Mosfet output resistance

1 Introduction. Currently, the silicon-based metal-oxide-semiconductor field-effect transistor (MOSFET) is the preferred semiconductor device in low to medium-powered high-frequency power processing applications [1-5].This kind of transistor represents one of the major sources of power losses and heating in such applications often requiring a …

MOSFET Output Resistance Recall that due to channel-length modulation, the MOSFET drain current is slightly dependent on v , and thus is more DS accurately described as: = K ( v GS − V ) ( 2 t 1 + λ v DS ) In order to determine the relationship between the small-signal voltage vgs and small-signal current i we can apply a 1. The CS ampli ers has in nite input impedance (draws no current at DC), and a moderately high output resistance (easier to match for maximum power transfer), and a high voltage gain (a desirable feature of an ampli- er). 2. Reducing R D reduces the output resistance of a CS ampli er, but unfortu-nately, the voltage gain is also reduced. We would like to show you a description here but the site won’t allow us.The second is its AC output resistance, which determines how much the output current varies with the voltage applied to the mirror. ... Figure 3: Gain-boosted current mirror with op-amp feedback to increase output resistance MOSFET version of gain-boosted current mirror; M 1 and M 2 are in active mode, while M 3 and M 4 are in ohmic mode and ...Creating a beautiful garden can be a rewarding experience, but it can also be frustrating when pests like deer come in and ruin your hard work. Deer can cause extensive damage to your plants, trees, and shrubs, leaving you with an unsightly...Current source characterized by high output resistance: roc. Significantly higher than amplifier with resistive supply. p-channel MOSFET: roc = 1/λIDp • Voltage gain: Avo = -gm (ro//roc). • Input resistance :Rin = ∞ • Output resistance: Rout = ro//roc. VB vs VBIAS vOUT VDD VSS iD iSUP RS signal source. Both these factors increase the collector or "output" current of the transistor with an increase in the collector voltage, but only the second is called Early effect. This increased …

1 Answer Sorted by: 3 @Keno Let's put it this way. When you operate your MOSFET in the saturation regime, as an amplifier, you use r0 in the small-signal analysis of the circuit. If you operate MOSFET as a switch (as in digital circuitry), and the switch is turned ON, you can use Ron, as long as the transistor is in the triode region.a relatively large Thevenin resistance and replicates the voltage at the output port, which has a low output resistance • Input signal is applied to the gate • Output is taken from the source • To first order, voltage gain ≈1 • Input resistance is high • Output resistance is low – Effective voltage buffer stage conditions, an equivalent circuit of the MOSFET gate is illustrated in Fig. 1, where the gate consists of an internal gate resistance (R g), and two input capacitors (C gs and C gd). With this simple equivalent circuit it is possible to obtain the output voltage response for a step gate voltage. The voltage VGS is the actual voltage at the gate ... Oct 5, 2022 · 0. 'Average Resistance' is not a well-formed parameter. Likely the OP means 'Output Impedance'. This is a useful value when the device is in saturation. This would be Δ𝑉/Δ𝐼 = (5-2.5)/ (10μ-9.3μ) = 3.6 MΩ. This could be considered the 'average' over that VDS range. The derivation of output impedance is unchanged from the JFET case. From the perspective of the load, the output impedance will be the drain biasing resistor, \(R_D\), in parallel with the internal impedance of the current source within the device model. \(R_D\) tends to be much lower than this, and thus, the output impedance can be ...Any power mosfet will do. For example if you pick IRF3205 you need find this datasheet information: The worst case scenario is shorted battery so all 4.2W will be on mosfet. You can look at the wattage like on "current source". So through your thermal circuit consisting of thermal resistance will flow 4.2W of power.Review: MOSFET Amplifier Design • A MOSFET amplifier circuit should be designed to 1. ensure that the MOSFET operates in the saturation region, 2. allowthe desired level of DC current to flow, and 3. couple to a small‐signal input source and to an output “load”. ÆProper “DC biasing” is required! MOSFET Small-Signal Model - Summary • Since gate is insulated from channel by gate-oxide input resistance of transistor is infinite. • Small-signal parameters are controlled by the Q-point. • For the same operating point, MOSFET has lower transconductance and an output resistance that is similar to the BJT. Transconductance: g m =2I D V GS

