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Hello all, I want to know if it's normal for std cell libraries to have their std cells with non-tied bulk transistors. I'm using Nangate 45nm library and found that transistors in std cells GDS have floating bulks while their schematics have bulks correctly connected. So how Nangate give out a cell library with cells that is not correctly conne
Which metal layer is used for standard cell pins? Will all the pins be M1 or will it always be M2 or will it be a combination of M1 and M2 or can it be a higher metal layer like M3??
Most standard IC's are built with a process that generates a parasitic substrate diode. This diode is normally reverse biased with the proper polarity of the applied supply voltages. As noted, a reverse polarity supply will forward bias this diode, thus the current will be limited only by the power supply current limit and/or the resistance in the
I believe, the purpose of separate vdd and vddIO pins is explained in the datasheet. In a short, connecting both to a common 3V3 supply is the standard case and should work for your application.
It mainly depends on your application. If you are doing a standard cell layout that sits in another block, it is better to use lower metals and preserve higher metals for other blocks routing. If you are laying out a single block and are sure that there is no top metal blockage, then it is good to go for higher metals for lower resistance. A go
Hello In few standard cells, bulk of PMOS and NMOS are usually given a seperate bulk Voltages ,unlike the normal shorting of bulk to vdd and VSS in PMOS and NMOS respectively. Why is it done so? And would the Bulk voltages be higher or lesser than the supply voltages? Please share any docs related to the same concept. Thanks BB
Hi, standard cells from fab are having global vdd and gnd. I wan to convert it into local pin limited to same digital gate. Can Anybody let me know how to solve it ?
You need to check a design manual for this process. The nominal vdd for 180nm is 1.8V but for some I/O devices a standard is 2.5, 3.3 or 5V. This 2v or 3v could also means threshold voltages.
I am trying to run LVS using a design I created in Encounter but am receiving a number of errors. I have used the >saveNetlist -excludeLeafCells -includePowerGround command to create a netlist which includes vdd and VSS just like the layout. My standard cells also include VBP and VBN pins which are not connected in the netlist. When I go
Hi, after running RTL Compiler I get a verilog netlist without vdd! and vss! ports. I think the reason is the .lib library that does not provide them for the standard cells. (but they are declared in .lef). Im not sure if this is a problem or not... When running Encounter after init_design I do the following: (Power pins are initialized by "se
Hi all. I am trying to do LVS using std. cells from foundry. I am using Cadence tools with Calibre LVS. I am currently using an inverter (with input and output pins) as a test case. 1. Anyone know how to handle inherited gnd/vdd in layout? I see them in the schematic netlist, but I dont know how to include them in the layout. Are there any s
I have claculated the Dynamic Power for standard cell in ELC(Encounter Library Characterizer) using Formula : Rise Power = Integ (Ivdd - Ilkg) *V - CV^2 By Deducting switching power from rise power In Spectre i have used the command : export real name1 = integ (trim (sig=I(vdd), from=t1 to=t2) -(I_leakage)
hi, I am developing a standard cell characterization. Now I am doing for I O cell characterization. How to calculate leakage current while doing for pad simulation. Thank you
Hi, "GLOBAL" is used in the netlist because your standard cells has pins to both "vdd!" & "VSS!". The tool is just regarding "vdd!" & "vddD" as separate nets (similarly with your grounds). I believe the issue is due to the tool thinking you're shorting unrelated nets. Is it intentionally in your design to connect the (...)
... better not connect the drain of NMOS with vdd directly in NMOS source follower and not connect the drain of PMOS with GND in PMOS source follower. IMHO there's no reason to avoid such a connection, after all it's the standard connection for source followers. For complementary source followers, howe
See below the guaranteed values for the HCMOS family. The standard CMOS 40xx devices should behave similarly. 77937 With VIH ≧ 2/3 * vdd and VIL ≦ 1/3 * vdd you're usually on the safe side.
In a standard CMOS process, Vss-0.3V...vdd+0.3V.
