Instrumentation Viva Questions

  1. What are the Types of Op-Amps ?

    Broadly its categorized as BJT based op-amp, FET(JFET and MOSFET) based op-amps. Except this these are also categorized according to frequency range, power consumption and operating voltage range.

  2. Explain about ChemFET, ISFET and ENFET.

    View Wikipedia pages.

  3. What are the other types of FET ?

    HEMT, MESFET, MODFET, NOMFET, OFET, DEPFET, CNTFET, … see the page on FET on Wikipedia.

  4. What is IGBT ?

    Insulated Gate Bipolar Transistor.  It is a device for power control. It has a structure akin to a MOSFET coupled with a bipolar-like main conduction channel. These are commonly used for the 200-3000 V drain-to-source voltage range of operation. Power MOSFETs are still the device of choice for drain-to-source voltages of 1 to 200 V.

  5. Name of FET and CMOS Op-amps ?

    TL084, National Semiconductor LF series, LT1056,.


    LMCXXXX —-National


    ICLXXXX —–Intersil

    LTCXXX ——Linear Technology

    TLCXXX ——-Texas Instruments

    S/H IC names ?



  6. What is Charge Pump?
  7. What is Loseless resistor/ Switched capacitor ?
  8. What is low side and high side switching ?
  9. What is retriggerable monostable vibrator ?
  10. what is a gimmick capacitor ?

I2C interfacing-II

 I2C or Inter-Integrated Circuit / Two-wire interface is a Multi-Master Serial protocol invented by Philips used to attach low-speed peripherals to a motherboard. It uses two open-drain bidirectional data lines SCL, SDL respectively.

  • The master is initially in master transmit mode by sending a start bit followed by the 7-bit address of the slave it wishes to communicate with, which is finally followed by a single bit representing whether it wishes to write(0) to or read(1) from the slave.
  • If the slave exists on the bus then it will respond with an ACK bit (active low for acknowledged) for that address. The master then continues in either transmit or receive mode (according to the read/write bit it sent), and the slave continues in its complementary mode (receive or transmit, respectively).
  • The address and the data bytes are sent most significant bit first. The start bit is indicated by a high-to-low transition of SDA with SCL high; the stop bit is indicated by a low-to-high transition of SDA with SCL high.
  • If the master wishes to write to the slave then it repeatedly sends a byte with the slave sending an ACK bit. (In this situation, the master is in master transmit mode and the slave is in slave receive mode.)
  • If the master wishes to read from the slave then it repeatedly receives a byte from the slave, the master sending an ACK bit after every byte but the last one. (In this situation, the master is in master receive mode and the slave is in slave transmit mode.)
  • The master then ends transmission with a stop bit, or it may send another START bit if it wishes to retain control of the bus for another transfer (a “combined message”).

I²C defines three basic types of messages, each of which begins with a START and ends with a STOP:

  • Single message where a master writes data to a slave;
  • Single message where a master reads data from a slave;
  • Combined messages, where a master issues at least two reads and/or writes to one or more slaves.

In a combined message, each read or write begins with a START and the slave address. After the first START, these are also called repeated START bits; repeated START bits are not preceded by STOP bits, which is how slaves know the next transfer is part of the same message.


Example:Interfacing AD5934

This chip is communicated by i2c protocol supported by some commands defined by the chip vendor.

To read and write to the registers of the IC the chip provide a list of interface commands

Round Corner | Curved Corner DIV Cross Browser

These days I am trying to edit the site design to have a better look and provide easy access for users by a simple and good navigation menu. But there is a no of trade-offs like pagelook Vs lightweight, javasript Vs SEO etc.

We always like round corner in things whether it is furniture or car. But for web pages round corner is not so easy. There are a number of methods to include round corner in pages paragraphs images. But the easiest ways are not supported by all browsers.



In CSS3 there are some new special attributes included for the easy design of smooth corner boarder lines. But these code tags are different for different browsers . Actuallly it does not depend not on the browser but the layout engine which works behind it. Here is a list of layout engines.

Trident         Internet Explorer

Gecko            Firefox, Netscape

Web-kit        Google Chrome and Safari

Presto            Opera

These layout engines define their own notations, so there is a problem in creating cross browser designs.

#example1 {
border-radius: 15px;

However, for the moment, you’ll also need to use the -moz- prefix to support Firefox (see the browser support section of this article for further details):

#example1 {
-moz-border-radius: 15px;
border-radius: 15px;



The Syntax:

border-*-*-radius: <length> | <%> ] [ <length> | <%> ]?


border-top-left-radius: 10px 5px;
border-bottom-right-radius: 10% 5%;
border-top-right-radius: 10px;


The Syntax:

<length> | <percentage> ]{1,4} [ / [ <length> | <percentage> ]{1,4} ]?


border-radius: 5px 10px 5px 10px / 10px 5px 10px 5px;
border-radius: 5px;
border-radius: 5px 10px / 10px;


The following diagram gives a few examples of how corners might appear given differing radii:

If either value is zero, the corner will be square, not round.

For older versions of Mozilla

W3C Specification

Mozilla Implementation











But the Internet Explorer supports these properties only after IE9.

Cross Browser Examples

Here’s a few basic examples that should work in current versions of Firefox, Safari/Chrome, Opera and even IE9:


#Example_A {
height: 65px;
-moz-border-radius-bottomright: 50px;
border-bottom-right-radius: 50px;

#Example_B {
height: 65px;
-moz-border-radius-bottomright: 50px 25px;
border-bottom-right-radius: 50px 25px;

#Example_C {
height: 65px;
-moz-border-radius-bottomright: 25px 50px;
border-bottom-right-radius: 25px 50px;

#Example_D {
height: 5em;
width: 12em;
-moz-border-radius: 1em 4em 1em 4em;
border-radius: 1em 4em 1em 4em;

#Example_E {
height: 65px;
-moz-border-radius: 25px 10px / 10px 25px;
border-radius: 25px 10px / 10px 25px;

#Example_F {
height: 70px;
width: 70px;
-moz-border-radius: 35px;
border-radius: 35px;



Webbased code generator

Spoofy Corner

No images, Supports Mozilla and IE version before 9 also



Image based Corners

Another Image Generator

Generates a PNG format rounded corners for you on the fly. Simply copy the scripts below into a browser and hit enter. c=999999&bc=white&w=4&h=4&a=tr

Tweak the following parameters to get the rounded corners of your choice.



the color, as either a name or a CSS-style color spec (RGB or RRGGBB) sans #. Color names that seem to work: black white gray red green blue yellow teal olive purple. Can you find more?


the background color, same acceptable input as c


height in pixels


width in pixels


which corner to generate; tl is top left, tr is top right, bl is bottom left, br is bottom





A java library for round corner

Another code

Jquery based round corner



Embedded C

    Few days ago my guide asked a question what is difference between embedded C and standard C.

Difference between Embedded C and standard C

Standard C compilers output a binary file that can be run over a Operating system (windows/Linux). The compilers used for embedded C are cross platform compilers. The main difference is embedded C targets embedded system and standard C targets are Personal computer or servers. Embedded C gives more power to the user to access the memory at bit level. In embedded C the programmer has to write most of the codes himself there is no standard library. Because in embedded systems there is no common I/O is defined like our PC’s where the common I/O’s are the keyboard and the monitor.

  • Difference of the targets either embedded system or a normal PC
  • No standard library
  • No real-time system compatibility
  • Usually there is an infinite loop (not necessary in purely interrupt driven system) which is restricted in standard C
  • Programmers have to consider memory size, stack size as embedded systems have less memory
  • Bit level accessibility of memory
  • Extra data pointers