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ldo stability
i need the papers about loop stability in low dropout regulators thanks...
Analog Circuit Design :: 12 Oct 2009 10:45 :: mtechvlsi :: Replies: 35 :: Views: 4545
how to generate negative voltage?
p, the average output current is about 100ma through this voltage. except the charge pump chip, how can i realize a negative voltage with simple method on pcb? #2.i also need a big size mosfet (power transistor?) with source follower connection for ...
Analog Circuit Design :: 23 Sep 2009 7:08 :: FvM :: Replies: 2 :: Views: 333
dc fan control using ni - daq 6009 analog output
hey guysi have a dc fan that works between 3 and 10 volts and needs 1a. i need to control it using a daq 6009 by varying the output voltage at the analog output of the daq. i am well aware that the daq cannot give the necessary current that the fan n...
Power Electronics :: 14 Sep 2009 5:33 :: pauloynski :: Replies: 3 :: Views: 264
how to translate signal to a different voltage level
greetings,i am an amateur in this things and i am stuck with this problem:i want to interface a signal to an adc, but the signal is outside the limits of my adc. so, what i am trying to do is basically, without altering the original signal to run it ...
Electronic Elementary Questions :: 29 Jul 2009 9:35 :: rituparnasaikia :: Replies: 6 :: Views: 588
h bridge design, technical question about transistors
hello,im about to build an h bridge for a buzzer.i find the following circuit very interesting, but i will not use the opto-coupler.i was wondering why the pnp transistor were at the top ? i build one from myself and i putted the pnp at the bottom o...
Analog Circuit Design :: 19 Jul 2009 23:32 :: Kral :: Replies: 3 :: Views: 288
mosfet turning completely on
i seem to be having a problem turning on a mosfet completely. i am using a 2n7000 n-channel mosfet hooked up to a logic gate which is controlling the gate of the mosfet. however, the logic seems to be unable to turn on the mosfet all the way. until t...
Electronic Elementary Questions :: 16 Jul 2009 2:22 :: Audioguru :: Replies: 6 :: Views: 585
low pass filter with pmos input differential pair
i designed a low pass filter. it has a pmos bias at the top, a pmos input differential pair and a nmos current mirror as an active load. then connect the output to the negative input form a unity negative feedback. finally a capacitor is connected to...
Analog Circuit Design :: 13 Jul 2009 6:33 :: amitjagtap :: Replies: 3 :: Views: 309
output voltage of a transistor circuit
in the circuit below, when logic function commands low, the following explanation is given:1: for small load currents, q3 remains in the active mode, and the output voltage is a function of the drop across the 1.6-kΩ resistor, vbe3, and vdiode2...
Electronic Elementary Questions :: 26 Jun 2009 13:57 :: trekkytekky :: Replies: 4 :: Views: 226
h-bridge - should a maximum of 5 v appear across the load?
i wanted to know a little about h-bridge... lets say i made one using 4 npn transistors... the switching voltage at the base of each transistor is 5 v and 50 volts are at the collectors of the upper transistorsnow, as the upper two are in emitter fol...
Microcontrollers :: 25 Jun 2009 15:50 :: elrayes :: Replies: 2 :: Views: 300
jfet source follower gain problem
hi,ive been attempting to simulate a jfet source follower (common drain) and was expecting to get something near to a gain of 1. i understand that i would never get a gain of exactly 1, but near enough. however, i was getting nowhere near. more li...
Analog Circuit Design :: 30 May 2009 9:02 :: FvM :: Replies: 21 :: Views: 1287
how to make a unit gain amplifier ???
hi all i am working on my masters project on phase lock loop . i have to make a unit gain amplifier to include it in my charge pump design . i was wondering how to make it with few complications . also can i use 2 inverters connected in series ??? i ...
Analog Circuit Design :: 23 May 2009 22:32 :: FvM :: Replies: 18 :: Views: 1272
help about transister biasing
hello friends i have a problem. i am interfacing a proximity switch with plc. the switch is npn. when it detects an object it gives me 0v at output and when there is no object it gives 24v or 12v depending on its input voltage. this ...