We saw previously, that the N-channel, Enhancement-mode MOSFET (e-MOSFET) operates using a positive input voltage and has an extremely high input resistance (almost infinite) making it possible to use the MOSFET as a switch when interfaced with nearly any logic gate or driver capable of producing a positive output. One of the most prominent specifications on datasheets for discrete MOSFETs is the drain-to-source on-state resistance, abbreviated as R DS(on). This R DS(on) idea seems so pleasantly simple: When the FET is in cutoff, the resistance between source and drain is extremely high—so high that we assume zero current flow.Oct 25, 2021 · For a NMOS, the transconductance gm is defined as id/vgs at a fixed VDS. However when we calculate the small signal gain of a common source amplifier, we use vds = -id x RD and then vds = -gm x vgs... Aug 17, 2020 · Because the gate of a MOSFET is effectively a capacitor, if you are switching at a high speed the gate will take some time to discharge and turn the transistor off. Suppose the MOSFET is a 2n7000 with an input capacitance of 50 pF and no Rg in the circuit. The impedance between the gate and ground could be, say, 50 MΩ. 1.4 Finite Output Resistance in Saturation When v DS is larger than V OV,2 the depletion region around the drain region grows in size. This is because the pnjunction near the drain is in reverse bias while the pnjunction near the source is in forward bias. So most of the excess voltage is dropped across the depletion region near the drain ...The cascode is a two-stage amplifier that consists of a common-emitter stage feeding into a common-base stage.. Compared to a single amplifier stage, this combination may have one or more of the following characteristics: higher input–output isolation, higher input impedance, high output impedance, higher bandwidth.. In modern circuits, the cascode …

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Shemafied. 183 2 7. If a mosfet is in cut-off, it is an open circuit. It can only be used as a resistor when it is conducting (not cut off). I'm just wondering if the op actually meant its triode region (ohmic region) because that would make more sense. Actually I did mean the cutoff-region. All is clear now. Jun 13, 2015 at 20:21.Low On-Resistance Solid State Relays Application Note 1046 Introduction The on-resistance is an important specification for a solid state relay that uses MOSFETs at its output. In general, a lower on-resistance rating will allow a higher contact current rating. The HSSR-8060 and HSSR-8400 are single-I then increased the width and length of the MOSFET, however the overall W/L ratio was still 20. One thing I noticed was the drain current decreased. ... This will cause the drain current to decrease by a factor of 2 and the transistor's output resistance ro = VA/IX increases by 4 times. The 4x increase comes from the 2 times increase in VA and ...winny. Dec 4, 2017 at 13:03. Input capacitance of the MOSFET is in the datasheet) and gate resistor will form a low-pass filter with a cut-off frequency of 1 2 iss) f C = 1 / ( 2 π R G i s s). This should be taken into account while selecting a series gate resistor. – Rohat Kılıç.zThe N channel MOSFET’s transconductance is: zAnd so the small signal model for this device will be a resistor with a resistance: ()( ) ()( )2 ()2 2 2 1 2 1 2 ... Approach: look at amplifier output resistance results … to see topologies that boost resistance Looks like the output impedance of a common-source amplifier with source degenerationMOSFET stands for "metal-oxide-semiconductor field-effect transistor": a name that fills one's mouth for sure.Let's learn what it means. Metal-oxide-semiconductor is a reference to the structure of the device. We will shortly analyze these in detail. Field-effect transistor means that a MOSFET is a device able to control an electric current using an …

The Early voltage ( VA) as seen in the output-characteristic plot of a BJT. The Early effect, named after its discoverer James M. Early, is the variation in the effective width of the base in a bipolar junction transistor (BJT) due to a variation in the applied base-to-collector voltage. A greater reverse bias across the collector–base ...The resistance value between the Drain and Source of a MOSFET during operation is called the ON Resistance. The smaller the ON Resistance, the lower the power loss during operation. Generally, increasing the chip size of the MOSFET reduces ON resistance. The ON resistance can be further reduced by introducing a trench electrode structure and/or ...Some of the best bands come without handles—so here's what to do to make them comfortable to use. Resistance bands are versatile, portable, and can provide heavy enough resistance for a variety of exercises, making them a valuable addition ...MOSFET Output Resistance Recall that due to channel-length modulation, the MOSFET drain current is slightly dependent on v , and thus is more DS accurately described as: = K ( v GS − V ) ( 2 t 1 + λ v DS ) In order to determine the relationship between the small-signal voltage