I have simulated the circuit with the following values. VDD = 1.8V, Vin is a sine wave with fin = 450MHz, pin = -5dBm, L1 = 12.5nH, C1 = 10pF, RL=50 ohm. I also gave a biasing dc voltage at the gate of MOSFET as 1V. I got the following graph after simulation.    The red graph is the input sine wave. The yellow graph is the current at the drain of MOSFET and the green one is the voltage at the drain of MOSFET. But I am not exactly getting what the graph means or how to interpret it? If I am using it as a power amplifier how can I improve the output values of voltage and currents?
123059
In the power amplifier circuit shown if the input is an RF sine wave, with VDD=1.8V and Vgs = 1V, what will be the waveform at the drain of the MOSFET - sine or square wave? Is it possible to get a sine wave at the drain?
25500
A lot of times in circuits I see a resistor placed in series in a signal line and sometimes even in series with an MCU's VDD line. Is the intention of this to smooth out noise in the line? How is this different from using a small cap, like a .1µF to do the same thing?
111776
I am working on the lab which is allowed to ask other people for hints.    In the image, program called "Audacity" is used to capture that waveform.  Question 1     In the image it says, "The peak-to-peak span of the signal is about 2.0 V"   It says its span range is 2.0 V, but I think that it spans from around -0.2 (lowest point in the wavefore picture) to +0.8 (highest point in the wavefore picture) according to picture. But why this description says it is 2.0 V?  Question 2     In the image it says, "the graph below can show a range of about 4 volts top-to-bottom"   Similarly, I think total range of top-to-bottom in the image is from -1.0 to +1.0, which I think 2V in total. But why this description says it is 4 volts?
110841
There is a circuit shown below where we have a sub-circuit I marked in red. I know that it is a source follower with the AC behavior shown below. As you can see the circuit has DC voltage input only. What is the DC behavior of the part I marked with the red arrow?
15401
I think, it is time I understand working principle of MOSFET transistors...    Suppose that;   I want to switch voltage on a resistive load by a MOSFET transistor.   Any control signal between -500V and +500V can be easily generated.   The transistor models in the picture are not important, they can be of any other appropriate model as well.   Question #1 Which of the driving techniques are feasible? I mean, which of these four circuits would work with correctly applied control signals?  Question #2 What is the range of the voltage level of the control signals (CS1, CS2, CS3, CS4) that loads and unloads the resistor? (I understand that exact boundaries of on and off states must be calculated individually. But I'm asking for approximate values to understand the working principle. Please give statements like "In circuit (2), the transistor turns on when CS2 is below 397V and turns off when above 397V.".)
585
I realize connecting two different voltage sources in parallel is a contradiction (in an ideal circuit). But if I were to connect this in practice and measure the voltage across points A and B, what value of voltage would it show? And how much current would be sunk by the 5V battery? (Non ideal conditions)
123742
Here is what I have understood. Please correct me if I'm wrong.  The depth of induced channel depends on the voltage V. Since the voltage across the gate and  the path along the channel decreases from Vgs at the source to drain end to drain end, the channel is not uniform an is tapered. If the applied voltage Vds is increased to some value which causes the voltage between gate and drain end to be lesser than the threshold voltage, the channel is said to be pinched off.  If the channel is pinched off, how does the drain current flow? It's given in the book that the MOSFET enters saturation region and will have a constant value of drain current. But I don't understand how does the current flow when the channel no longer exists at the drain end.
38517
Could anyone help to analyze the circuit? I think block A should be a OP comparator. How about the other blocks function? Thanks a lot! The V1 is a adjust voltage source from a DAC between 4V to -4V
76886
What would be the calculation for the output voltage of this full wave bridge rectifier?    Thank you.
