Neural-recording systems amplifier

These applications, by nature, impose serious limitations on power and area in the design of neural-recording systems. Researchers have developed several kinds of neural-recording systems [23-27], and those systems are generally composed of preamplifiers to amplify the small extracellular potentials, low-pass filters to reject the high frequency noise, multiplexers, and analog-to-digital converters (ADCs) followed by the wireless telemetry circuits to transmit data out of the body. 

Figure 13 shows the schematic of the preamplifier, which is composed of an operational transconductance amplifier (OTA) and a feedback network. A capacitive negative-feedback amplifier is widely used in neural-recording systems [28] because there is usually a DC offset of 1—2 V across the electrode-tissue interface [29]. The gain of the amplifier is determined by the ratio of the two capacitances in the feedback network. 

Unlike other UWB applications, power amplifiers are not necessary due to the low transmitted power and short distance range in neural-recording systems. Instead, a wideband-matching filter is used to regulate the transmitted power. 

Wattanapanitch, W., M. Fee, and R. Saipeshkar. 2007. An eneigy-efficient micropower neural recording amplifier. IEEE Transaction on Biomedical Circuits and Systems 1(2) 136-147. 

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