[D] package and assembly info

If you are looking for a company to package and assembly the chip, you can check the following website and contact these companies. Some companies provide package components but some don’t, so you have to buy yourself and deliver components to them.


MOSIS also provided some package manual at here. The bondwire model with inductance, resistance and capacitance is also attached.

So for the future simulation, if you want to get more real model, you have search the bondwire parasitic parameters based on the chip package type.

For chip package and assembly work, we have to search which type of package is fitful for your chip. Like for image sensor chip, we have to use the package with open cavity. The size of opening you also have to consider.

How many leads does the chip need? What about the die size? Which type of the bond wire? What about the bond type? And what about the package sealing preference? What about the die pad width & pitch? What about the wireboding diagram?

All these considerations you have to make before sending the die to companies.


If you want to know the introduction about different package types, please read the page on wikipedia.

I also recommend the article posted on sparkfun. It introduces about the IC and package information you need to know.



Package Types:

PGA: PIN Grid Array

BGA: BALL Grid Array

DIP: Dual in-line package (CERDIP, PDIP, SPDIP, SDIP)

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[D]relation between frame rate and sampling frequency

The sampling frequency is the number of cycles of the measured clock in one second with a unit Herz(Hz).

fs=1/T=1/(one period of the measured clock)

In the imaging sensor chip, frame rate is the rate at which an imaging device displays an consecutive images called frames. It is to measure the number of frames in one second the imaging chip could offer in a unit of fps.

As we known, the ADC has been used in the output interface to generate the bit to convert the analog signal captured by the each pixel. So the sampling frequency of the ADC has a relation of frame rate.

fs=(number of pixels in imaging chip) x (frame rate).

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[D] packaging info from ADI

Designing PCB should be taken careful preparation and planning. Package size, pitch and spacing are critical to ensure that your board design is accurate and will function correctly.

I recommend to search and find materials from Packaging, Quality, Symbols& Footprints written by ADI

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[D]logic optimization

For logic optimization, I recommend the software “logic Friday“.

It can help you save more time.

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VISIO trick: How to use pencil,line,arc to draw any shapes

VISIO is a powerful tool. For engineers, we always have to draw some figures to explain our circuits and designs. It is beneficial for you to be good at the tool.

Please read the article from microsoft to understand the topic.


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[D]charge, current, capacitor, voltage

When using a constant current to charge the capacitor, the charging voltage on the capacitor will follow the equation:


If we know the input in terms of number of electrons, we can use the equation to calculate the current:

Formula :
Number of electrons ( N ) = ( I x t ) / e
I is the reading of ammeter.
t is the amount of time the current flows.
e is the charge of one electron.
e = 1.6 x 10 ^ ( -19 )


I = 0.50 A
t = 2.0 min = 1.2×102 s
I=q/t, so the magnitude of the charge is
q = It = (0.50A)(1.2×102 s) = (0.50C/s)(1.2×102 s) = 60 C
Solving for number of electrons from
q = ne
n = q/e = 60 C/1.6×10-19 C/electrons = 3.8×1020 electrons

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[D] interview question: DFF setup/hold time

I recommend a good article talking about the setup time and hold time issue in transistor level.

The setup time is determined by one TG and two inverters;

The hold time is determined by the first TG, because there is a time consuming for turning on/off the TG.

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