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

摘要

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 mu m(2) and 737.87 mu m(2) 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 MHz, while the received frequency is set at 66.6 MHz. Therefore, the high amount of 60% is obtained for the data rate to carrier frequency ratio. Designed in a standard 0.18-mu m CMOS process, the proposed circuits operate at 1.8 V supply voltages with consuming almost 400 pj energy for transmitting each data bit.