Electronic Elementary Questions :: 02 Jan 2009 16:32 :: siongboon :: Replies: 11 :: Views: 576
constant current smps
hello,i am doing isolated , offline, one transistor forward converter for ~10 w output.i have a valley fill circuit after the diode bridge so my input dc bus ripples from 170v to 340 v.the secondary is set up to provide a constant current of 1 amp si...
Analog Circuit Design :: 11 Dec 2008 19:24 :: eem2am :: Replies: 12 :: Views: 2004
transistor as a switch- configuration of bjt to driving leds
hi dear friends,in your opinion whats the best configuration of bjt to driving leds (dotmatrix, big 7-segments, …) ? why common-collector is not suitable for switching heavy loads?is there any an or reference to study more about this subject?regards,...
Microcontrollers :: 28 Nov 2008 20:01 :: FvM :: Replies: 2 :: Views: 240
100 watt dimmer circuit!!!...help
please help me with this hardware design. a circuit is to be designed such that the incandescent bulb(100 watt) connected to it reaches its maximum intensity and then dims off as slowly as possible. it should be taken care that that the circuit shoul...
Electronic Elementary Questions :: 30 Oct 2008 22:03 :: Sinisa :: Replies: 9 :: Views: 645
how to set drain voltage (vd)
hi all,we know that id=kw/l(vgs-vth)^2 (saturation- first order). from the equation we can get voltage at vg and vs depending on the info that we have (i.e i is fixed or w/l is fixed). from the above equation, i dont see vd term in the equation. so, ...
Analog IC Design & Layout :: 29 Sep 2008 17:52 :: sutapanaki :: Replies: 9 :: Views: 351
linear regulators?
why do you use npn on the high side and pnp for low side when designing a linear regulator?...
Analog Circuit Design :: 15 Sep 2008 11:53 :: saro_k_82 :: Replies: 1 :: Views: 195
how to bias a transistor
could anybody tell me how to bias a transistor? on what factors does the bias depend?also, please tell me how to substitute a transistor with entirely different one and how to bias the new different transistor. how to bias an oscillator and tuned rf ...
Electronic Elementary Questions :: 18 Jul 2008 5:18 :: xulfee :: Replies: 1 :: Views: 159
base resistance
hi, folks.i would like to know why the resistor for the base of 2n3053 is 330 ohmshow do we calculater it ?here is what i think:in a transistoric=iehfe = ic/ibib= ic/hfesince ie approximately equals to ic let ie be 300ma and hfe be 100ib = ie( 300m...
Electronic Elementary Questions :: 13 Jul 2008 14:29 :: simonwai999 :: Replies: 11 :: Views: 243
after this differential amplifier, is a buffer needed?
hello all,a differential amplifier is implemented in my circuit( please see the picture in the attachment). the amplifier shown in the attachment is composed of a differential-input single-ended transconductance output stage and a source follower as ...
Analog IC Design & Layout :: 29 May 2008 14:36 :: FvM :: Replies: 3 :: Views: 222
zero vt nmos for tail current
hi all!is it good to use zero vt nmos for tail current for opamp? because the tail current will sink 10 ma, if use normal transistor, the size will be big, any issue if i use zero vt transistor for tail current?thanks...
Analog Circuit Design :: 17 May 2008 20:46 :: sutapanaki :: Replies: 10 :: Views: 402
optical electronics and optical effects questions
im trying to learn more about optical electronics mostly about lamps+ldrs what do you guys know about optical electronics and how lamps or leds with ldr circuit/networks react and characterists?1.) the distances or spacing of the lamp to ldr makes a ...
Electronic Elementary Questions :: 13 May 2008 5:11 :: walters :: Replies: 9 :: Views: 522
beta helper
hello all:a bipolar current mirror with beta helper is aiways used. sometimes i can see that a resistor is connected between the common base node and the ground. but in classic books ,such as gray and meyers book,there is no resistor fron the common ...
