Social Security + Medicare benefits:

If you have worked in USA, you know it hurts to pay Social Security (SS) + medicare taxes, that average about 7.5% of your wages. It's 6.2% (upto a certain threshold) for your SS taxes and 1.45% for medicare taxes (with no threshold, i.e you are taxed on your whole salary).

For Social security + medicare taxes that you pay during your working career, it's good news if you make it past 62. You start getting some of the SS taxes back as monthly paycheck. If you live long enough and your wages weren't high to start with, then you would get a lot more than what you paid into SS taxes.Same goes for Medicare taxes, where a major portion of your medical bills are paid by medicare, with a minimal amount coming out of your pocket.

It's not only the retirement benefit that SS office pays, but it also pays out disability benefits. This is particularly helpful, if you get disabled or pass away. You or your family can collect disability benefits so that they can at least survive, even if you or your spouse can't do a paying job. It also pays medicare benefits, and usually both SS + Medicare are clubbed together as SS benefits.

The link to official SS govt site is: https://www.ssa.gov/

Here you can open an account and track your SS benefits that would get in retirement or on getting disabled. Make sure everything over here is accurate wrt SS taxes and earnings reported. If you find a discrepancy, contact the SS office. They also send you a yearly statement, though I haven't been receiving them for a while (maybe they stopped sending)?

SSA Trust:

All money that we pay in as SS taxes get put into a fund, and then money is paid out of it as benefits. In the past, more money was collected as taxes, and less money was paid out, resulting in accumulation of money in this trust fund. This Trust fund is divided into following sections:

  1. OASDI (Old-Age and Survivors and Disablity Insurance) Trust fund for Retirement + Disability benefits. Total of 12.4% (10.6%+1.8%) of payroll taxes are deducted for this. It's separated into 2 parts:
    1. OASI (Old-Age and Survivors Insurance) Trust Fund: This is what pays monthly retirement (old age) checks to millions of Americans. 10.6% of pyaroll taxes are deducted for this.
    2. DI (Disability Insurance) Trust Fund: This is what pays disability benefits when you become disabled. 1.8% of pyaroll taxes are deducted for this.
  2. Medicare Trust Fund for paying medical benefits. Total of 2.9% of payroll taxes are deducted for this. It's separated into 2 parts: 
    1. HI (Hospital Insurance) Trust Fund: This is what pays for primary medicare. Payroll taxes of 2.9% are deducted for this.
    2. SMI (Supplementary Medical Insurance) Trust Fund: This is what pays for any additional medicare benefits (Part B and Part D). The funds for this doesn't come from payroll taxes but instead from govt funding and premiums paid by members who enroll in this.

2023 Report of SS Funds (published in 2024) => https://www.ssa.gov/OACT/TRSUM/tr24summary.pdf

As seen in this report, OASDI collected payroll taxes of $1T (OASI) and $0.2T (DI). Medicare collected $0.4T (HI) and $0.6T (SMI, where govt contribution=0.45T and premiums=$0.15T). Looking at payroll taxes collected for HI, we get a ballpark of $10T of total payroll income taxed. About 180M people in US pay into this fund as payroll taxes. All in all, $2.35T were collected as tax/interest to be put into the SS trust

OASDI/Medicare benefits paid out almost same as what was collected as payroll taxes + tax/interest collected. Benefits paid out for OASDI were $1.2T (OASI) and $0.2T(DI). Benefits paid out for Medicare were $0.4T (HI) and $0.6T(SMI). However after accounted for other administrative expenses, the total money going out is projected to be about $0.2T more for OASDI fund, and $0.05T more for HI fund. 58M people received OASI benefits and 8M received DI benefits, amounting to 67M people receiving OASDI benefits. In addition, 67M people received Medicare benefits (mostly the same people who received OASDI benefits). All in all, $2.5T were paid out as benefits/expenses out of the SS trust

At end of 2023, OASI reserves were $2.6T, DI were $0.2T, HI and SMI were each $0.2T. Since money paid out is more than what is coming in, reserves started getting depleted from 2021 onwards. OASDI funds are getting depleted by $0.1T/yr and will get completely depleted by 2034.  Same with HI funds which will deplete in 2035. After that, money coming in will only be able to pay 80-90% of benefits, unless there's  change in law or more money starts coming in via higher SS taxes on payroll.

