply these ...
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Common gate with low input impedance

This is from my textbook talking about the advantages of a common gate amplifier. The author says that the common-gate stage is usually superior to that of the common-source stage for two reasons. ...
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Common Gate For Power MOSFET

The common base configuration has been well documented for the BJT. Small signal analysis shows better high frequency capability than a common emitter for the same transistor. I have seen common gate ...
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Common Emitter not amplifying

I am trying to make a 27 MHz carrier wave transmitter from a crystal oscillator and a secondary amplifier. This is the complete circuit: simulate this circuit – Schematic created using ...
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Common Gate Level Shifter

I am in the need for a high-side load switch and came up with the following schematic. High-Side voltage levels and current vary between 5-12 V / 2 A max. The high-side PMOS (SI5509DC) is rated for 20 ...
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Common gate amplifier with load connected to negative DC bias

What's the difference between the following two circuits? Note that the capacitors are DC blocking, and the FET is on. I understand that usually, the load is connected to ground. But what would ...
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MOSFET in high frequency applications

I've heard that MOSFETs for high frequency circuits are generally configured as common gate. Can anyone explain why? Could this be related with the internal MOS capacity?
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