Analog IC Design & Layout :: 04 Apr 2008 6:12 :: Alex_IC :: Replies: 2 :: Views: 228
is this a class ab source follower?
hi all,i read about a so-called class ab source follower buffer, as in the figure. according to the definition of class ab, when vin increase/decrease, one of the output transistor goes off. but for this circuit, when vin increases, vo also increase...
Analog Circuit Design :: 03 Mar 2008 2:54 :: CherryQ :: Replies: 5 :: Views: 270
[need help] dc motor blower speed control
hi all,i want to control my dc motor blower speed. the motor blower have 15 amperes current maximum in high speed at about 12.5 vdc from lead acid battery voltage.i found from internet a darlington circuit configuration for motor speed control using ...
Hobby Circuits and Small Projects Problems :: 28 Feb 2008 9:03 :: CyberBrite :: Replies: 13 :: Views: 1700
small signal amplifiers
can someone help me in designing this amplifier with a input impedance of 100 ohms, output impedance of 76 ohms and a voltage gain of 60db using a 2n22222 transistors. ...
Analog Circuit Design :: 26 Feb 2008 6:11 :: -jps- :: Replies: 9 :: Views: 321
what is a floating diffusion(fd node) in image sensor pixel?
what is a floating diffusion(fd) exactly?in most figures it is illustrated as aparasitic diode,or maybe including the parasitic gate cap and parasitic drain/sourcediffusion cap(not sure about this)?but why it is called fd node?...
Analog IC Design & Layout :: 21 Feb 2008 23:32 :: timof :: Replies: 8 :: Views: 456
who can understand this circuit???
hi ive a question about the attatched circuit.in this circuit, gate is fixed 6.3vand box is load.when i sweep drain voltage, vs is raise up with vd.but when vgs~vth, vs stops raisingand current remain constant.i think mos is used as switch at first, ...
Analog Circuit Design :: 12 Feb 2008 21:31 :: sutapanaki :: Replies: 7 :: Views: 567
pnp non-inverting driver
tter=un-know logic? the design is it correct? the 7405 output is open-collector, if the 7405 input is un-know logic so what is the actual 7405 output? how to design the non-inverting driver using pnp transistor?thank you...
Electronic Elementary Questions :: 18 Nov 2007 7:16 :: IanP :: Replies: 3 :: Views: 123
inverters
how to invert car battery 12v dc to 230v ac...
Hobby Circuits and Small Projects Problems :: 16 Nov 2007 12:43 :: babatundeawe :: Replies: 7 :: Views: 555
how to deal with the high input voltage of ldo
5v to 3.3v/1.8v ldo, design with 5v tolerance 0.18um process. due to the 5vinput voltage,the voltage between the drain and gate of the power pmos transistormay exceed 5v, it may cause the transistor to break down,how should i deal with this situatio...
Analog IC Design & Layout :: 11 Sep 2007 7:49 :: leo_o2 :: Replies: 14 :: Views: 792
differential amplifier..friends plz help ...
hi allexample attached with this mail is of razavi chapter -9here it is showing that vin min = 1.3vbut i think vin min = vt (m1) + vds ( current sink -> iss) = 0.7 + 0.3 = 1vcoz i think as m1 vgs= vt it directly come into saturation m i right or wron...
Analog Circuit Design :: 05 Jul 2007 9:23 :: noiseless :: Replies: 7 :: Views: 267
what is buffer?
what is buffer and the use of buffer,when doing circuitry design?for example..when i use photodiode to detect the intensity of optic source..and the output current changes linearly with incident light and the voltage output changes lagarithmaically ...
Electronic Elementary Questions :: 19 Jun 2007 18:31 :: azaz104 :: Replies: 7 :: Views: 375
questions on thermal noise cancellation
hi, there anyone who reads bruccoleris paper of wide-band cmos low-noise amplifier exploiting thermal noise cancelsing may help me on some questions 1. how to mitigate the noise generated from the source follower in the second stage? 2. how to mi...