Maximum taxable Wages for SS:

OASDI Taxes:

As long as you are in the workforce, you pay SS taxes. If you are employed by someone else, you pay 6.2% of SS taxes, and your employer pays 6.2% of SS taxes on your W2 wages. However, if you are self employed, you pay full 12.4% of SS taxes. This 6.2% or 12.4% only applies to first $100K-$200K or so of your wages, any wages after that aren't hit with the SS tax. Every year, a threshold is set for max wages that will be subject to SS taxes. It's adjusted every year by wage inflation rate. 

The history of max taxable wages is here: https://www.ssa.gov/policy/docs/policybriefs/pb2011-02.html#:~:text=Social%20Security%27s%20tax%20max%20has%20evolved%20throughout%20the,future%20benefit%20adequacy%20for%20middle%20and%20higher%20earners.

For year 1970, max wages subject to SS taxes was about $8K, while for 2000, it was $78K, implying a raise of about 8%/year. From 2000 to 2022, it went from $78K to $147K, which is lot slower rise of 3%/year. The chart in the link above also shows that only 6% of the people pay the max SS tax, as their wages go over the SS max wage limit. This 6% number has remained constant over last 15 years or so. So, it looks like wage inflation being priced in the formula for max SS wages is working as it ought to be. So, if you are paying the max SS tax every year, you can take console in the fact that you are in the top 6% of income earners (based solely on wages, and NOT on other income as dividend, capital gain, etc, as SS taxes don't apply to those). With a workforce of 160M people in USA, this works out to about 10M people who have wages over > $150K for year 2022. The number of people having income of over  $150K in 2022 may be lot more than 10M, as a large number of employed or unemployed people may have passive income as renting, dividends, capital gains, etc. People in top 1% have most of their income from assets and NOT wages. So, they may not be even in this 6% of people.

Medicare taxes:

You do have to pay medicare taxes too on all of your W2 wages. It has no max threshold. If you are employed by someone else, you pay 1.45% of Medicare taxes, and your employer pays 1.45% of SS taxes on your W2 wages. However, if you are self employed, you pay full 2.9% of SS taxes. If your wages are above a certain threshold, you pay an additional tax on top of this tax. So, you get penalized for Medicare (as opposed to OASDI taxes, where you had a max cap on taxes)

SS payout:

Now the important part - how much do you get in SS benefits once you retire or get disabled. Let's look at the retirement benefits.

SS benefits are calculated based on your 35 highest-earning years in the workforce, and are adjusted for inflation. If you don't have 35 years of earnings, zeros are averaged in for the years you didn't work at a job in which you paid into Social Security. The proportion of your income that is replaced by Social Security varies based on how much you earn. Consider a worker who turns 62 in 2011. To calculate his benefit, the first $749 of his average monthly earnings is multiplied by 90 percent, the next $3,768 by 32 percent, and the remainder by 15 percent. The sum of these three amounts equals his initial monthly payment amount. Workers also have cost-of-living increases added to their benefit beginning at age 62, even if they don't begin to receive benefits until a later year.

If you have worked for at least 10 years in USA with earning of > $5K/year, you will have accumulated 40 points (4 points per year is earned for taxable wages of $4K/yr). Having 40 points entitles you as well as your spouse/kids to get SS benefits. You don't have to work consecutively. As long as it's 10 years of wages, you will be eligible, no matter what your citizenship or visa status is. As an ex, if an Indian worked in USA for 10 years on H1B visa, and then goes back to India and settles in India thereafter, he would still be eligible for monthly paycheck once he reaches age 62. SS tax is your money, which you are eligible to get back in retirement. Since the money from SS fund is distributed in a social way to help poor people more than rich people, rich people get paid less than what they paid in, while poor people get paid more than what they paid in.