vgs and small-signal current i we can apply a MOSFET stands for "metal-oxide-semiconductor field-effect transistor": a name that fills one's mouth for sure.Let's learn what it means. Metal-oxide-semiconductor is a reference to the structure of the device. We will shortly analyze these in detail. Field-effect transistor means that a MOSFET is a device able to control an electric current using an …Low On-Resistance Solid State Relays Application Note 1046 Introduction The on-resistance is an important specification for a solid state relay that uses MOSFETs at its output. In general, a lower on-resistance rating will allow a higher contact current rating. The HSSR-8060 and HSSR-8400 are single-The cascode is a two-stage amplifier that consists of a common-emitter stage feeding into a common-base stage. [1] [2] Compared to a single amplifier stage, this combination may have one or more of the following characteristics: higher input–output isolation, higher input impedance, high output impedance, higher bandwidth .I then increased the width and length of the MOSFET, however the overall W/L ratio was still 20. One thing I noticed was the drain current decreased. ... This will cause the drain current to decrease by a factor of 2 and the transistor's output resistance ro = VA/IX increases by 4 times. The 4x increase comes from the 2 times increase in VA and ...For a MOSFET operating in saturation region the channel length modulation effect causes a decrease in output resistance. The drain characteristics becomes less flat. Ideally drain characteristics is flat which implies infinite impedance. Due to channel length modulation early voltage is introduced which gives finite output resistance.

Abstract: One of the MOSFET compact modeling challenges is a correct account of the finite output resistance in saturation due to different short channel effects. Previously, we proposed a new “improved” smoothing function that ensures a monotonic increase in output resistance from the minimum value at the beginning of the triode …

Since a MOSFET is similar to a BJT with rπ infinite, this makes intuitive sense. Note also that a resistor at the gate of a MOSFET would not affect the input resistance of a common-gate amplifier like the base resistance affects …10/19/2004 Drain Output Resistance.doc 5/5 Jim Stiles The Univ. of Kansas Dept. of EECS Finally, there are three important things to remember about channel-length modulation: * The values λ and V A are MOSFET device parameters, but drain output resistance r o is not (r o is dependent on I D!). * Often, we “neglect the effect of channel-length A MOSFET is a four-terminal device having source (S), gate (G), drain (D) and body (B) terminals. In general, The body of the MOSFET is in connection with the source terminal thus forming a three-terminal device such as a field-effect transistor. MOSFET is generally considered as a transistor and employed in both the analog and digital circuits.Electrical channel length decreases a bit with further increase of Vd after saturation, causing the drain current to increase slightly. In circuits, this will cause some output conductance, or a finite amount of output resistance, limiting the so-called open-loop voltage gain of a transistor amplifier.0. 'Average Resistance' is not a well-formed parameter. Likely the OP means 'Output Impedance'. This is a useful value when the device is in saturation. This would be Δ𝑉/Δ𝐼 = (5-2.5)/ (10μ-9.3μ) = 3.6 MΩ. This could be …In Razabi's Design of Analog CMOS Integrated Circuits textbook, when he calculates the output resistance of a common source stage with source degeneration, He uses the small-signal model below: My . ... Small-signal output resistance of MOS common-source stage with source degeneration. 1.winny. Dec 4, 2017 at 13:03. Input capacitance of the MOSFET is in the datasheet) and gate resistor will form a low-pass filter with a cut-off frequency of 1 2 iss) f C = 1 / ( 2 π R G i s s). This should be taken into account while selecting a series gate resistor. – Rohat Kılıç.Oct 10, 2011 · An ideal current source has an infinite output impedance. This means that the current "just flows" regardless of how large or small the load resistance is and the voltage adjusts accordingly. For example, if you had an ideal 3 amp current source, then if you loaded it with 10 ohms the output voltage would be V = IR = 3A x 10 = 30V. Creating a wildlife-friendly garden is a great way to attract birds, butterflies, and other animals to your outdoor space. While this can be a rewarding experience, it can also be challenging if you live in an area with a large deer populat...Sep 1, 2015 · The resistance r 0 is a parameter of the mosfet which does not depend on small signal or any other signal. Whereas, small signal resistance is the resistance you see at the output on applying a small signal input, that is. and the output resistance is. Share. Cite.