25415
I am trying to build a DC-DC Buck-Boost Converter using  basic schematic and an Arduino with the analogWrite() function as my PWM generator. I only want to step up 2.4-3V to ~5V. If it's just the capacitor and no load, the converter works so good that I have to switch it off after a few seconds since the voltage I measure on my capacitor is exceeding the capacitor limit. However, when I connect any load to the capacitor(for example a motor or a resistor) my voltage drops to a really low value(0.1-2v) and stays that way no matter what frequency PWM signal I send to the transistor using Arduino. I really tried but couldn't find the cause of the problem. Is it because I have two grounds, the battery pack one and the Arduino one? Is it because of the inductor(I tried using a smaller, 45uH, torroidal one but couldn't get any better results)? So what am I doing wrong?   I only expect to draw 500mA of current at 5 volts at the output side, and according to  calculator my inductor and transistor should be fine.  Components: 100uF 35V electrolytic capacitor, 200uH inductor, BYW29 rectifier diode, TIP 120 power transistor, 1k resistor    A schematic of the circuit or at least how it is supposed to look. Maybe I miswired something? The resistor is to represent  the load, the value doesn't matter since my problem persists at any value but the multimeters "infinite" resistance.   This is how my circuit looks   I used one coil of an old transformer as my inductor    However I also tried this inductor
2772
This DAC has an output range of 1-3 volts. Here's the datasheet:    I'm getting pulses with different amplitudes, frequencies, duty cycles and widths varying from 0.2 ms to 2 s from the DAC. I want an output range of 0-4 volts instead (Vcc=5v). I tried a high-pass RC filter, and then amplified it with an op-amp, but the output doesn't look like a pulse anymore. Also, I tried the circuit suggested in the datasheet (page 8) with no luck. I'm not sure what values I should assign to this circuit, since I don't understand how it functions. How should I go about this?
116085
I want to convert the  output voltage of an ECG (-5 to +5) to 0 - +5 volt for ADC. Should i use Op amp ? What is my problem in this picture? I simulated it in Proteus ... but when input voltage is higher than 4 V or lower than -4 V Vout gives an unexpected value.   Below is another simulink that have same problem ...    My idea to make this level of voltage is (Vin +10)/2 that give the range 0-5 V.
42748
I am struggling to understand two things about this circuit.  1) when input and output terminals are open circuit, why is this assumed to be in active mode?  2)What range can the quiescent output voltage of the amplifier be in?  Now I know that active mode you need EBJ to be forward bias and CBJ to be reverse bias but how would this apply in this scenario?  I understand what quiescent voltage is but I am struggling to apply his here with the input and output terminals. I would appreciate any help.  Many thanks.
71646
So can anyone explain me how the collector voltage(V (output)) will vary with variation in base current with respect to the following figure?         &ndash; Schematic created using
49032
For an ideal OpAmp the voltages at the inputs are said to be of equal value and the currents 0, however, for we also know that $$V_\text{out}=A(V_p-V_n)$$ but if the voltages are the same the output should always be 0!  I know that what I'm saying is wrong, but I don't know where the loophole is, and I can't find it anywhere.
69407
&ndash; Schematic created using  There is also the resistance of the Mosfet which is equal to 0.25(Ohm) I just didn't know how to add it to the circuit. We're gonna call it Rdson. First question says: Calculate Ids that passes through the transistor. Vcc - rIds - Rdson x Ids = 0 Ids = 12/ (0.25 + 1.25) = 8 A Second question says: Calculate VDS(max) Vds = Ids(r + Rdson) = 8(1.5) = 12v That's what I don't understand. Why the book included r in calculating VDS? Isn't it supposed to be: Vds = Ids x r Did the book make a mistake here? Also, is VDS(max) the same as normal VDS? My problem: How VDS(max) is calculated in this circuit? Is the way the book solved it correct?
86608
I've been trying to make a current source, and have finally gotten my hands on some  which should be an 'unlimited cap drive' op-amp. The problem is, it is still oscillating. This is the schematic and PCB layout:   I have tried to route the ground inside the loop area, close to the 5V connection for the opamp, so I could place the bypass capacitors as close as possible. Although the bigger 10uF cap has one of its legs at the groundplane (forgot to include this cap in the schematic picture.) This is what it looks like when I probe the gate of the MOSFET:  It's all over the place. I tried adding a 10uF capacitor across the DUT, so from VDD to ground. This removed a lot of the wierd noise and made it look almost like a sinewave:  I've tried with and without the gate resistor R1, it didn't seem to make any difference. What is going on? Any clues on why this just doesn't work? EDIT: Solved it! With the help from @Andyaka below, I used his solution of inserting a BJT emitter follower in between the op-amp and the MOSFET, together with an integrator and got some great results! Final circuit:  The simulations can be seen here:  The gain/phase bode plots I made on the PCB:  Bandwidth of approximately 350kHz! Very pleased.