High Precision Small Current Amplifier with Automatic Gain Control in Integrated Semiconductor Parameter Analyzer
Wengang Wang · UTUPub (University of Turku) · 2019
Semiconductor is widely used in integrated circuits, power and lighting devices; precise measuring of electric facilities of electronic devices such as diode, triode, MOS transistor and optoelectronic devices is very important in semiconductor research and circuits or systems design, the measuring approach includes DC, pulse and C-V measurement. The instrument used to analyze electric facilities of semiconductor devices is called semiconductor parameter analyzer, it is the key of analyzing semiconductor devices, which have high market value. Currently most of the semiconductor parameter analyzer is imported from the United States, such as Keithley 4200 series of Tektronix® and B1500 series of Keysight®. Keithley 4200A-SCS parameter analyzer delivers synchronizing current-voltage (I-V), capacitance-voltage (C-V) and ultra-fast pulsed I-V measurements; Keysight® B1500A parameter analyzer delivers current-voltage (IV) measurement of spot, sweep, sampling and pulse, Quasi-Static Capacitance-Voltage (QS-CV) measurement, advanced pulsed IV and ultra-fast IV measurement. Small current amplifier is the key unit of semiconductor parameter analyzer, which is also the keystone and difficulty of its development. Small current amplifying is to transform small current signal into voltage and frequency signal, make it easier for the instrument’s monitoring and display. Small current signal is dedicated, so there are some obstacles when we design the small current amplifier. This design is the key procedure of the analyzer’s development. In this design we’d like to amplify the small current by I/V transform, it can respond quickly with wide and adjustable range of measurement. Its input bias current and impedance can satisfy our requirement when seriously select the amplifier and strictly follow the technology process. The testing result indicates that the smallest detected current of the amplifier reaches pA order of magnitude, which is a competent value compared with the current analyzer, while its cost is much lower (hundredths of it) and it is portable.