斩波稳零运算放大器原理介绍.pdf

Chopper Amplifiers Achieving Precision Chopper Amplifiers Paul Rako Strategic Application Engineer Amplifiers Group 2 © 2004 National Semiconductor Corporation Chopper Amplifiers ïA chopper amplifier is a type of amplifier that exhibits precise outputs and low noise. ïAlso called Auto-Zero, Auto-Null, Ping-Pong, Stabilized and Commutated Amplifier. ïA chopper amplifier is often a compound amplifier. © 2004 National Semiconductor Corporation What is a Chopper good For? ïWhat is a precision amplifier? ïWhy does offset matter? ï Terms: Bias, common mode, gain, modulation, servo, AC coupling, © 2004 National Semiconductor Corporation What’s the big deal with offset voltage? ïWhat is a precision amplifier? ïWhy does offset matter? ï Terms: Bias, common mode, gain,chopper amplifier, servo, inverting © 2004 National Semiconductor Corporation Precision Defined: ïA precision amplifier is an amplifier that outputs and accurate representation of the input signal. This output will be accurate from part to part, over time and over temperature, barometric pressure, sunspots and any other external factors. © 2004 National Semiconductor Corporation Precision Defined: © 2004 National Semiconductor Corporation Offset Voltage ï Offset voltage is the voltage difference on the minus input pin of an amplifier that causes the output to be the same as the plus input pin (with Vcm=0). -