Hello, I got a std cell lib from some company, and I am confused by my hspice simulation results. For example, I include the libs and try to simulate the Intrinsic delay of the cell, however, the results from the simulation are always smaller than the documentation. I am pretty sure that I set the right vdd and temp conditions, so what cou
Hi yes they are, net name gnd! and pin gnd!, same for the vdd! globalNetConnect performed. In addtion, I also get the following warning message with sroute: (sroute performed before placement) Begin power routing ... **WARN: (ENCSR-1253): Net vdd! does not have standard cells to be routed. Please check net li
Dear Neyolight, NExt time give the whole story from end to end of this clock. {including colpitts osc and PIC vdd} standard CMOS inverters make great small signal amplifiers 3 stages of x10 gain = 1000, while UB or unbuffered versions are only x10, so your small signal sine wave can be easily squared up with a couple passive parts and use
Hi - I have a PDK in which I have all standard cells (inverters, nands,etc.) defned in one common .spi file. I have standardlib symbols and used them within my analogic schematic for simulation. I defined on the toplevel global vdd!, gnd!, and also used CDF (vdd netSet vdd!, and VSS netSet gnd!) to (...)
In a self powered deviced, VBUS must no be shorted to vdd. There should be at least diodes to isolate the local power supply from VBUS. The USB standard requests, that VBUS isn't driven from the device side, also D+ and D- must not be driven before VBUS is present. The said VBUS monitoring circuit is used to enable the USB interface.
I convert my synthesized veriolg code into spice netlist but i have a problem. Every Cell (subcircuit) has its own vdd and VSS net name, but i want to have the netlist which has unique supply name for power supply net name. This is a sample of output converted netlist: . . . XU9 PA n9 X1 vdd_dummy47 VSS_dummy48 NAND2_X1 XU8 PA n8 X1 V
Using SoCE after sometime. have an issue. I have a verilog netlist in which an SRAM module is instantiated. The power supply name of SRAM in the netlist & in SRAM LEF is ramvdd, ramgnd. For the standard cells, the power supply in LEF file is vdd! & gnd! Now while routing I need to connect for vdd! and (...)
Why is global routing for standard cells sometimes preferred in Metal 2 layer? Although higher metals have lesser resistance, could adding vias to go to upper layers increase parasitics?
I agree with the comment above but have couple comments: - if you use standard IO cells from fab/IP supplier, such set often contains the separate digital/analog IO cells. - if you use manufacturer's PDK it usually provides an ability to separate the different gnds. Generally it's a special layer to cover all gnd islands (may be except one of th
If you operate the processor on 2V supply, even the ?1V input signal should trigger. Use the standard input protection circuit between your sensor and the processor input: 50066 R1=1..10kΩ ; use Schottky or Germanium diodes for vdd+0.3V / GND-0.3V protection.
Hi, I did a schematic in s-edit and exported a tpr file. I import it to l-edit and do all the setup stuff. When I choose to run place & route I get errors like no ABUT port and unmatched (or something like that) vdd ports. So I found out that I had to have ports named ABUT drawn around the standard cells, so I drew them, and then fixed the V
Hi I have imported my digital design of standard cells into cadence ICFb tool as schematics. I want to run simulation on the schematics in ADE. How can I provide global power supply to the VCC,vdd pins of standard cells as these power pins are not visible in symbol of std cells in the schematics. Thanks
Corners determine the mean value, while monte-carlo gives the standard deviation. There are 3 main types of corners, mainly PVT as you mentioned, of which you can trim only for process corners. So an example of a corner is NMOS FAST, PMOS SLOW, vdd=vdd(nom)*0.9 and T=-40C. To get the worst corner, you will need up to 2^N, or 16 corner (...)
Hello , I am designing a pseudo diffamp with following specifications. -Operating frequency of input signal : 1.4Ghz -Supply - 1.1v -Input swing vref+/- 150mV -Vref - vdd/2 +/- 150mV Max Vt of pmos/nmos in our technology is ~400mV Currently i am doing it with folded cascode of standard pmos and standard nmos diffamp. Can you (...)
