Neural recording amplifier

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. 

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. 

Olsson RH, Gulari MN, Wise KD (2002) Silicon neural recording arrays with on-chip electronics for in-vivo data acquisition. IEEE EMBS Int Conf 237-240 Harrison RR, Charles C (2003) A low-power low-noise CMOS amplifier for neural recording applications. IEEE J Solid-State Circuits 38 958-965... 

The amplified neural activity was monitored with a storage oscilloscope and an audio analyzer, and stored on magnetic tape. Multiunit activity was summed using a short-time averaging circuit with a time constant of 0.5-1.0 sec (Kiyohara and Tucker, 1978), and displayed on a pen recorder. 

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