Chaotic inductively coupled non-PLL low emission transmitter for implanted devices

The current work proposes a low emission frequency shift keying (FSK) non-PLL based modulator for transmitting neural signals. FSK has been shown to be viable alternative to widely used ASK (Amplitude Shift Keying). Designers need to start developing low Electromagnetic Interference (EMI) algorithms for implanted devices so as to minimize interference. The proposed algorithm utilizes a ramp to modulate the bit stream from the neural amplifier. The encoded signal is further non-linearly modulated ensuring a lower peak in the power spectrum, a measure of electromagnetic interference. The propose circuit has been fabricated in 0.18μm AMS technology.