All Questions
Tagged with diff-amp or differential-amplifier
333 questions
2
votes
2
answers
31
views
How to Get Negative Voltage with Virtual Ground for Differential OpAmp? (One power supply)
I am reading about working with virtual ground and generating negative voltage. I am trying to power a differential op amp circuit, and I expect some of these differences to result in a Vout that is ...
- 21
1
vote
3
answers
103
views
How to stabilise the BJT diff. pair feedback loop?
I need to remove the oscillation of feedback loop while fast response is maintained.
I have no problem to avoid the oscillation if 47 nF cap is placed across output but since I want to feed the input ...
- 2,881
-3
votes
0
answers
76
views
I want to increase bandwidth of Op Amp that I made with BJT [closed]
What should I do? I cannot change BJT can only add some resistor or capacitors. I want to have more than 3kHz of BW and 10000 of open loop gain.
- 11
2
votes
0
answers
46
views
Autozero OPAMP design
I am trying to design an autozero ping-pong amplifier for a school project. I searched in books and on the internet for architectures, but all of them are so different that I don t know which is best.
...
1
vote
0
answers
79
views
Telescopic cascode amplifier design
I was following a tutorial from youtube and learning about double ended telescopic cascode 2 stage amplifiers. I was curious to know how to modify this circuit to get single ended zwo stage telescopic ...
- 53
1
vote
0
answers
87
views
Frequency response of 5 transistor OTA
I need to calculate the open loop zeros and poles for this system.
What I tried is at some node between Gm2 and Gm1 block there will be one pole and value of effective capacitor is the capacitor which ...
- 53
-1
votes
0
answers
82
views
Designing a single ended Operational Transconductance
I am working on designing a single-ended Operational Transconductance Amplifier (OTA) with the following specifications in 180nm technology using LTspice:
DC Gain: > 65 dB
Unity Gain Bandwidth: >...
0
votes
1
answer
22
views
Do you get common mode noise at the receiver if the receiver side has common impedance to ground, but not the transmitter side?
Balanced lines are when two conductors have a common impedance along the entire length of the conductors. This helps ensure that noise induces equal voltage spikes as seen by the differential receiver ...
- 2,086
2
votes
0
answers
30
views
Window current detection through a current sense differential amplifier and a comparator
I'd like to implement a circuit to detect the over-current through a grounded load. The limits for that current are either 3mA DC current or -3mA and 3mA in case of bipolar AC current. I want to ...
- 97
-2
votes
2
answers
79
views
Replace a diff-amp with an in-amp in a voltage-controlled current source using LTspice
I am simulating the following voltage-controlled current source using LTspice. This design works for the application where it is going to be applied. However, the output current is not completely ...
- 97
0
votes
4
answers
79
views
Purpose of Additional Resistor in a Wheatstone Bridge and Differential Amplifier Circuit with Platinum RTD (R9)
The combination of a Wheatstone bridge and a differential amplifier circuit is quite common. However, I encountered a circuit (shown in the diagram) with a unique configuration. In this design, an ...
- 11
1
vote
2
answers
94
views
Differential Amplifier: Common-mode rejection
From Fundamentals of Microelectronics, Behzad Razavi
For this circuit:
The following equations are given:
From which it concludes
Now, let us vary VCM in Fig. 10.7 by a small amount and determine ...
1
vote
1
answer
34
views
Convert MBF Band pass to differential band-pass
The problem
I need to design a differential to single-end band-pass filter & amplifier before an ADC (sampling at 8kHz) :
DC-blocking
0dB at 60Hz
10dB (ideally 20dB) for frequency above 120Hz
-...
- 11
1
vote
4
answers
191
views
Understanding the Behavior of a Potentiometer in Gain Control for a Differential Amplifier
I’m studying a design of a differential input circuit where a potentiometer in the feedback loop controls the gain. I’m using the general gain formula for a differential operational amplifier. However,...
- 67
4
votes
3
answers
395
views
How can I use an op-amp in differential configuration to measure voltage across a MOSFET?
I want to use an opamp in a differential configuration to measure the voltage at the drain and source terminals of a mosfet.
The mosfet will have a maximum of 400Vds across it.
I cannot find an opamp ...
- 190
3
votes
2
answers
224
views
Subtract 2 voltages and amplify using 1 op-amp
I am designing circuit that senses voltage of multiple batteries in series. The circuits in the picture uses 2 LM358 op-amps, and does the operation((Bat3+ - Bat2+)-2.5)*20/6.8, to fully use the ADC ...