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• Input resistance is zero • Output resistance is infinity Also, the characteristic V MIN applies not only to the output but also the input. • V MIN(in) is the range of v in over which the input resistance is not small • V MIN(out) is the range of v out over which the output resistance is not large Graphically: Therefore, R out, R in, V ...https://www.patreon.com/edmundsjIf you want to see more of these videos, or would like to say thanks for this one, the best way you can do that is by becomin... Equation (1) models MOSFET IV in so called triode or nonsaturation mode, i.e. before channel pinch-off or carrier velocity saturation. We will be mostly concerned about MOSFET operation in saturation mode (Equation (2)). One more thing has to be mentioned – finite output resistance of the MOSFET in saturation, i.e. dependenceThis will be the equivalent of a non ideal current source in which there is some apparent and non-infinite output resistance. MOS = "Metal Oxide Semiconductor" is a form of semiconductor manufacturing technology. CMOS ICs use it and MOSFETs. Current sources and current mirrors may be made using it BUT the two are independent.Abstract: One of the MOSFET compact modeling challenges is a correct account of the finite output resistance in saturation due to different short channel effects. . Previously, we proposed a new “improved” smoothing function that ensures a monotonic increase in output resistance from the minimum value at the beginning of the triode regime to the maximum value ata relatively large Thevenin resistance and replicates the voltage at the output port, which has a low output resistance • Input signal is applied to the gate • Output is taken from the source • To first order, voltage gain ≈1 • Input resistance is high • Output resistance is low – Effective voltage buffer stageAn ideal current source has an infinite output impedance. This means that the current "just flows" regardless of how large or small the load resistance is and the voltage adjusts accordingly. For example, if you had an ideal 3 amp current source, then if you loaded it with 10 ohms the output voltage would be V = IR = 3A x 10 = 30V.May 22, 2022 · Figure 13.3.1: Common drain (source follower) prototype. As is usual, the input signal is applied to the gate terminal and the output is taken from the source. Because the output is at the source, biasing schemes that have the source terminal grounded, such as zero bias and voltage divider bias, cannot be used. MOSFET - is an acronym for Metal Oxide Semiconductor Field Effect Transistor and it is the key component in high frequency, high efficiency switching applications across the electronics industry. It might be surprising, but FET technology was invented in 1930, some 20 years before the bipolar transistor. ….

An ideal current source will have an infinite output impedance. You could connect a resistor in parallel with the current source but that resistor would need to have an infinite value R = infinite ohms because if the resistor value was any lower than infinite, current would flow through it and the current source (including resistor) would not be ideal anymore.a relatively large Thevenin resistance and replicates the voltage at the output port, which has a low output resistance • Input signal is applied to the gate • Output is taken from the source • To first order, voltage gain ≈1 • Input resistance is high • Output resistance is low – Effective voltage buffer stage4. Input and output resistance calculations for amplification purposes plays into the input and output impedance of the circuit. The input and output impedance gives information on the bandwidth on both input and output of the circuit (i.e. how fast capacitances can be charged and discharged) as well as the impedance needed to drive the circuit ...path: the internal resistance of the gate driver, external gate resistance, and internal gate resistance of the MOSFET or IGBT. RGATE is the only component that tunes the gate drive waveform. Figure 2. Switching Theory Figure 2 shows the parasitic inductances and their effect on the gate drive waveform created by long trace length and poor PCB ...One of such major parasitic resistance present in the MOSFET structure is due to contact resistances. Recall that the 3D structure used at the very start of the previous post contained metal contacts over the drain and source. These are called “Metal Contacts”, and they are used to connect the MOSFET terminals to the external circuits.The output of the cascode amplifier is measured at the drain terminal of the common gate stage (M2). For a time being here, the load is not shown. But the load could be a passive resistive load or it could be an active load like a resistor. The Cascode amplifier provides high intrinsic gain, high output impedance and large bandwidth.A Form C relay output is a single-pole double-throw, or SPDT, relay that breaks the connection with one throw before making contact with the other, a process known as “break before make.” Relays are classified into forms, the most common of...The Actively Loaded MOSFET Differential Pair: Output Resistance; The Diff Pair with Output Resistance. In the previous article, we discussed MOSFET small-signal output resistance (r o): why