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# Biasing Circuits

60 Threads found on edaboard.com: Biasing Circuits

## Ic package ground plane

Inside an IC package, what is the purpose of ground plane. Is it connected to the backplane of substrate for biasing it. Is it useful only in high frequency RF circuits or required for low frequency analog and digital circuits also.

## TL431: Do i need to limit voltage reference input current?

If you look at the equivalent schematic shown in the datasheet directly below the functional block diagram, you surely understand how a high reference input current can be generated - by forward biasing the Ref-Cathode (base-collector) diode. This won't happen in a typical application, e.g. the datasheet reference circuits, but can happen under ci

## Vref, Bias and Vint part of circuit. what are their voltages?

There is a biasing/reference voltage generator in it and resistor is used to define internal bias current in the IC.Cap has been used to get a stability due to feedback nature of these kind of circuits.These voltages should normally be expressed in its datasheet.If not, you have to follow recommended values as are..

## Circuits for high voltage to ADC reading. Problem with simple voltage divider

You over complicate it! The output voltage of that circuit can never go negative because there is no negative voltage supplied to it, however, by biasing the + (non-inverting) input at half supply voltage, you have offset the output by 2.5V even when there is no input voltage. I think you are mistaking voltages below 2.5V as being negative. Howeve

## 3 phase input supply to adc

I presume it's a pseudo-differential ADC input that requires positive common mode voltage on the differential pins. So additional biasing circuits are needed. Preferably buffer amplifiers should be used. You also didn't tell if you want to measure the instantaneous input voltage with respective fast sample rate or use an analog circuit to conve

## ISCAS Benchmark simulation in HSpice

I want to add an complex biasing circuit and a switch to Iscas benchmark. Simulations have to be run in HSpice. I am not able to find a way to add these circuits to the benchmark. Could anyone please guide me.

## What is the difference between these two designs?

collector current depends on the base biasing as well as collector series resistor

## Need Help with derivation of biasing circuits for opamp

Hi Guys!! I am new to Analog IC design. Could some one please help me with derivation of biasing circuits for a complementary differential pair input for a rail to rail operational amplifier. (Please see the attached .jpg for reference ) Thanks! Saoni

## biasing a diode detector

All shown DC-biasing circuits can be used. The purpose of DC bias is to operate the P/N or Schottky junction at the best point where then open/closed" ratio offers the best rectification of RF input signal. Some circuits leave the DC-bias voltage at the DC or video output. THe best solution is to use a pair of detector diodes connected to (...)

## Common-emitter biasing on an IC

Hi all, New here, recently discovered the resource. I have a question about biasing a common-emitter amplifier on-chip. I've done a good few audio amplifiers with op-amps or discrete transistors, and there a four-resistor network works well. However, I've now started working with Cadence for M.Eng research, and I've been trying to get a si

## low noise amplifier at ku band

Dear pujithakaza, There is no proper methodlogy for Microwave frequeny biasing ckt, you have randomely vary the resistors, will get the desired Vds and Ids. Because scatering parametes we don't have any method such that in the low frequency biasing circuits. Randomely you choose any biasing ckt such that (...)

I think the following link should be gives various biasing circuits which provide the right voltage at the gate without the extra threshold voltage which comes with the basic current mirror which gives headroom issues. To

There are many kinds of biasing circuits. Some are using transistors. Generally, the question text doesn't seem to fit the title. Try a clear question, preferably with a cicruit example clarifying the topic.

## Design of Current mode differential amplifier

I wanted to design an current mode operational amplifier with differential input and differential output as a part on my project. I have referred a few papers for the same but what I find missing in the papers is the biasing circuits required for the current mode op-amps. I need any reference that can provide me help with the biasing (...)

According to this paper a dual gate mosfet has significant advantages over common transistors and mosfets. It seems that information on the internet is quite limited. Any information about biasing, characteristics, examples in circuits will be valuable.

## Introducing DC shift/Offset to AC input : Trouble

I have designed a white noise generator. the o/p is very low, so i used amplifiers to take the level upto mV. I also need to incorporate a dc level to the o/p. I used many circuits for this prupose, but no dc shifting. I tried simple voltage divider, opamp ( Non-inverting ac coupled) biasing etc etc, result is same : no biasing. Here is (...)

