Hangjing has issued an announcement on the upgrade and optimization of its domestically produced products.

In modern electronic devices, operational amplifiers are an indispensable component. Particularly in the design of domestically produced op‑amp circuits, selecting appropriate components and optimizing the circuit architecture have become focal points for many engineers. Today, we will delve into the key principles and techniques of designing domestic op‑amp circuits, helping you elevate your circuit‑design expertise. 1. Understand the Basic Characteristics of Operational Amplifiers First and foremost, when designing a domestic op‑amp circuit, it is essential to grasp the amplifier’s fundamental characteristics. The core performance of an op‑amp hinges on parameters such as gain, input impedance, and output impedance. Gain determines the signal‑amplification capability; input impedance affects the source‑load interaction; and output impedance influences the signal‑transmission efficiency. Only by thoroughly understanding these basic traits can we proceed with more effective circuit design. 2. Choose the Right Domestic Operational Amplifier While the market offers a wide array of domestically manufactured op‑amps, not every model is suitable for your specific project. When making your selection, consider several critical factors: bandwidth, power consumption, operating temperature range, and cost. For instance, if your application involves high‑frequency signal processing, bandwidth becomes the primary consideration. Conversely, for projects with stringent low‑power requirements, prioritize low‑power consumption.

With a commitment to customer responsibility and continuous improvement, Hangjing has long been developing and manufacturing new products in response to market and customer needs, while also pursuing the domestic substitution of imported integrated circuits. At the same time, it persistently upgrades and refines its established, mass‑produced standard products, enhancing their electrical parameters, broadening their applications, improving system performance, and maximizing customer satisfaction.

Recently, our company has completed the evaluation of imported operational amplifiers. OP07A With the instrumentation amplifier AD620 Products that have completed domestic substitution HJOP07 and HJG 620 Improvement and optimization efforts. Through a series of tests and evaluations, the technical team confirmed that the device’s electrical parameters have been comprehensively optimized compared to the original design, meeting the performance specifications of imported devices—and in some cases even surpassing them.

I. HJOP07 Product Improvement

HJOP07 It is a low-noise, chopper-stabilized, zero-drift bipolar operational amplifier. HJOP07 It features low input bias current, high open-loop gain, a wide input voltage range, high common-mode rejection ratio, and high input impedance. It is primarily used in high-gain measurement instruments and in applications involving the amplification and processing of weak sensor signals. It can deliver enhanced accuracy when configuring inverter circuits and is widely employed in miniaturized, high‑performance instrumentation for defense, military, oil‑exploration, and industrial applications.

Our team achieves the final packaged product by performing fine-tuning and optimization during the wafer fabrication stage. HJOP07 It can achieve a very low input offset voltage and requires no additional zeroing adjustments during operation.

1. Package Type

HJOP07 The encapsulation adopts D08S2 Ceramic dual in-line package, CSOP08B Surface mount 8 Wire micro-packaging, T-08 Metal circle 8 Wire packaging and F08-06 Ceramic flat‑pack package; see the appendix for the detailed package dimensions.

2. Lead-out Terminal Functionality

     

3. Comparison Before and After Optimization

Respectively for imports OP07A , before optimization HJOP07 and after optimization HJOP07 Electrical parameter testing and comparison are conducted on the devices, and simulation experiments are performed to evaluate the time‑drift characteristics of key electrical parameters.

 

 

Electrical Parameter Comparison Table

Unless otherwise specified, V _CC =+15V ， V _EE =-15V ， RL=2kΩ ， T _A =+25℃ 。

By comparing the electrical parameters of the three devices, it is readily apparent that, after optimization, HJOP07 Its input offset voltage is lower, it exhibits superior common-mode rejection ratio and power-supply rejection ratio, has a higher open-loop voltage gain, and consumes less static power. In other words, the optimized design… HJOP07 The electrical parameters are superior.

