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46 Threads found on edaboard.com: Bias Circuit Cmos
Hello everyone, I have been facing problem in designing a folded cascode cmos opamp. I have designed the mosfets aspect ratios for the amplifier circuit but i could not design the bias circuit. I admit i am not very good at designing circuits. so can people here help me with the bias (...)
Hello everyone, I was thinking in building a bias circuit to bias my circuits when I am designing them. I would like to know if it is a good idea to build some sort of closed box with several bias voltages and if some of you have done this. Is there someone who has done this kind of (...)
I am a first time analogue designer and need help with my Gilbert cell multiplier(cmos 0.18um technology). The problem is that my circuit doesn't bias correctly.I work in low frequency. the output that I need, the plot of four quadrant of multiplier. *Gilbert cell analog 5 .options brief *********************Main (...)
Hi, I am making a supply independent bias circuit as shown in Razavi cmos integrated circuit book (Figure 11.5). I simulated the circuit but it does not seem to work properly. See output current vs vdd supply curve attached with this email. Can some body help? circuit has following W and (...)
Hi, all, I'm using the TSMC 0.13um cmos proccess. I would expect some influence to the frequency response, for example for one amplifier stage, when I was using a huge resistor as the AC coupling bias resistor for the next stage. But the simulation results show almost no influence, and I found that the resistor, for example rphpoly, has no paras
in Razavi's cmos book Chapter 12, see figure below 82262 how to bias the opamp properly since the opamp is configured with capacitive feedback (C2) at both phases? thanks!
hi... u can refere 1. B.Leung, “VLSI for Wireless Communication”, Pearson Education Inc,2004. 2. B. Razavi, “Design of Analog Integrated cmos circuits”, Mc-Graw Hill, 2001. 3. Allen hollbergue, "cmos-Analog-circuit-Design" 4. T.H.Lee , "the design of cmos radio-frecuency entegrated (...)
All outputs open circuit. The comparator inputs want to be at different potentials to avoid chatter. It doesn't really matter which, bias current is relatively constant. As long as the ground connection is close-in a direct connection is fine. If it's a long "antenna" or there's a chance of offset then a few-K resistor is OK, but probably unnecess
Hello all, In razavi's design of analog cmos integrated circuit, chapter 3, it states/shows that body effect decrease the output resistance. But I find it puzzling. I bias the NMOS source with a certain voltage, eg 0.3V. Setup 1: Base and Source are connected together to 0.3V bias. (No body effect) Setup 2. Source (...)
The cmos version of 555 has a supply current demand in a 100 uA order of magnitude, so it can't compete with the low power transistor circuit. 555 is designed for up to MHz rate, so it needs a higher bias current. But the output will a clean rail-to-rail squarewave.
... 1. To generate a bias current why is a PTAT current generator used. The current will be proportional to absolute temperature so won't that affect the circuit performance. Instead shouldn't a bandgap reference voltage be generated and then use that voltage to generate the bias current? ... 3. ... Again I don't understa
cmos>>68R>>..|>1n4148... base add a 1k res between 1n4148 cathode and ground the 68R resistor limits any current from the cmos i/o more than desired the diodes gets rid of .7v the 1k to ground allows for the right bias lift up from diode cathode use a bd139 in this circuit
Break it down into pieces. Some devices are only used as capacitors. Some are only for limiting voltages and the rest is only a very simple bias and protection voltage generation circuit. It is basically what adamantiumxx told you to analyze. You can find analysis in any cmos circuit design book. You might want to (...)
good day everybody.. i'm doing simulation right now about high swing cascode current source. this is about the self bias high swing cascode current source. please refer below for the figure. (i found this circuit in cmos Analaog Design by Allen, 2nd edition page 133.) In this configuration, he eliminates an Iref, from the two Iref (...)
Hello everyone. I need to design this circuit for a full flash ADC 4 GS/s in 65nm cmos. There are some rules to do that? for example, how can I choose W, I bias and Rload for this circuit? please, I need a big help. circuit:
I have designed a LNA circuit in RFIC with charted RF cmos 0.18um process. The LNA's measured current and bias voltage agree with its simulated ones. Also, the LNA's input and output port have been matched well with VSWR<2 at 1.55GHz. However, the LNA's gain at 1.55GHz is only 5dB, far lower than the simulated vaule-15dB. Anyone can (...)
Hi, Id (M8 ) = Id(M9a) + Id(M9b) so vbias = Vgs value which gives Id(M8 ) considering the effects of Vds8 Practically u can find this Vgs value by plotting V-I curve for M8 you can refer to any books on Analog cmos design. Hope this helps. Thanks,
GIDL currents arises in the high electric field under the gate/drain overlap region. GIDL occurs at a low Vg and high Vd bias and generates carriers into the substrate and drain from surface traps or badn-to-band tunneling, (taken from: Kaushik Roy :"Low Power cmos VLSI circuit Design")
Hello. I need to design a substrate charge pump to generate a negative substrate bias. The picture shows a simple substrate pump basic cell proposed in the Baker Li "cmos circuit Design, Layout and anyone tell me any formulas to design this circuit
Hi Guys For most of the voltage bias points, they connect to the gate of cmos, so drive infinite load, but how to set the driving DC point. For example, you have a battery of 2V, your circuit working voltage is 1.2V@2mW, so how to set the DC voltage in this case. The only way I can think is to make the bias current big (...)