## Leakage current in MOSFET

At 90 nm, reverse bulk diode biasing will reduce leakage during standby modes. Obvious other alternative is to power gate circuits not in active clocking. You can also employ dual threshold process option. Low threshold devices for speed, higher threshold for low leakage. You can combine the later two to transfer high speed memory to low leakag

## Confusion with biasing circuits (BJT)

Hello experts! I was studying biasing circuits i.e. voltage divider bias, base bias, emitter bias, and both feedback biasing circuits i.e. collector feedback bias and emitter feedback bias. Analysis of all these biasing circuits are so confusing. In voltage divider bias, base circuit (...)

DC biasing or supply circuits are isolated from RF circuit by DC chokes,coupling capacitors etc. That's why, in an amplifier's simulation DC components are "at the beginning" considered ideal and then in later simulations, equivalent models or s-parameters or large signal models are used to optimize the amplifier's perfomance.

## Antenna diodes breakdown

a) if you look at any diode characteristic you will see that even reverse biased diode is still letting some current through. Not much but enough - you can actually use it for your design if you are careful. Very often it is used for biasing of substrate in case of "overvoltage" circuits. That said diode does not have to break down to provide curr

## best book to study bjt

plzz tell me the best book to study bjt, small signal parameters(h parameters, biasing in detail etc.. thanks

## Help regarding biasing in MOS amplifier circuits

What is the point of writing this way "B I AS I N G I N M O S A M P L I FI ER C I RCU I TS " , it is unreadable. Why don't you write it like biasing IN MOS AMPLIFIER circuits so that it is actually readable? Alex

## Beta Multiplier Reference

Hi, The circuit is same as a constant-gm biasing circuit used to generate bias currents. The current in nmos (those with gates to vbiasn) is (delta_vgs / R) and you can use vbias to generate bias currents in other circuits

First of all, what is the used substrate ? The impedances are defined by source pull and load pull simulation or measurement. And I don't see any biasing voltage in this schematic...

## how to choose cmos device size and bias for digital circuits?

What do you mean by biasing the digital circuits? If you ment the cml logic, the swing, and common mode voltage will define the tail current.

## Transistor operation in CE region(mainly saturation region).

I don't understand what you mean by 'CE region'. In a common emitter circuit used for switching, forward biasing the collector-base junction is undesirable - it slows down switching. That is why a Schottky diode is often added from base to collector in switching circuits. Keith

## Question about gate biasing of pHEMT amplifiers

I have a simple question. I measured a 2 different pHEMT amplifiers from 2 separate companies. I used GSG probes for the input and output, and DC probes for biasing the drain and gate. When I do this, the gain is signifantly lower than from the spec sheet. When I add a external 1k series resistor between the DC supply and the DC probe at

## How to calculate the biasing voltages of conventional folded cascode amplifier?

please tell me how to calculate the biasing voltages of conventional folded cascode amplifier.. i am attaching my circuits.. also tell me how to calculate the device sizes of mosfets... please reply.....

## Changing the channel length value from 180nm CMOS

It is all depend on the need of your circuit design and functionality. If your circuit is to operate in the wideband frequency, then the minimum L will be used, on the other hand, if it were to used for biasing circuits, or low frequency application, you can set your value to 2X and above as what others responded.

## can any one tell me what is replica baising ?

replica biasing is used in analog circuits where you want exact mirroring of bias currents with currents in active circuits eg. VCO design. Here the acitive part is circuit is replicated in bias circuitry , and same voltages should be maintained to exploit the use of replica bias . please see this , you may get some idea J. Maneatis, (...)

you don't need papers to design a biasing network. It's not really hard. In my opinion, there is no proper rules saying how to do according the device technology. But by simulation you will see what is the best way for your application. design engineers have often different point of view regarding this topic, you can hear all and the contrary.

