A Low Power ASK Clock and Data Recovery Circuit for Wireless Implantable Electronics

This paper describes a low power clock and data recovery (CDR) circuit with integrated ASK demodulator for wireless implantable neural recording microsystems. A modulation scheme based on amplitude shift-keying (ASK) and pulse position modulation (PPM) is employed to simplify the complexity of implant circuits and reduce power transmission requirements. A charge-pump based CDR circuit is used to extract non-return to zero data from the demodulated waveforms. A prototype has been fabricated in 2-poly 3-metal 0.6mum bulk CMOS technology in order to validate circuit functionality. The receiver front-end exhibits a sensitivity of 3.2mV p-p at 1MHz. The ASK demodulator and CDR operates over an input data range of 4kbs to 18kbs, measures 300pm by 600pm and dissipates 70pW from a 2.7V supply

[1]  W. Liu,et al.  A neuro-stimulus chip with telemetry unit for retinal prosthetic device , 2000, IEEE Journal of Solid-State Circuits.

[2]  K. Kimura.  A CMOS logarithmic IF amplifier with unbalanced source-coupled pairs , 1993 .

[3]  K. Najafi,et al.  Low-power interface circuits for bio-implantable microsystems , 2003, 2003 IEEE International Solid-State Circuits Conference, 2003. Digest of Technical Papers. ISSCC..

[4]  Wentai Liu,et al.  A smart bi-directional telemetry unit for retinal prosthetic device , 2003, Proceedings of the 2003 International Symposium on Circuits and Systems, 2003. ISCAS '03..

[5]  Daryl R. Kipke,et al.  Wireless implantable microsystems: high-density electronic interfaces to the nervous system , 2004, Proceedings of the IEEE.

[6]  W. Ko,et al.  Design of radio-frequency powered coils for implant instruments , 1977, Medical and Biological Engineering and Computing.