it exists, how it affects an amplifier circuit, and how to calculate it. Now we will use this newfound expertise to examine the gain of the actively loaded ... Mosfet output resistance, The output of the cascode amplifier is measured at the drain terminal of the common gate stage (M2). For a time being here, the load is not shown. But the load could be a passive resistive load or it could be an active load like a resistor. The Cascode amplifier provides high intrinsic gain, high output impedance and large bandwidth., • A well controlled output voltage • Output voltage does not depend on current drawn from source ⇒Low Thevenin Resistance Consider a MOSFET connected in “diode configuration” ()2 ()2 D 2 n ox GS Tn 2 n ox DS Tn C V V L W C V V L W I = µ − = µ − Beyond the threshold voltage, the MOSFET looks like a “diode” with quadratic I-V ... , 2. Looking into the drain, the small-signal resistance is. r i d = r o = λ − 1 + V D S I D. if the source is at AC common (common-source configuration). If the AC resistance from source to common is R t s ≠ 0, the small-signal resistance looking into the drain is. r i d = r o ( 1 + R t s r s) + R t s. where. r s = 1 g m., The resistance value between the Drain and Source of a MOSFET during operation is called the ON Resistance. The smaller the ON Resistance, the lower the power loss during operation. Generally, increasing the chip size of the MOSFET reduces ON resistance. The ON resistance can be further reduced by introducing a trench electrode structure and/or ..., – The transistor open circuit does have a finite output impedance, so the ... with a CS amplifier to improve its output resistance: Cascode. 22. Page 20 ..., One of such major parasitic resistance present in the MOSFET structure is due to contact resistances. Recall that the 3D structure used at the very start of the previous post contained metal contacts over the drain and source. These are called “Metal Contacts”, and they are used to connect the MOSFET terminals to the external circuits., This is when we need to determine the MOSFET output resistance r o2. The small-signal drain current for the PMOS transistor is. And v gs2 = 0, thus. The hybrid-pi model for the small-signal PMOS is. Since v gs2 = 0, the small-signal model will be. We can simplify it into, Figure 3 shows a MOSFET common-source amplifier with an active load. Figure 4 shows the corresponding small-signal circuit when a load resistor R L is added at the output node and a Thévenin driver of applied voltage V A and …, The cascode transistor works like an impedance converter. It conducts the input current (the signal current) (I out = I in). The AC resistance of the source of T casc, that we also call the input resistance (r in) of the cascode, is small. The resistance at the drain of T casc (the output resistance r out) is large. T casc I in Out I out In ... , Calculate ix i x and calculate vx/ix i.e. rd1 r d 1, which should be trivial. For that circuit, with diode-tied gate-drain connection, the dynamic resistance will be the transconductance. For long-channel FETS, the transconductance is just the derivative of Idd (Vgate), or. To derive this maths, write the triode-region small-signal iout (vgate ..., conditions, an equivalent circuit of the MOSFET gate is illustrated in Fig. 1, where the gate consists of an internal gate resistance (R g), and two input capacitors (C gs and C gd). With this simple equivalent circuit it is possible to obtain the output voltage response for a step gate voltage. The voltage VGS is the actual voltage at the gate ..., MOSFET input opamps may have input resistances as high as 10 13 13 Ω. Resistance determines the amount of current that flows when a certain voltage is applied. High resistace means less current (at the same Voltage). Ohms law, google if you don't understand that yet. The input resistance is the equivalent resistance of the input (in a FET's ..., MOSFET Characteristics (VI And Output Characteristics) September 19, 2021 by Electrical4U. MOSFETs are tri-terminal, unipolar, voltage-controlled, high input impedance devices which form an integral part of vast variety of electronic circuits. These devices can be classified into two types viz., depletion-type and enhancement-type, …, 4/25/2011 MOSFET Output Resistance 1/2 Jim Stiles The Univ. of Kansas Dept. of EECS MOSFET Output Resistance Recall that due to channel-length modulation, the …, A MOSFET can easily be used as a variable resistor. You have to consider few important parameters before using as a variable resistor. Main things are. The minimum resistance you need and the \$ R_{DS(on)} \$ of the MOSFET you have chosen. The MOSFET's behavior in the linear region though it is similar for almost all the MOSFETs., The amount of resistance between the drain and source when the MOSFET is active. Knowing the Vgs-threshold is critical because many high power MOSFETs have a Vgs in the range of 10 to 15 volts. Such a high threshold means you need a driver circuit when used with 3v3 or 5 volt embedded controllers like an Arduino, Raspberry Pi, or …, The input resistance is large due to the inputs being at the gate terminals of the MOSFET differential pair. Notice that the output resistance is also large. 