A High-Data-Rate Area-Efficient Uni-Pulse Harmonic Modulation Transmitter for Implantable Neural Recording Microsystems

Abstract

In this paper, a new data transmission method, named Uni-Pulse Harmonic Modulation (PHM), is presented and its concept is mathematically analyzed using the relations of inductive links. In this type of modulation, the Uni-Pulse passing through the primary coil generates an oscillation in the secondary coil, corresponding to its positive edge, and its negative edge is able to damp this oscillation. The Uni-Pulse passing the primary coil gives the opportunity to use a half-bridge driver instead of full-bridge driver and hence the chip area is desirably reduced. For implementing the proposed modulation technique, two half-bridge driver circuits are suggested that are controlled by series of transistors and transmission gates occupying 900[Formula: see text][Formula: see text]m2 and 737.87[Formula: see text][Formula: see text]m2 of chip area, respectively. Another merit of the proposed transmitters, besides their occupying low chip area, is that they can transmit data at the rate of 40[Formula: see text]MHz, while the received frequency is set at 66.6[Formula: see text]MHz. Therefore, the high amount of 60% is obtained for the data rate to carrier frequency ratio. Designed in a standard 0.18-[Formula: see text]m CMOS process, the proposed circuits operate at 1.8[Formula: see text]V supply voltages with consuming almost 400[Formula: see text]pj energy for transmitting each data bit.