The datasheet of PIC18F4520 states: "standard devices with Enhanced Flash memory, designated with an "F" in the part number (such as PIC18F2420), accommodate an operating vdd range of 4.2V to 5.5V. Low-voltage parts, designated by "LF" (such as PIC18LF2420), function over an extended vdd range of 2.0V to 5.5V." I was unable to source t
Hi, what decides the height of the standard cell? Thanks, yaasi
You will never be able to really reach 1.8V swing at the output, but you can get quite close. A standard 2-stage opamp should do the trick..
The constant 1'b0 or 1'b1 in HDL is realized with a wire connecting to vdd or GND. That is fine until you consider the ESD issue where a gate of a MOS FET is connecting directly to the power supply or ground. That's where the tie on/off gates come in. They are usually provided by the standard cell library and synthesis tool can pick them up automat
I2C standard requires that spikes of 50 ns or shorter on SDL and SCL lines shall be suppressed. What kind of spike should I assume? Without any further details from the I2C spec, it seems that we have to design the circuit so that it supresses 50ns square wave swing between gnd to vdd (which I believe is the worst case). But it requires quite stron
I would imagine that you will be operating outside of the charaterised range of the libraries that you have - therefore, you can't rely 100% on the results you will get from digital tools. You can often ask a fab to characterise the standard cells in a new corner for you (with your specified vdd), although this will cost. If you can't afford that,
Hi, We need to design a RS485 line driver with a process allowing a vdd max of 5.5V. The RS485 standard sets possible common modes from -7V to +12V, that is 7V away of each supply rail 0V and 5V. Does anybody know how to cope with this common mode exceeding the SOA of the process? Other line driver standards have the same (...)
Pad is like isolators between internal of chip and external world. Pad is used because the internal ckt voltage is very low and many not meet the I/O standard(e.g external interface is LVCMOS /LVTTL but chip internally might be opeating at 1.32 vdd...) so pad is used to convert to this level(i.e. level shifter). Other then this pad are also used to
A standard forward biased power diode will act as a zener, should be around 5-600mv op. Just use as a zener, but other way round. Series resistor to suit circuit consumption.
Yes, they are all the same. They are all Plastic Dual inline package.(standard pcb mounts) The rest is just temperature requirements. For indoor use, just take the middle one. Hope this helps, Red
in popular standard IO cells libs such as tsmc/umc/smic/charter, etc. IO filler is already exist. just use them is ok.
Dear dude, Normally the PMOS should be 2 or 3 times bigger then nmos. both cant be equal. if it is equal the rise time and fall tme will not be the same. so the switching point will be not at 1/2 of vdd. of course the capacitacne will vary if u shift from one statndard library to other, because standard cell are technology depenedent, l
Hi, Can anyone tell me what is the voltage vdd used for a 65 nm analog standard cell library and transistors. Thanks.
Non wireless standard would give you this kind of spec for LNA
I'm reserching theory about Mvdd design but I don't have library for it. Plz tell me if you know about the characterizes of the standard cells in this. Thanks,
tapless, which can be used to control the well and substrate biasing. how to control the leakage power, does someone know any detail?
In the standard ESD circuit of my CMOS designkit there are two positive and negative supply voltages respectively---just vdd(pad) and vdd2(core), Vss1(pad) and Vss2(core). and it is also required that vdd(pad) and vdd2(core) should not be connected together , the same for Vss. I am quite confused about (...)
I use standard cells for AFC simulation in Spectre, but there is no response in the output. Since there is no inputs for vdd and VSS in the standard cells. i think maybe it's the reason that cells can't function properly. Please sb tell me if vdd and VSS are necessary for standard cells in Spectre and how (...)
I use standard cells for AFC simulation in Spectre, but there is no response in the output. Since there is no inputs for vdd and VSS in the standard cells. i think maybe it's the reason that cells can't function properly. Please sb tell me if vdd and VSS are necessary for standard cells in Spectre and how (...)