4 â è ç 4 6|| 4 : The gain-bandwidth product (GBW) is given approximately by: ) $ 9 L C à 5, % Å An improvement of the differential amplifier in Figure 7-3 is to use self-biased loads., When we have resistive loads in a single stage amplifier, they convert the signal current change into voltage variation. Higher the value of load, more will be the conversion and hence the gain. In MOSFETs, since it is not necessary for the output impedance to be less, higher gain can be obtained by increasing the RD** (physical resistance ..., MOSFET stands for "metal-oxide-semiconductor field-effect transistor": a name that fills one's mouth for sure.Let's learn what it means. Metal-oxide-semiconductor is a reference to the structure of the device. We will shortly analyze these in detail. Field-effect transistor means that a MOSFET is a device able to control an electric current using an …, MOSFET Small-Signal Model - Summary • Since gate is insulated from channel by gate-oxide input resistance of transistor is infinite. • Small-signal parameters are controlled by the Q-point. • For the same operating point, MOSFET has lower transconductance and an output resistance that is similar to the BJT. Transconductance: g m =2I D V GS, Accurate MOSFET Modeling Approach with Equivalent Series Resistance of Output Capacitance for Simulating Turn-OFF Oscillation. Abstract: High-speed switching of …, a relatively large Thevenin resistance and replicates the voltage at the output port, which has a low output resistance • Input signal is applied to the gate • Output is taken from the source • To first order, voltage gain ≈1 • Input resistance is high • Output resistance is low – Effective voltage buffer stage, The FET package itself also has some resistance (and inductance). Even the FETs within the gate driver IC have a resistance. When a gate driver "turns on" you are essentially charging this gate to source cap from your gate driver VCC through the gate driver top FET resistance, the gate resistor on your board and the internal gate …, 2. Have a look at the picture below. The green lines show the drain current of a transistor without channel length modulation (resistance is inifinite) and the black lines are for a transistor with channel length modulation. The current is obviously not zero, but the change of current (and therefore the slope of the curve) in the saturation ..., • Input resistance is zero • Output resistance is infinity Also, the characteristic V MIN applies not only to the output but also the input. • V MIN(in) is the range of v in over which the input resistance is not small • V MIN(out) is the range of v out over which the output resistance is not large Graphically: Therefore, R out, R in, V ... , Channel length modulation ( CLM) is an effect in field effect transistors, a shortening of the length of the inverted channel region with increase in drain bias for large drain biases. The result of CLM is an increase in current with drain bias and a reduction of output resistance. It is one of several short-channel effects in MOSFET scaling., The derivation of output impedance is unchanged from the JFET case. From the perspective of the load, the output impedance will be the drain biasing resistor, \(R_D\), in parallel with the internal impedance of the current source within the device model. \(R_D\) tends to be much lower than this, and thus, the output impedance can be ..., 1.3 Output/Input Resistance of the Diode-Connected Transistor Luckily the analysis is quick and easy in this case. We take the output to be the gate or base of the transistor (the same node as the source/collector). Fig. 4 shows the setup for the output impedance (same as the input). By observation: R out =R s =1=g m kr o ˇ1=g m (3) , Common Source MOSFET with source degenerations looks like this I am a bit confused about different input and output resistance statements (provided by different sources). Some of them say that applying Rs to circuit DOES NOT change input and output resistances even a bit (which I hardly believe). , MOSFET Small-Signal Model - Summary • Since gate is insulated from channel by gate-oxide input resistance of transistor is infinite. • Small-signal parameters are controlled by the Q-point. • For the same operating point, MOSFET has lower transconductance and an output resistance that is similar to the BJT. Transconductance: g m =2I D V GS , When we have resistive loads in a single stage amplifier, they convert the signal current change into voltage variation. Higher the value of load, more will be the conversion and hence the gain. In MOSFETs, since it is not necessary for the output impedance to be less, higher gain can be obtained by increasing the RD** (physical resistance ... , 1.4 Finite Output Resistance in Saturation When v DS is larger than V OV,2 the depletion region around the drain region grows in size. This is because the pnjunction near the drain is in reverse bias while the pnjunction near the source is in forward bias. So most of the excess voltage is dropped across the depletion region near the drain ..., ron - this is the large-signal MOSFET channel resistance. This parameter is derived by the partial derivative of the current operating point versus a point where Vds = 0 and Ids = 0. Even if trivial, worth noting here that we calculate ron by: ron = [∂vds ∂ids]Vgs=const r o n = [ ∂ v d s ∂ i d s] V g s = const.