# Questions tagged [input-bias-current]

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### Noninverting input voltage seen on V+ pin of OpAmp

I've built this exact circuit here, except for one variation: SHDN is connected via a 10K resistor to ground. The opamp should be off!!! What happens is when I connect a battery (or power supply) to ...
• 709
114 views

### Measuring low Input Bias current of cmos op amp

I am trying to test the input bias current of the following CMOS RRIO Opamp: TP2412 I am going to follow some similar circuits like these two shown in another op amp datasheet. I know that these are ...
3k views

### Why does this op-amp circuit require a resistor to ground?

The text in section 4.1 of Designing With Opamps - Part 1 reads: Rin is the input resistor, and is needed because an opamp needs a reference voltage at the input. I don't see a similar resistor-to-...
• 81
1 vote
2k views

### Op-Amp's offset voltage and bias current

The following Op-Amp is ideal, except of an offset voltage at the input : Vos = +-10mV, and a bias current: Ib = 10uA. I am supposed to find the value of R in order to compensate for the effect of Ib ...
• 179
50 views

### Maximum absolute voltage deviation at the output (with systematic imperfections)

The opamp here is ideal except for the bias currents. In order to calculate the maximum absolute voltage deviation at the output, I was thinking of sum the deviation of Vos and deviation of current, ...
71 views

### 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 ...
2k views

### 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
204 views

### 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. ...
• 1
290 views

### 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 ...
• 233
1 vote
275 views

### 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 ...
166 views

### 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 ...
• 1,461
412 views

### 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 ...
798 views

### 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
216 views

### 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 ...
• 377
146 views

### 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 ...
• 22.3k
Without the feedback resistor, $\frac{v_{in}}{R}$ current flows through the capacitor and charges it to $v_{out}(t) = -\frac{1}{RC}\int\limits_0^tv_{in}\,dt$ Good so far. My textbook says a ...