| Amplifier is widely used in analog signal processing, almost every analog system is built with an amplifier nowadays. Design of high precision amplifier has been being a challenge work for analog design. High precision amplifier has a very bright and wide application field, in which it is strict with noise performance and offset, such as sensing, medical, instruments signals amplifying and processing, high resolution analog/digital (digital/analog) converters.Work of this paper is made up of the circuits design of chopper amplifying and its layout realization.Because of human body bio-signals are very weak in amplitude, low in frequency and poor in anti-jamming, coupled with the poor noise and offset performance of usual amplifiers, usual amplifiers are not suitable for bio-medical amplification. So we give a brief analysis of three types of circuit techniques for realizing low noise and offset, bring up with a chopper-hold structure suitable for bio-medical processing. Chopper technique is used to give an odd number of modulation for noise and offset of amplifier, and an even number for useful signals. So, we realized the separation of noise and signal in this way. We can easily filter the useful bio-medical signals in base band under the help of a low pass filter, and at the same time, give a strong rejection for noise and offset.The circuit design of the chopper-hold amplifier is consist of three main blocks: clock generation block (OSC), three mode counter (Divider3) and the chopper-amplifying body.The CMOS techniques and usual problems are introduced in layout design work, some useful design rules and a specific blue print are also mentioned here. Calibre tools are used here for layout validate and post parameters extraction.The whole design are simulated and taped out with SMIC 0.18um 1P6M technique. |
PDF Full Text Request