Analog IC Design & Layout :: 17 May 2007 13:26 :: Julian18 :: Replies: 4 :: Views: 417
low voltage audio amplifier
long time-reader and first-time poster. heres what im doing: i am working on a low voltage amplifier using bjts. tthe input comes from a pc or mp3 player (around 200mvrms). i want the voltage gain to be higher than 10v/v and 1w should be dissipated t...
Analog Circuit Design :: 13 May 2007 17:23 :: boh :: Replies: 3 :: Views: 786
ldo with nmos as pass transistor..
i need help in designing the ldo with nmos as passtransistor..the gate voltage of the nmos should be higher than the input voltage..i need to use a chargepump to get this high voltage..anybody has any experience in this.. any material is appreciated....
Analog Circuit Design :: 10 Apr 2007 13:11 :: drabos :: Replies: 11 :: Views: 450
why the tail resistor can increase the amp's stability
hi,everyone : i read a patent (us6407537) , it is said that the tail resistor can increasethe stability . may anyone explain it ?http://images.elektroda.net/26_1170235850.gif...
Analog IC Design & Layout :: 27 Feb 2007 9:14 :: jinnose :: Replies: 26 :: Views: 420
some questions about class ab op amp
dear all: i am confused by class ab op amp. as we all know, class ab have better power effiency than class a op amp. but it is always used to drive resistance load.if its used to drive capacitance load, i have some questions below:1. how to det...
Analog Circuit Design :: 08 Dec 2006 4:33 :: winsonpku :: Replies: 5 :: Views: 507
urgently,about subthreshold circuit design in cmos process
all, i meet a puzzle problem. in voltage follower design, i find many transistors in threshold region and the performance is good for large power supply variation. according to the general rule, the transistors should be in active region. i get the...
Analog Circuit Design :: 02 Dec 2006 4:10 :: manish12 :: Replies: 3 :: Views: 339
a crictical op-amp question!
ple question:when a 2 stage op-amp is connected in voltage follower configuration, when an input signal is applied, how will the internal node voltage of the opamp change? e.g. the drain of the input transistor? it seems it cannot be changed too much...
Analog Circuit Design :: 28 Oct 2006 19:53 :: isaacnewton :: Replies: 3 :: Views: 228
rf amplifier @ 200mhz
hi ...i want to build a 30 db rf amplifier for vhf range (from -40dbm to -10dbm), so i use two stages of 15db ce transistor amplifier(bf199) .every stage work great @ 200mhz , but when i connect them together..the signal is distorted !!!!!!!!i try to...
RF, Microwave, Antennas and Optics :: 28 Oct 2006 3:17 :: kawish :: Replies: 20 :: Views: 3875
analog design : some things to remember
know that i found helpful over the years.1/ capacitors and resistors have parasitic inductance, about 0.4nh for surface mount and 4nh for a leaded component.2/ if you dont want a high bandwidth transistor to oscillate place lossy components in ...
Analog Circuit Design :: 22 Oct 2006 20:03 :: E-design :: Replies: 17 :: Views: 5235
basic troubleshooting formulas
what are some basic troubleshooting formulas to use when u troubleshoot circuits ?what are some critical troubleshooting formulas u must use when doing troubleshooting any circuit?1.) use ohms law to calculate resistor voltages,voltage drops,currents...
Electronic Elementary Questions :: 12 Oct 2006 3:12 :: walters :: Replies: 12 :: Views: 504
urgent:how this amplifier works
hello there i want to know how this amplifier worksas i understand it is a differential two stage amplifier and the first stage with pmos i/p and loaded by 2 nmoss as current source so we must insure same vg for both so the bjt is used but i dont kno...
Analog IC Design & Layout :: 20 Jun 2006 16:44 :: JPR :: Replies: 2 :: Views: 252
hard feedback question !!