- 31
0
votes
3
answers
137
views
If the inverting and non inverting terminal of an op-amp are at the same voltage then how does a differential amplifier work? [duplicate]
I'm just starting off studying op-amps, I had a question, if V+ and V- are approximately equal, then Vd is approx. 0. Then, in a differential amplifier, if I give the inputs as, say, 5V and 2V, I ...
- 11
0
votes
1
answer
48
views
How to drive single or multiple pvdf film type piezo actuators
this is going to be a little long but I wanted to include as much detail as possible in my question. There is a TLDR at the end.
I am part of a design team focused on making a vibration and audio ...
0
votes
2
answers
177
views
Does the MOSFET go into the linear region when the op-amp goes into saturation?
Consider the following two stage differential amplifier:
Let's say the input differential voltage is high enough to put the amplifier into saturation region. In that case MOSFET M6 will be pushed to ...
- 180
2
votes
1
answer
132
views
Single ended to differential conversion and back using op-amps
I have a single ended signal that I want to convert to a differential signal.
The single ended signal is a 0V - 1.8V rectified signal with a frequency of 16Mhz. To convert the signal a LMH6552 fully ...
- 21
2
votes
1
answer
102
views
Confusion with two types of differential signal coupling
I'm having difficulty to articulate the question. But perhaps I might get close to it by an example.
I know that in differential signaling, both the signal and the receiving amplifier can be in ...
- 4,385
0
votes
0
answers
51
views
MOS differential amplifier output swing
Why is the maximum output voltage swing of a MOS differential amplifier 2Vdd-4Vdsat? I understand that the voltage swing of a MOS CS amplifier, but I don't know how they got that the voltage swing of ...
1
vote
0
answers
92
views
Working of differential pair using MOSFETs
I am currently learning about differential pair using MOSFET from this course. In this particular lecture, the teacher says that to have a differential pair we need to apply the second signal v2 at ...
- 180
1
vote
1
answer
54
views
Common-mode choke in ECG circuit
I'm designing a PCB for single lead ECG measurement and I ran across this TI reference design that contains a common-mode choke (P/N Murata DLW31SN900SQ2L). What's strange is that I can't find any ...
- 137
0
votes
0
answers
39
views
AD8232/AD8233 not working for sEMG
I am working on an sEMG circuit using the AD8232 and cannot figure out what is going wrong, the circuit isn't outputting the correct signal when connected to the forearm. I am using the 3 lead ...
- 11
1
vote
0
answers
58
views
Is it safe to flip the use of resistor pins of the INA106 differential amplifier to turns its gain from 10 into 0.1?
I'd like to have differential amplifier with gain of 0.1 without having to put any external resistor. Most of them in the datasheet states the use of gain of 1 or more and rarely specify the use of ...
- 844
0
votes
2
answers
102
views
Differential amplifier Q point
I'm looking for a way to solve the Q point of this amplifier
I found this set of equation :
EQ1: I=Ic3(1+1/Beta3)+Ic4(1+1/Beta4)
EQ2: Ic1/Beta1+Ic2/Beta2=Ic4-Ic2
EQ3: Iout=Ic3-Ic1
EQ4: Ic1(1+1/Beta1)*...
- 69
1
vote
4
answers
101
views
Can differential probes be used with floating oscilloscopes, such as handheld/tablet scopes?
I am in the market for a differential probe (and possibly a handheld oscilloscope down the track for field work). One seller I came across has a warning for many of the probes that they sell saying &...
- 355
0
votes
1
answer
85
views
Distortion in a negative channel of the differential amplifier THS4505
I designed a single-ended to differential signal amplifier using a tool provided by Texas Instruments:
The source signal passes through a voltage follower (OPA810IDBVR), so the output resistance ...
- 75
0
votes
0
answers
81
views
differential gain for mismatched \$g_m\$ in differential amplifiers
I couldn't understand how the author came up with the expression of differential mode gain. He states to look from the Fig 4.17 to derive this expression, whereas the fig 4.17 has no mention of \$R_{...
- 13
0
votes
0
answers
182
views
Gain bandwidth calculation of two stage op-amp
I want to design a two stage single ended OTA without using a Miller compensation capacitance.
Every source that I have examined gives a design example with a compensation capacitance.
Hence, they ...
- 175
1
vote
1
answer
118
views
Differential Amplifier Output Ringing
I designed this circuit. It is a fully differential amplifier of gain one. I am getting this ringing and noise on the output of tx1_o
Blue is where the probe is and ground is on circuit's ground.
Here ...
- 11
0
votes
2
answers
70
views
How can i obtain a positive Vref for this circuit?
I have to design a irrigation system that uses a resistive moisture sensor to maintain a certain level of relative soil humidity for a plant. In order to convert the resistance changes of the moisture ...