## How to build a LED bargraph to detect 0V to 5V?

LM3914N or LM3915 is the cheapest and easiest and widely used IC to make a 10 LED bar graph. It can be calibrated to any full scale value required with chnaging the biasing resistors. There are other Ic's like LB1405 which will give 5 LED output. TA7666 with 2 x 5 LED output etc. Good luck

## biasing and cmfb circuits

Who can help me with an biasing circuit and a cmfb circuit for the attached LNA ? _Squ!D_

## how to simulate a PIN diode in CST?

And what about the biasing circuits?? did you simulated those to along with diode for more accurate results?

## Any one introduce "Biasing Circuits" to me?

biasing circuit is used widely in analog circuit design to bias circuit in proper operating point. let sat if you design opamp, all the transistors must be biased in saturation mode because in this mode we can get large gain. example of bias circuit is voltage reference circuit, current mirror/sink/source. it depend on your applications. hope my ex

## Class B RF Amplifier Design

Hi, I am currently looking at doing class B or class AB power amplifier design for RF application. Can anyone provide advise on designing the DC biasing and RF matching circuits for such amplifiers. Any help will be much appreciated. Thank you

## Bandgap Current Reference

Hi, I am looking for a bandgap current reference circuit (0.5u n-well process) to use it as a current source for biasing circuits. My understanding is that if a reference source is temperature independant it can also be considered process(corners) independent as many process parameters change with temperature? I came across this circuit

## why simulation don't show the noise from bias circuits?

Could be the case. If the circuit is symmetric to the biasing there is no noise from the bias generating circuit. That could lead to crazy noise effects. For instance if you have a differential signal the noise amplitude will be modulated with the signal. That is likely if you have a bias current generating source which has, mostly because of su

## supply-independent biasing circuit

Hi Guys I simulated the circuit in razavi's "design of analog CMOS integrated circuits" Chap 11.2, but the circuit never sucessful work in cadence, I am wondering if someone simulation Fig, 11.3 in that book, does it work? the circuit looks simple, does it because I missed a start-up circuit? Thanks a lot

## why diodes are connected in serial?

EDA_hg81, Diodes are often connected in series in biasing circuits so that their combined voltage drops will track the base-emitter voltage over temperature. . It is not a good idea to connect diodes in series to provide an increased reverse voltage rating. The reason is that if a voltage with a small rise time is applied, the voltages across

## How to bias bandgap circuit?

Usually bandgap circuits includes start up. After start you can use self biasing.

## how to do stability analysis for bandgap circuit?

Generally U shouldn't check phase margin in bandgap (and other biasing circuits), because result of AC simulation may be deceiving. But always check stability during transient analisys with slow and fast supply voltage ramp. I cite " Verification of the biasing cir

## request for transistor biasing software

hello i have a fm transmitter circuits using pn918 which works with a 1.5v supply. i want to increase the supply voltage to there any software that can help me do that.pls help me.

## XOR, D-flip flop and MUX circuit for a phase detector - HELP

Hi All, I am working on this project where I need to simulate the following circuits: > Figure 4.4 shows an xor gate. I need to know how it works and the different parameters I would need for its functioning (which are Iss, Vb I1 and R1) > Figure 4.5 shows a current-steering differential latch. I need to know what Vsource (biasing voltage sh

## What's the difference between 0.18um and 0.09um?

obviously the difference is vdd level. smaller voltage biasing should be used in 90nm to preserve headroom in order to remain all transistor in saturation.

## Explanation of 1/3 rule and 1/10 rule in BJT

these r designing rules u can learn these through "microelectronic circuits by sedra and simith 4th editon" see chapter number 4 in which four tecniques of biasing tranistor u see it in first technique of biasing

## How to design a bias circuit ?

Hi Your question has been defined very generally! If you want to find out biasing in analog integrated circuits (e.g. in Op amp) fundamentally, you may use famous books such as John & Martin, Gray & Hurst, Razavi, their chapters about Opamp design; in the first case chapter 6 is the best! but if you want to study for state of the art; I suggest

## The definition of biasing in electronic circuits

biasing means providing a voltage that overcomes or restricts the flow of carrier in semiconductor. No current will flow when any semiconductor is ubiased

## Ask for information of a PA module.

Hello, folks, Who has used the Triquint's PA module TGA2508? And what's it's performance. The biasing and matching circuits are quite simple, but in my prototype board, the test results are much worse than its specification. I'm confused by it now. Thank you!