In June 2011, the average Social Security benefit was $1,180.80 per month. The maximum possible benefit for a worker retiring at age 66 in 2011 is $2,366. But to get this amount, the worker would need to earn the maximum taxable amount, currently $106,800, each year after age 21 for at least 35 years (as of 2011).

Here's the calculator on SS.gov website to show your retirement benefits, customized to your earnings: https://www.ssa.gov/benefits/retirement/planner/AnypiaApplet.html

Other quick calculator to give you a ballpark is here: https://www.ssa.gov/OACT/quickcalc/

As per above calculator, if you were born in 1960, and are retiring in 2022, and paid max SS tax for 35 years of your life, you would get $2K/month (in 2022 dollars). Your spouse will get the same amount if she also has same credentials as yours. Even if the spouse never worked, he/she would still be eligible for half of the SS benefits of her working partner. So, in this case, if the working partner got $2K/month in retirement, then non working partner would collect $1K/month if retiring in 2022 (i.e over 62 yrs of age). That would net a SS income of $3K/month.

However, if you earned only $5K/yr for your entire working life, you would get only $170/month. If you earned $50K/year (which is median wages), you would get about $1K/month in SS paycheck.

You may see that the SS paycheck is not enough to cover rent, not to mention food, utilities, transportation, etc. In states like Texas, it may not be enough to even cover the property tax on your house (even though you owe no mortagage and it's paid off). That's why you need other source of income such as 401K or your personal savings to survive in retirement. SS paycheck is just going to be enough so that you don't starve, though you might still be homeless.

Taxes on SS benefits:

Here comes the nail in the coffin - you would have to again pay federal income taxes on any SS paychecks that you receive in retirement or during your disability. It depends on your other income during retirement that eventually decides how much of your SS benefits would be taxed and at what rate.

Taxes on SS benefits are on this link: https://www.ssa.gov/benefits/retirement/planner/taxes.html

Most likely, 85% of SS paycheck is taxable assuming total income of > $50K in retirement.

 

 

 

USA Visa:

If you want to enter USA and are not a citizen of this country, you will need to apply for a Visa in order to enter the country. USA Visa fall under 2 broad categories:

  • Non immigrant Visa: This is the category of visa for people who are coming to USA on temporary basis and don't intend to settle in USA. Usually when you are applying for a Visa for a job, education, visit for your parents, it's usually non-immigrant Visa. The maximum amount of time you can stay in the U.S. per year is 6 months, depending on why you entered the U.S., to begin with. These are 3 most popular Visa:
    • Work Visa: This Visa is needed if you want to work in USA. You can't directly apply for this Visa. It's your US employer who must file a petition for you with the USCIS, asking to grant you a Visa.  Usually when you complete your education in USA, you would need to apply for a work Visa to start working for an employer. Or your US emplyer can apply on your behalf to hire you directly from other country. Once the Visa is approved, you may start working. The criteria for this Visa is pretty restrictive. There are 2 most widely used Visa within Work Visa:
      • H1B/H1B1: H1B is the most widely used Visa to allow you to work in USA. Your non working spouse may get a dependent Visa based on your H1B Visa.
      • L1A/L1B: L1A and L1B visas are meant for individuals who transfer within a multinational company. So, for ex you are working for TCS in India, and company wants to transfer you to USA, they may apply for either H1B Visa or a L1 Visa. In the past, H1B Visa were used in such situations, but increasing L1 Visa are being used.
    • Student Visa: Student visas are made for individuals who want to study in the U.S. These are issued by the US embassy in your country when you apply to a USA university and get accepted. Then you appear for an interview in US consulate.
      • The F-1 visa is meant for full-time students going to an accredited educational institution. People with this visa type can only get a job on-campus. F-2 visas are available for children or spouses of F-1 visa holders.
    • Visitor Visa: Someone who wishes to enter the U.S. for tourism reasons or temporary business will need a visitor visa. Unless your home country is covered by the Visa Waiver program, you will have to get a B-1 or B-2 visa. Your documents for the application must be sent to the DHS. These documents should explain your travel reasons and your trip itinerary. The validity of the visa is usually between 3 months and 10 years, depending on where you live. Usually, people can stay in the U.S. for 6 months annually.
      • B1/B2 Visa: B1 Visa is for Business travellers while B2 Visa is for tourists. Generally, both of these Visa are issued under category "B1/B2" Visa (that is what gets stamped on your Visa)
  • Immigrant Visa: This category of Visa is for people who want to settle in USA permanently. An example of Immigrant Visa is "Geen Card". We'll talk about these in a separate section.

