Let's make a simple historical review of the amplifiers (such as LM709) that require external compensation and external disordered adjustment components. Most of these products are made by bipolar technology on two-inch wafers. They provide only double-column direct-insert (DIP) packaging and TO-99 metal round shell package, and its main application area is industrial instrument/meter. Its low power consumption means that a few milliampere (mA) current is absorbed from the power supply of ±15 V. The technical indicators given by the manufacturer only emphasize its Direct Current (DC) parameters; These products have a low qualified rate, but the price is very high.
In today's precision operational amplifier
field, weak signal design engineers focus on some important factors, such as low power supply current, low disturbance voltage, low noise, low bias current etc. The latest amplifier uses innovative design and technology to provide performance that constantly exceeds users' expectations. Design engineers adopted the circuit and the product testing technology (such as self-stabilizing zero, digitrim digital fine-tuning, blown fuse and laser trimming resistor) to promote the optimization of each technological index, thus designed amplifier of that several specific parameters are close to the ideal index. The offset voltage index for the amplifier (such as AD8628) has been optimized to a few microvolts (μV).
Manufacturers have made significant progress in all aspects of process technology. These advances allow the amplifier design engineers to give full play to the performance and function of each process. CMOS technology has benefited from advanced technology (driven by digital microprocessors), and analog amplifier design engineers have used it to gain high performance at low cost. In the past, ultra-high performance amplifier products need to be designed with bipolar technology. Now, the analog amplifier design engineers can overcome the disadvantages of the high noise from CMOS process voltage, and they have both low noise and ultra-low bias current (possibly from the oxide-insulated gate).