2.45 GHz, 100 Mbps BPSK-DSSS transmitter for interference-robust wireless neuroprosthetic networks

We present a 2.45 GHz 100 Mbps transmitter for body-implantable wireless neuroprosthetic links. Binary phase-shift keyed (BPSK) modulation with direct sequence spread-spectrum (DSSS) signaling and a 32-bit wide pseudo noise (PN) code is used to create energy-efficient interference-robust communication link. Power consumption is minimized by using a novel transmission-gate based low-loss passive mixer and energy-efficient system integration. The phase-locked loop consumes only 700 μW with -118.7 dBc/Hz phase noise at 10 MHz offset and -51.5 dBc reference spur. The transmitter consumes 17 pJ/b at a data-rate of 100 Mbps with -11 dBm of output power.

I. Introduction

It has been demonstrated that partial motor function can be restored in patients with spinal-cord injury (SCI) by implanting neuroprosthetic devices (NPDs) to stimulate the pheripheral nervous system (PNS) [1]–[2]. Due to unpredictable environmental conditions and highly non-linear muscle responses, high-speed real-time feedback from NPD to the control node using an on-chip transmittor (Tx) is extremely important [1]–[3], as shown in Fig. 1. Based on the neuromuscular feedback, the control node can generate stimuli for the desired motor function with greater accuracy [3]–[4].