Getting Immigrant Visa:

Typical route for people from India to get an Immigrant Visa (aka Green card) is outlined below. Usually these are the 2 paths people choose:

  1. Apply to a US University. On acceptance, get a F-1 Visa, then come to USA, study for few years for MS/Ph.D. Then apply to a US Company for a job. On getting the job, they apply for H1B Visa on your behalf. As soon as you join the company, ask the company to file an application for "Green Card" for you. There's a long waiting line for Green Card processing. There are 3 categories of applying: EB-1 is high priority and you get a green card within a year. EB-2 and EB-3 are low priority and takes over 10 years to get a green card.
  2. Work for a company in India. That company send you to USA either on a H1B Visa or a L1 Visa. As soon as you land in USA, you ask your company to file an application for "Green Card" for you. If you came on L1 Visa, you file under EB-1, while if you came on H!B Visa, you file under EB-2 or E-3 category. If you want to get your green card soon, you should try to come on L1 Visa.

Once you get your Green card, you have to wait for 5 years before you can apply for citizenship. Once you get your citizenship, apply for a USA Passport. There is a separate section that deals with applying for USA passport.

 

Applying for Visitor Visa for your parents or relatives:

This is a link for US Embassy in India that issues USA Visa for Indian nationals: https://in.usembassy.gov/visas/

This pdf file on above link explains the steps: https://in.usembassy.gov/wp-content/uploads/sites/71/1.

Here are the steps (as of April, 2022):

  1. Fill out the application form at: https://ceac.state.gov/ceac
    • For Visitor Visa, fill out the DS-160 form: DS-160, Online Nonimmigrant Visa Application
    • It's a lengthy form, and needs to be filled for each applicant separately. Some of the entries to be filled may not be readily available to you, so use your best guess for those.
    • If you are planning for both of your parents to visit you, you should fill the form 2 times, and save a pdf copy of the final submitted form
  2. Now, go to usa travel docs website, create a user account (only one user account needed for both your parents). www.ustraveldocs.com
    • choose "India" as your country.
    • choose "non immigrant visa", and then on next screen, make your user account (if you don't have one already)
    • Once you log into your account, on left side menu, it will show "New application / schedule appointment". Click that and start filling in information for onw of your parents. At the end of the form, it will ask, if you want to add any more family members. Go ahead and add your parents with pertaining details.
    • You have to enter "confirmation number" from DS-160 form for both of your parents or other applicants. This is how this account gets linked to proper applicants.
  3. Once step 2 is almost complete, you will see instructions on how to deposit the application fee. As of 2022, it's $160 per applicant. You have to pay it in INR, and may only use Indian banks for this. So, either you need to have an online bank account with a bank in India (it may be anyone's account, not necessarily belonging to you or your relatives), or you need to pay in cash at one of the bank locations mentioned (Axis or Citi bank)
  4. Once the payment has been made , you have to finish step 2. You may return to http://portal.ustraveldocs.com/ and enter the bank reference number provided in your bank receipt (not the advice slip).
  5. On the same link, you will see option for Visa interview scheduling. Schedule two separate appointments online.
    • One for a visa interview at the U.S. Embassy or Consulate.
    • Another for biometrics collection at an Visa Application Center (VAC)
    • For people who are renewing their Visa, you may qualify for "Interview waiver" which waives the requirement to appear in person for the interview. You have to still submit your passport, and other forms to consulate. You will still get your appointment date and time. On that date and time, someone will need to go and submit your documents (it can be anyone, doesn't need to be applicant). Consulate will accept these documents and process it in the next few days. Renewed Visa + passport may be returned back you by mail, or you may pick up in person at the consulate (whichever you selected at time of filling the application). Mail is easier, otherwise you will again need to send someone to Consulate to collect the passport + Visa.