The rectifier block uses a cascaded Dickson voltage multiplier circuit with multiple cascaded sections in order to convert the extremely low input voltage up to a potential suffi cient for operating cmos circuits. The bulk terminals of the PMOS transistors were tied to the gate and drain terminals (back-bias) to reduce the (...)
for a certain bias current and to have a certain (vgs-vt) PMOS transistor width should be more than 3 times NMOS that causes 3 times more parasitic capacitance
Calm down. It's not a big deal. You circuit appears to be a self-biased diff amp. it's basically a stack of the PMOS input diff pair with NMOS input. Due to self-bias, the top and bottom current biasing xtor will be pushed into triode region which is OK. Having said that, I usually ratioed the sizes of the PMOS (...)
in analog design , u don't use the minimum channel lenght ,specially to design bias network and bandgap reffernce , most of the time , the length is about 5 times the minimum ad this make the transistor awy for short channel effects , and it is closely square law khouly
1. Design start from the specifications: convertion gain, noise figure, IP3, current consumption, ... 2. Select mixer circuit type: passive (diode,...), active (Gillbert cell, ...), single balanced, double balanced, ... 3. circuit design: cmos, BJT, ... DC: bias, current, ... AC: gain, NF, IP3, ... This is my (...)
In IC, without L, & useing low voltage process how to get this bias?
For calculating the output resistance, all inputs and DC bias sources are deactivated (replaced by short circuit if voltages ).This would cause a short between the gate and source of M1 (at small signal analysis) so it would be replaced by rds1 .For M2 both its gate and bulk are connected to ground so the upper 2 current sources can be considered a
To improve Class B to Class AB, bias the input of the base-emitter junction of each transistor using a PN diode to eliminate the cross-over distortions of Class B amplifier.
why do we use current mirrors for biasing instead of dc voltages? what will happen if we use dc voltages for biasing
I think the bipolar is current driver circuit,if you directly use CLK driver the bias, there are big current.But IF you use cmos ,for its none gate current,so you can driver the bias .
A sets the DC bias of M2 M5 for B.
I really doubt your comment on better power supply regulation in sub-threshold region. Since, power supply noise rejection mainly depends on the output impedence of the MOSFET, and the output impedence is independent of the operating region and depends only on the bias current. Sub-threshold or Weak inversion (W.I) operation is widely used in pl
What is the purpose of R1? 4000 series logic incorporates two mos transistors (one p-channel and one n-channel) connected in complementary fashion to function as an inverter. Because of the symmetry of these two transistors, appropriate negative feedback around the complementary pair will cause the pair to self bias itself to approximately
You could do it as suggested by using Depletion mode NMOS. BUt using normal NMOS in a cmos process, I donot think it can be done. For example: think of a NMOS current source for a PMOS differential pair. Also think of a constant -gm circuit , for the lower NMOS diode what would be its VGS and hence the vdsat. And if this is used to bias (...)
If you don't mind a momentary startup glitch, you could use a DC blocking capacitor, and bias the right side to 2.4v with resistors.
Guys, Why when we do a small signal analysis for a transistor circuit, we ac ground any bias voltages and also why when we measure the input or output impedance (let say for a common source amplifier), we usually short the output when to find the input impedance and vise versa. Thanks, Anachip
All, I need help me in testbench for CMRR calculation for an op-amp. I shorted the input with DC bias and gave common AC. Until certain freq the CM gain (Acm) is in fraction (output is less than input). From the definition of CMRR = 20log (Adiff/Acm), which is 20log Adiff - 20 log Acm = +ve value - (-ve value) = big +ve value seems unrealisti
You can find a lots of papers on that topic from IEEExplorer. Some of the techniques used including bulk-bias transistors, current bulk-driven transistors, level-shifting etc.
I use calibre PEX extracting parasitic paramerter including resister and capacitor, But OTA bias voltage have 100mv offset when using hspice simulating it. The OTA is cmos circuits. bias voltage drives the gate of mos. Please tell me why.
I recommend you going to the basis!!!! Try to understand what you do!!! Please read Cargo Cult Science by Richard Feynman and this would help you to understand what it is supposed to do a scientis/engineer. Your amplifier is nonsense!! Your transistors are in extreme strong inversion. Never bias tail current source with a voltage. Just copy t
Q2. Total bias current in folded cascode case is required higher than in simple cascode stage to achieve same performance. why???
A temperature sensor with about 8 bits resolution digital outputs is needed. A circuit as simple as possible is appreciated. For example,chopper amp may be avoided in a PTAT bias generator if necessary. Thanks a lot!
Thanks while simulating it in the spice, some of the transistors are going in to linear region. Is there any commands in spice to varry the bias voltages for making all transistors in the saturation region!!!
i'm going to design a bias circuit which will output 2 bias current. The 2 current should meet: sqrt(I1)+sqrt(I2)=constant Could anyone help me to find some good structure? Thanks
what is the LinMOS?It is proprietary of Texas Instruments. They say it offers extremely high input impedance and low input bias and offset currents. They say a lot of features associated with bipolar technology are available with Lincmos operational amplifiers without the power penalties of traditional bipolar devices. S
that's not how it's done, but can be used sometimes. real bias networks in IC's kill the gate voltage to shut off the bias network. for a set of pmos mirrors, you'd add a pmos between vdd and the gate connections. now when you turn this pmos on, it pulls the gates of all your mirrors to vdd and shuts off your bias currents. a (...)