15 point for everyone who give true answer!hihttp://electronicspace.persiangig.com/image/2.jpg1- what is the feedback topology in this circuit?2- what is the beta (feedback factor) in this circuit?and why?regards...
Electronic Elementary Questions :: 24 Apr 2006 4:50 :: teteamigo :: Replies: 15 :: Views: 528
bleed resistor
refering to the attachment that the left composite circuit is equivalent to the right pmos, but has much higher current driving capability. my question is about the bleed resistor. some book says the reason of existance of the resistor is twofold: on...
Analog Circuit Design :: 09 Apr 2006 3:41 :: youyang :: Replies: 3 :: Views: 240
current controlled source
hi all.in current controlled voltage source for ex:a bipolar transistor,if current controlles o/p voltage ,from where this input current comes. it should have voltage no...then how this become current controlled..pandit...
Electronic Elementary Questions :: 09 Mar 2006 15:36 :: Hughes :: Replies: 2 :: Views: 177
why using pmos at input stage
in many books, they say pmos is good to be used in input stage due to its offset and noise performance. i heard about that it is due to its large size and low mobility. can anyone further explain this?...
Analog Circuit Design :: 04 Mar 2006 7:49 :: avinash :: Replies: 19 :: Views: 1098
low voltage buffer
helloi am working on low power ldo. first i did simulation with simple one stage ota (nmos input) plus power pmos and feedback. the lowest vdd is 1.3 so pmos has to be quite big to drive 100ma. ota has big output resistance, when working with low bia...
Analog Circuit Design :: 13 Feb 2006 9:44 :: jutek :: Replies: 2 :: Views: 237
voltage follower with pmos
i have voltage follower with two pmos transistors in series. constant dc voltage is given to the gate of 1 transistor and input is give to the gate of other transistor and is biased with vdd(3.5v) and vss(gnd).when i simulated this circuit in the cad...
Analog IC Design & Layout :: 12 Dec 2005 7:31 :: matlabprob :: Replies: 5 :: Views: 348
ota amplifier and voltage amplfier comparison
guys,need some feedback on the ota and voltage amplifier. as we know that voltage amplifer will have low output impedance and we can say it sense input and output as voltage to voltage whereby ota will have high output impdeance and will sense voltag...
Analog Circuit Design :: 18 Nov 2005 3:52 :: scottieman :: Replies: 3 :: Views: 798
lvpecl driver interface
ave common mode of 2v at the emitter follower and the swing about 800mvpp single ended. my question here is, what will be the value of the resistor we have to design here at the emitter of the output transistor. does it need to be 50ohm as to match t...
Analog IC Design & Layout :: 05 Aug 2005 10:13 :: elcielo :: Replies: 1 :: Views: 150
help required with voltage reference generator circuit
please look at the following circuit. the input to the op amp is from a bgr. the op amp is a p-input 2 stage miller ota. the problem is that when im doing a transient analysis, all the reference nodes start oscillating as i ramp up the supply. why is...
Analog IC Design & Layout :: 28 Jul 2005 4:17 :: aryajur :: Replies: 7 :: Views: 438
mosfets unexpectantly hot!!!
i have three mosfets (buz11) turning on and then off in a row and then repeating the sequence. the mosfets are driving the coils of a hdd motor. after some time, i smelt that familiar hot smell and the mosfets were literally on fire. they were unbear...
Analog Circuit Design :: 18 Jun 2005 9:47 :: HINDI :: Replies: 20 :: Views: 960
put resistor at base of bjt of bandgap circuit
hi all : i have a question... in a bandgap circuit , if put 2 resistors (rb1 ,rb2)at base for those 2 bjts, what benefits can the circuit get ? thanks a lot....
Analog IC Design & Layout :: 13 Jun 2005 5:58 :: gszczesz :: Replies: 18 :: Views: 639
cascode current mirror of bjt
for mos transistor, i have known that the cascode current mirror will put a higher output resistance and therefore it will dicrease the channel length modulation effect.the formula is : rd = 1/ λidi have understood that , when we put the curren...