A this point, you are done with "visitor visa" for your parents or other relatives. Congrats !!

Mobile communication:

Mobile communication refers to the tech used is cell phones to communicate with each other. Since this tech came into existence in 1980, it has gained immense popularity. It has undergone various generations with improving speeds.

Generations:

In the field of mobile communications, a "generation" generally refers to a change in the fundamental nature of the service, non-backwards-compatible transmission technology, higher peak bit rates, new frequency bands, wider channel frequency bandwidth in Hertz, and higher capacity for many simultaneous data transfers.

New mobile generations have appeared about every ten years since the one in 1981. Here's the wiki link: https://en.wikipedia.org/wiki/List_of_mobile_phone_generations

  • 1G: 1st generation, analog. Introduced in 1981. Not used anymore.
  • 2G: 2nd generation, digital. Introduced in 1992. 2G systems are significantly more efficient on the spectrum allowing for far greater cell phone penetration levels. 2G introduced data services for mobile, starting with SMS (Short Message Service) plain text-based messages, picture messages and MMS (Multimedia Message Service). GSM and IS-95 were the two most prevalent 2G mobile communication technologies in 2007. Even today as of 2022, 2G is still being used as a fallback service on all modern phones, as well as in rural areas.
    • GSM (Global System for Mobile Communications): This was more popular and had 80-85% market share. GSM uses TDMA (Time division multiple access) and FDMA (Frequency division multiple access) for user and cell separation. GSM phones used a SIM card, and so could be used internationally.
    • IS-95 (Interim Standard 95): This was the first ever CDMA-based digital cellular technology. It was developed by Qualcomm. It's proprietery name was CDMAone. This was less popular and had 10-15% market share. IS-95 uses CDMA (code division multiple access) for user and cell separation. IS-95 phones are generally unable to roam internationally, and are tied to a specific provider.
  • 3G: 3rd generation, introduced in 2001. multi-media support, spread spectrum transmission and a minimum peak bit rate of 144 kbit/s. Later 3G releases allowed max speed of Mbits, which made video calls, mobile internet access, mobile modems for laptops, etc possible. Most prevalent 3G standards are UMTS and CDMA2000 which are upgrades from GSM and IS-95 used in 2G. 3G is mostly dead, as newer generations use 2G as a fall back standard, instead of 3G.
    • UMTS (Universal Mobile Telecommunications System): Used in regions predominated by GSM 2G system infrastructure. The cell phones are typically UMTS and GSM hybrids. UMTS is a full revision from GSM in terms of encoding methods and hardware, although some GSM sites can be retrofitted to broadcast in the UMTS/W-CDMA format. W-CDMA is the most common deployment, commonly operated on the 2,100 MHz band. A few others use the 850, 900, and 1,900 MHz bands.
    • CDMA2000: This is used especially in North America and South Korea, sharing infrastructure with the IS-95 2G standard. The cell phones are typically CDMA2000 and IS-95 hybrids.