- 41
0
votes
0
answers
76
views
Differential input resistance of non-symmetric circuits
In Sedra and Smith (7th edition, section 2.4.1) when building up to an instrumentation amplifier there is discussion of how to use a single op-amp (differential input, single-ended output) to ...
- 705
2
votes
1
answer
400
views
Why does my common mode test still have tiny retained sine wave?
I used this equipment the BMA-200 with the AMP01 having a CMRR of 125dB.
I connected the signal generator output to both the In+ and In-. Yet the waveform still have retained sine wave of very small ...
- 853
0
votes
0
answers
42
views
Noises when unused inputs not shorted with common V-
Update. Manufacturer confirmed all the 4 red V+ inputs used same blue V- and ground. Now what would be the noises introduced if only channel 1 is used and the 3 other inputs are floating (all ...
- 853
0
votes
2
answers
97
views
PCB trace impedances of integrated circuits with high input impedance
There is an ADC front end IC (opamp) at the input of my ADC card and it has high input impedance,
What should I set the differential trace impedance to when drawing the PCB? Does this matter much?
- 772
2
votes
1
answer
162
views
Unknown 958Hz peak in amplifier/ADC with any input (shorted, opened, signal generator, real signal) [closed]
Update 2: I disconnected the ground between channel 1-4 from channel 5-16 and the 958Hz peak disappears. It could be crosstalk but i wonder why crosstalk can produce 958Hz noise.
Update: Using the g....
- 853
5
votes
4
answers
553
views
Ground in differential opamp situation
I have a setup like such in the provided schematic.
The idea is that I do have a -2.5 to 2.5V signal which I'd like to convert to a signal between 0 and 5V.
How should I connect my opamp? Should the ...
- 376
3
votes
2
answers
497
views
How to share a single gain resistor among multiple op-amps in a circuit
I'm currently designing a circuit where I need to implement multiple op-amps, each configured with the same variable gain resistor using a single digital potentiometer.
To simplify the design and ...
- 33
0
votes
1
answer
48
views
Negative Voltage at Transistor bases in my Differential Amplifier
I am supposed to calculate the differential input resistance but the voltage at the base of the transistor is negative so according to my formula I will have a negative resistance which is most likely ...
0
votes
1
answer
125
views
Noises are measured over a bandwidth. Is 50Hz and 900Hz noise the same at 1kHz bandwidth? [closed]
They say noise is over a bandwidth. At a bandwidth of 1000Hz. Is the noise at 50Hz and 900Hz similar? If yes. Please made a quick drawing how the noise at 50Hz and 900Hz look like roughly so I can ...
- 853
0
votes
2
answers
169
views
How to measure fully differential amplifier input impedance in PSpice?
Before the differential ADC, I have a fully differential amplifier as the front end. I want to simulate and measure differential input impedance.
My working range is max. 20 kHz.
Why am I using the ...
- 772
4
votes
3
answers
244
views
How does the current and voltage stabilize in a differential amplifier?
I am trying to learn how differential amplifiers work, and I would like to be able to visualize how the voltages and currents stabilize if the input voltages are changed. Specifically, I'm caught up ...
- 363
3
votes
1
answer
72
views
3x analog signal multiplier
I was looking for sin(x) in, sin(3x) out. I am aware of PLL, diode, and AD632 multipliers. Most are either squarers for sin(2x) or pure sine or amplitude multipliers.
I saw the sin(a+b) identity and ...
0
votes
2
answers
80
views
LM3900: different input impedances in symmetric pins?
Referring to the LM3900 "Quadruple Norton Operational Amplifiers" datasheet, consider the schematic of each single amplifier at page 1.
simulate this circuit – Schematic created using ...
- 748
1
vote
1
answer
144
views
How is the boundary of input CM level calculated?
I will briefly state my understanding of the following equation, and then pose three questions at the end.
Equation (1) (2) refers to the circuit in the first picture, Equation (3)(4)(5) refers to the ...
- 113
1
vote
2
answers
222
views
Designing a differential amplifier
I was trying to design a differential amplifier in which the collector resistances of the transistors are 2.2 kΩ and are biased at 1 mA and are supplied with Vcc= +/-5 V . To find the Ro (the ...
- 43
2
votes
2
answers
104
views
Why does shorting the drains linearize the transconductance of the differential amplifier?
Why, by shorting the drains in Fig \$14.15\$ in this manner, will it allow the \$G_m\$ plots to add together? What will happen to the \$G_m\$ plot if we swap the shorting transistors, i.e., shorting ...
- 113
3
votes
1
answer
174
views
How to break the feedback loop and add the loading?
I am trying to break the feedback loop of a fully differential amplifier and add the loading to the input and output:
I want to do this to take into account the loading of the feedback network on the ...