Analog IC Design & Layout :: 29 Jan 2005 7:53 :: sutapanaki :: Replies: 2 :: Views: 465
a strange structure about operational amplifier
this op is used as a error amplifier, how can i calculate the gain ?and what are thr merits of this structure?3ks...
Analog Circuit Design :: 23 Jan 2005 20:29 :: sutapanaki :: Replies: 15 :: Views: 1254
pass transistor
what is the function of pass transistor in the high current power supply design?...
Analog Circuit Design :: 27 Sep 2004 17:05 :: FoxyRick :: Replies: 1 :: Views: 438
bandgap circuit and simulation.
it is a bandgap design, the picture below is the schematic. bandgap output voltage is 1.22v, and i need 2.1v output voltage. the m1 and m2 are diode-connected as resistors. it very hard to design w/l of m1&m2. the simulation result is very strange. i...
Analog Circuit Design :: 26 Sep 2004 20:54 :: electronrancher :: Replies: 18 :: Views: 1179
simple digital power supply
hi,i need to design a simple 0-5v digital power supply to ease my life in the lab.producing 0-5v with a dac is baby toy for all.what i need is a power efficient block that can increase my output current. my current microcontroller supplies 40ma for ...
Analog Circuit Design :: 25 Sep 2004 23:06 :: Free_Will :: Replies: 8 :: Views: 1041
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differential apmplifier
hello,doesnt anybody know how to build a differential amplifier with high input impedance and only two oz ?...
Electronic Elementary Questions :: 23 Sep 2004 23:54 :: savadi :: Replies: 13 :: Views: 1611
variable output voltage
hi, i need to design a circuit that can output different voltage outputs(variable, say from 3v to 10v) based on certain ttl inputs from a microprocessor. the circuit should be low output impedance. i was thinking of using a digital potentiometer conn...
Electronic Elementary Questions :: 16 Aug 2004 16:30 :: Kevin Weddle :: Replies: 9 :: Views: 1269
level shifting in cmos
helloquestion about level shifting in cmoswould you use a source follower everywhere or just resize tranistors so that the vds changes and then changes your common mode levels ?i have heard source followers in cmos are garbage (poor gain, frequency r...
Analog IC Design & Layout :: 06 Jul 2004 16:01 :: staric :: Replies: 4 :: Views: 708
troubleshooting a vco 145mhz
hello everybodyi am working in a vco that can be seen here http://www.eurobotics.org/vco/vco.htmlthe oscillator works good, good frequency good shape but when i introduce the varactor i dont get what i would like to have, that is a 2 pick signal one ...
RF, Microwave, Antennas and Optics :: 02 Jul 2004 2:28 :: vco96 :: Replies: 5 :: Views: 315
how to find offset voltage
hi,how can i find the offset voltage of a two stage opamp? thanks a lot! :)...
Analog Circuit Design :: 19 Jun 2004 9:47 :: zwei78 :: Replies: 7 :: Views: 725
0.2 ohm resistor for bipolar process
hi,i need to put 0.2 ohm resistor between output transistors emitter and ground for dc-dc convertor.output current is about 400 ma.resistors tolerance is 30%.process - bipolar, 15v.uladz55...
Analog IC Design & Layout :: 20 May 2004 2:46 :: uladz55 :: Replies: 22 :: Views: 1899
voltage reduction
i need to reduce voltage from 5vdc to 2vdc, can anyone tell me how to do this and how to connect multimeter to check??i thought i knew, but stubbornly stays at 5v!!!...
Analog Circuit Design :: 18 May 2004 12:42 :: atmaca :: Replies: 8 :: Views: 1305
5-3v regulator design
who can provide me a circuit design of translating 5v supply voltage to 3vwith low power dissipation?input voltage: 3-6voutput voltage: 2.7-3.3vicc: <20ua...
Professional Hardware and Electronics Design :: 29 Jul 2003 12:13 :: penrico :: Replies: 7 :: Views: 567
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