    • EDGE (Enhanced_Data_rates_for_GSM_Evolution): It's revision to the older 2G GSM based transmission methods, which utilizes the same switching nodes, base station sites, and frequencies as GPRS, but includes a new base station and cellphone RF circuits. It is based on the three times as efficient 8PSK modulation scheme as a supplement to the original GMSK modulation scheme. EDGE is still used extensively due to its ease of upgrade from existing 2G GSM infrastructure and cell phones.
  • 4G: 4th generation, introduced in 2011/2012, followed by "real" 4G, which refers to all-Internet protocol (IP) packet-switched networks giving mobile ultra-broadband (gigabit speed) access. 4G users get speeds of up to 100 Mbit/s, with Gbit/s speeds possible. Common standards supported are:
    • Mobile WiMAX: WiMAX added support for mobility, and thus came mobile WiMAX to be used for celular transmission. This is not widely used??
    • LTE (Long Term Evolution): It's commonly marketed as 4G-LTE. LTE is based on the GSM and UMTS standards. It improves on those standards' capacity and speed by using a different radio interface and core network improvements. LTE is the upgrade path for carriers with both GSM/UMTS networks and CDMA2000 networks. Because LTE freq and bands differ from country to country, only multi-band phones can use LTE in all countries where it is supported. LTE supports scalable carrier bandwidths, from 1.4 MHz to 20 MHz and supports both FDD (Freq division duplexing) and TDD (time division duplexing).
  • 5G: 5th generation, introduced in 2021. Also known as 5G-NR (5G new radio). It supports data rates of several tens of megabits per second (Mbit/s) to tens of thousands of users, with speeds surpassing 10's of Gbit/s. 5G transmission is supported only on phones that have 5G chip on them, which are newer phones introduced in 2020. All these 5G phones also support 4G, since 5G isn't supported widely (as 5G transmission is expensive with all new equipment, etc needed). T-mobile USA was the 1st company in the world to launch a commercially available 5G NR Standalone network (others used 4G LTE network initially). The higher speeds in 5G are achieved partly by using additional higher-frequency radio waves, but they have a shorter useful physical range. 5G can be implemented in low, medium and high bands.
    • Low band: Low-band 5G uses a similar frequency range to 4G cellphones, 600–900 MHz, giving download speeds a little higher than 4G (25-250MBits/s). Low-band cell towers have a range and coverage area similar to 4G towers.
    • Mid band: Mid-band 5G uses microwaves of 1.7–4.7 GHz, allowing speeds of 100–900 Mbit/s, with each cell tower providing service up to several kilometers in radius. 
    • High band: High-band 5G uses frequencies of 24–47 GHz, near the bottom of the millimeter wave (mmWave) band, although higher frequencies may be used in the future. It often achieves download speeds in the Gbit/s range, comparable to cable internet. However, mmWave have a more limited range, requiring many small cells. They can be impeded or blocked by materials in walls or windows.

