17-10-2017, 10:36 AM
An analog chip is a set of miniature electronic analog circuits formed in a single piece of semiconductor material. The voltage and current at the points specified in the circuits of the analog chips vary continuously over time. In contrast, digital chips only use and create voltages or currents at discrete levels, with no intermediate values. In addition to transistors, analog chips often have a greater amount of passive elements (inductors / capacitors / resistors) than typical chips. Inductors tend to be avoided because of their large size, and a transistor and capacitor together can do the work of an inductor. (When this method is used in a CFL, an electronic ballast is obtained).
Analog chips may also contain digital logic elements to replace some analog functions, or to allow the chip to communicate with a microprocessor. For this reason and since logic is commonly implemented using CMOS technology, these chips use BiCMOS processes by companies such as Freescale, Texas Instruments, STMicroelectronics and others. This is known as mixed signal processing and allows a designer to incorporate more functions into the chip. Some of the benefits include load protection, reduced parts count and increased reliability.
Pure analog chips in information processing have been replaced mostly by digital chips. Analog chips are still required for broadband signals because of sampling rate requirements, high power applications and transducer interfaces. Research and industry in the field continues to grow and thrive. Examples of known and long-lived analog chips are the operational amplifier 741 and the 555 timer.
Power supply chips are also considered as analog chips. Its primary purpose is to produce a well-regulated output voltage supply for other chips in the system. Since all electronic systems require electrical power, integrated power supply circuits (PMICs) are important elements of such systems.
The important basic building blocks of the analog chip design include:
1. current sources
2. current mirrors
3. differential amplifier
4. Band change references.
All previous circuit building blocks can be implemented using Bipolar technology, as well as Metal-Oxide-Silicon (MOS) technology. The references of the MOS Band gap use lateral (poor) bipolar transistors for their operation. People who have specialized in this field include Bob Widlar, Bob Pease, Hans R. Camenzind, George Erdi and Barrie Gilbert, among others.