Questions tagged [input-bias-current]

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Op-amp current values

In this App note, page 7, example 3, can someone tell me from where the values for IBN and IBI are coming from? I.e. \$I_{BN}\$ = -(5 nA + 0.5 nA) \$I_{BI}\$ = (5 nA - 0.5 nA) I'm using this MCP601 ...
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9 votes
6 answers

Why do we need R1 in a non-inverting op-amp?

I am quite new to learning op-amps. What is the purpose of putting R1 there? Does this have any meaning in the design of a microphone amplifier? I read about this from another answer, which says that ...
  • 91
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1 answer

I added a bias tee to a visible light communication (VLC) link for faster modulation. Why is there no signal coming out?

I am working on a simple VLC link. A square wave input with 1 MHz signal is coupled with the direct current (DC) by a bias tee (mini circuits ZFBT-4R2GW-FT+) to drive the lighting of the white LED. ...
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3 votes
1 answer

JFETing op-amp inputs

My goal is to be able to use a high-speed, low-distortion, BJT-input op-amp having a much lower input current - that's why I'm trying to JFET the inputs. I don't want to cut DC with input cap, I want ...
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1 vote
3 answers

How to fix hot PWM and crack 6A High-Speed MOSFET Driver?

My boost converter boosted voltage for a few seconds but it made a crackling sound, probably burnt. It doesn't switch the MOSFET now and TL494 is getting hot from the upper side which is where error ...
2 votes
0 answers

Input bias incorrrect in stock LTspice model

I am trying to use the AD8067 in LTspice (v17.0.33.0). The model for this opamp ships with LTspice. I have rigged it up as a follower, and I am seeing 150pA input current. Per the datasheet it should ...
  • 1,396
0 votes
3 answers

AC coupled differential op amp bias current return path

I have a unity gain differential op amp, using a grounded dual supply, with both inputs AC coupled. Does the inverting input need a dedicated path to ground or can the DC bias current find its way to ...
5 votes
3 answers

Problem with simple non-inverting NE5532 configuration

I am building a small amplifier which is working just fine. While experimenting I interchanged the TL072s with NE5532s and the amplifier stopped working, so I set up a simple non-inverting amplifier ...
1 vote
1 answer

How can one supply an external bias current?

Please refer to this opamp design. Suppose all MOSFETs are to be fabricated on chip. The bias current is to be supplied externally. How can this bias current be supplied externally? For example, can ...
  • 367
2 votes
0 answers

Op Amp Input noise and bias current relation with input quiscient current

I am trying to understand how varying the input differential pair quiscient current in an op amp will affect its: a) input bias current, b) input current noise, c) input voltage noise. Based on ...
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