That's all the generations for cellular communication until new ones come up.

 

Wireless basics:

This section will go over the basics of how wireless communication works. We will also look at wireless chipdesign, antenna design, and also at various standards involved in wireless.

Cell phone standards:

 

VCLP:

VC is Verification compiler platform from Synopsys. It is a platform that has a suite of verification tools that can interoperate with each other. VCLP is a tool from VC that verifies designs that use voltage control based techniques for pwr mgmt. It's a multi-voltage, static low power rule checker. IT verifies the power intent of design captured in IEEE 1801 UPF, and later verifies the implemented power intent in netlist.

These are the checks done by VCLP:

  • Power Intent Consistency Checks =>Performs syntax and semantic checks on the UPF that help validate the consistency of the UPF before starting with the implementation. It's done at RTL level.
  • Signal Corruption Checks => Detects the violating power architecture at the gate-level netlist.
  • Structural Checks => Validates insertion and connection of special cells used in low power design such as isolation cells, power switches, level shifters, retention registers, and always-on cells through out the
    implementation flow.
  • Power and Ground (PG) Checks => Check the PG consistency against the UPF specification for power network routing on physical netlists.
  • Functional Checks => Validates the correct functionality of isolation cells and power switches.

 

VCLP flow:

Bringing up VC Static Shell (vcst in short):

Add path to vc_static_shell installation area to your $PATH var (or provide the full path). Path is usually something like /tools/synopsys/vcst/bin/vc_static_shell
% /tools/synopsys/vcst/bin/vc_static_shell => This brings up vc_static_shell (or just type vc_static_shell if path is already added to your env var $PATH)

vc_static_shell -help => shows all options available with vc_static_shell

vc_static_shell -gui -output_log_file vclp.log -no_color -full64 => -gui brings up the gui instead of cmd line. console output is captured in given log file by using option -output_log_file (or in short, use -o). -no_color starts tool in non-color mode. -full64 or -mode64 starts tool in 64 bit mode (-mode32 starts tool in 32bit mode)

2 ways to run vc_static_shell:

  • batch mode: Here, we specify the script to run, and vc_static_shell runs the tcl script and quits the shell on completion. cmd: vc_static_shell -f my_vcst.tcl -batch
  • Interactive mode: Here, we run in interactive mode, so the shell is brought up, where we can run any cmds we like. cmd: vc_static_shell -f my_vcst.tcl 

vc_static_shell -session my_path/my_session <other_cmds> => Once vclp is run, it creates a default session named "vcst" in dir called "vcst_rtdb" (vcst_rtdb/vcst). To change this default, we provide option "-session". Here, in current dir/my_path, a dir named "my_session_rtdb" is created instead of vcst_rtdb", but session name is still vcst (my_path/my_session_rtdb/vcst). To change session name, we have to fork the existing session and save the forked session with a new name by using cmd "save_session my_saved_session" from within vcst cmd shell, before exiting. Then next time, we can use that saved session to restore.

 Setup file:

Similar to other synopsys tools, we have a setup file called .synopsys_vcst.setup that is used the env for VCLP runs. It may be put in installation dir, home dir or run dir or in all 3 places. Priority is based on this order hwere run dir has highest precedence.

 

3 levels of Low Power checks:

  • RTL level: Here VCLP checks for UPF consistency and signal corruption checks. UPF checks ensure that UPF is clean, and design conforms to all iso/levl shifter rules for all power modes.
    • Here we use VCLP cmd: check_lp -stage upf
  • Netlist level (synthesized design): Here VCLP checks for signal corruption, as well as structural and functional checks. Design instances need to be consistent with UPF, as well as the design is both structurally and functionally correct.
    • Here we use VCLP cmd: check_lp -stage design
  • Power ground connected netlist: Here VCLP checks for power ground pin connectivity in post layout design to be consistent with UPF.
    • Here we use VCLP cmd: check_lp -stage pg

Checks to enable/disable and their severity:

VC LP provides a large number of low power checks. All these checks have a message tags and a predefined reporting format. Based on collective user feedback, by default, VC LP has certain checks enabled and
certain checks disabled. Also, the severity is predefined for each tag of a violation.
VC LP provides the flexibility for you to pick and choose which checks are relevant for your design. You can change the default enable/disable status of check and also change the severity of a check using the configure_lp_tag cmd.

ex: configure_lp_tag -tag ISO_INST_MISSING -severity warning
ex: configure_lp_tag -disable -tag RET_INST_MISSING -disable -goal g1

signoff check:

configure_lp_electrical => This cmd is used to check a limited number of checks during final signoff. We are not looking for UPF correctness at signoff (since that should be checked much earlier in deesign process and already fixed by now), but rather at electrical correctness.  We run this cmd, then run check_lp with any option above, and then run report_lp. There are 40-50 signoff_tags (like ISO_INST_MISSING, LS_INST_INCORRECT, PG_PIN_UNCONN etc) included in configure_lp_electrical.

Inputs to VCLP:

  • RTL(verilog, VHDL, SV), netlist or post layout netlist
  • Liberty files (.lib or .db) for resolving, elaborating the design, recognizing special cells and annotating power connections. Liberty files needed for RTL designs only if RTL has pre-instantiated LP cells as ISO, LS, macro, pads, etc. For netlists, liberty files are necessary. Liberty files need to be low pwr ready, that is, they have pg pins defined and have all low power specific attributes as relevant.
  • power intent specified in UPF file

Output from VCLP:

  • Log file: Log of what ran
  • Report file: error and warnings report for all violations related to low power static rule checks

cmds:

1. read design

read_file => Read in design source files, and link design in memory.

2. read pwr intent:

read_upf =>