For the optimized device HJOP07 Electrical parameter items and their time drift characteristics (electrical parameter items with significant characteristics) were subjected to simulated experimental testing. Under constant temperature conditions, the optimized… HJOP07 The device underwent a one-month temperature‑drift stability test, and the results showed that the optimized device exhibits a temperature‑drift error of approximately… 0.8 μV/mon , fully capable of matching imported components OP07A Parameter requirements.

Based on the above experiments and comparative analysis, after optimization HJOP07 The electrical parameters consistently meet the requirements of previous devices and even outperform both earlier models and imported counterparts, enabling the replacement and upgrade of legacy products.

II. HJ G 620 Improvement of

HJ G 620 It is a low-power, high-precision instrumentation amplifier whose gain can be adjusted via an external resistor, ranging from… 1 ~ 10000 It is adjustable. Featuring high precision, low nonlinear error, low offset voltage, small bias current, low noise, short settling time, and minimal temperature drift, this device is ideally suited for high‑precision data acquisition systems—such as weighing instruments, sensor interfaces, multiplexing applications, and battery‑powered, portable, or mobile devices—thanks to its compact size and low power consumption.

1. Package Type

HJG620 The encapsulation adopts D08S2 Ceramic dual in-line package and F08-06 Ceramic flat‑pack package; see the appendix for the detailed package dimensions.

2. Lead-out Terminal Functionality

                 

3. Comparison Before and After Optimization

Respectively for imports AD620 , before optimization HJG620 and after optimization HJG620 Electrical parameter testing and comparison were conducted, with the test results shown in the following table:

Electrical Parameter Comparison Table

Unless otherwise specified, V _CC =+15V ， V _EE =-15V ， R _L =2kΩ ， T _A =+25℃ 。

 

By comparing the electrical parameters of the three devices, it is readily apparent that the optimized one… HJG620 The electrical performance parameters are generally superior to those of the previous product, and the issues observed in the earlier version—namely, significant gain error at high gain settings and poor common-mode voltage rejection at low gain—have been addressed. Comparative testing of the electrical parameters reveals that, following optimization, HJG620 It offers superior performance and can be used to upgrade and replace legacy products.

Imported components AD620 During the design, a series connection was implemented in both input-stage circuits. 400Ω of resistance; these two resistors enable the device to reliably and safely withstand up to +15V Voltage or current 60mA Overload for several hours; provided the current does not exceed 6mA ( I _IN ≤V _IN /400Ω ), the resistance to input overload will be longer. Due to the series input resistor in the design, the instrumentation amplifier exhibits sufficient robustness during power-up, power-down, or when the input stage is subjected to abnormal electrical surges. Without this 400Ω In such cases, if the input stage experiences a transient overvoltage exceeding the supply voltage, the device’s functionality may be easily compromised.

In view of imports AD620 the design concept, this time regarding HJG620 During optimization and improvement, the input stage of the instrumentation amplifier was also addressed by connecting an approximately … in series at the device’s input stage. 400Ω The resistance is increased to enhance the device’s ability to withstand abnormal surge signals, thereby improving the reliability of the optimized device.

Based on the above experiments and comparative analysis, after optimization HJ G620 The electrical parameters consistently meet the requirements of previous devices, while offering superior performance compared to both earlier models and imported counterparts, thereby enhancing device reliability and enabling the replacement of legacy products.

 

In the coming years, China will enter a critical period of strategic opportunity and a phase of intensive effort in developing its integrated circuit industry. While continuing to research and develop proprietary new products, the company will steadily advance the domestic substitution of existing components. Furthermore, it will focus on delivering end-to-end solutions, leveraging customer‑specific requirements to design, refine, and optimize application‑specific integrated circuits and functional modules that can significantly enhance system performance, thereby maximizing customer satisfaction.

 

Hangjing Microelectronics will, together with all stakeholders, embrace the philosophy of “pursuing development through innovation and ensuring survival through quality,” to meet challenges and seize opportunities, thereby achieving a high level of scientific and technological self-reliance and strength.

III. Appendix