Study On Low-power High-speed Implantable UWB Transmitter And Receiver

With the rapid development and combination of information technology, semiconductorintegration technology, biomedical electronics technology, the implantable microelectronictechnology has become an emerging research field. Without destroying the integrity andactivity of the biological nervous system, wireless implantable microelectronic devices cantransmit and monitor the bio-electricity signal in real time, promoting the research of livingorganism tissue. In this field, compared to traditional narrowband wireless communicationtechnology, UWB wireless communication technology has the advantages of large channelcapacity and good coexistence which is benefit for transmitting the multi-channel andhigh-precision bio-electricity signals. The implantable environment provides extremelylimited energy and space to in-vivo devices. Therefore, power, complexity, volume andefficiency become the focuses and key challenges of UWB wireless communicationtechnology applied in this field.In this thesis, a low-power, low-complexity, high-speed UWB wireless communicationsystem and systematic design solution have been studied. Baesd on0.18m CMOStechnology, several chips have been implemented, such as a low-power UWB transmitteroperating in burst mode, a low-complexity UWB transmitter based on filtering and shaping, alow-complexity UWB squarer-filter receiver. The above study was supported by the NaturalScience Foundation of China (60976026).The proposed low-power UWB transmitter operating in burst mode integrates OOKnarrow pulse generator, differential triangular narrow pulse generator, ON-OFF VCRO, RFbuffer, etc. The chip can generate3-5GHz UWB RF signal with a sidelobe rejection of morethan30dB with a low energy consumption of20pJ/bit at250Mbps and a small core chipsize of0.08mm~2.The proposed low-complexity UWB transmitter based on filtering and shaping techniqueintegrates OOK narrow pulse generator, filtering and shaping circuits, a novel UWB PA withtunable radiation power, etc. The chip can generate3-5GHz UWB RF signal with a sideloberejection of more than20dB with a low energy consumption of8pJ/bit at250Mbps, atunable radiation peak power of-30~-50dBm, and a core chip size of0.32mm~2. The proposed low-complexity UWB squarer-filter receiver chip integrates UWB LNA,UWB active balun, squarer, low-pass filter, wide band VGA, high-speed comparator andbase-band interface, bandgap reference, etc. The chip can receive3-5GHz UWB RF signalwith the highest data rate of250Mbps, a receiving sensitivity of-79dBm, a bit error ratelower than10-4, an input matching lower than-10dB, a power consumption lower than26mW and a chip size of2mm~2.The achievements of this thesis are as follows:First, combining innovative complementary switch with self-biased technique andtriangular narrow pulse generator with push-pull charge pump technique are proposed. Thenovel ON-OFF VCRO driven by triangular narrow pulses is realized to generate the UWB RFsignal. The output PSD of the proposed low-power UWB transmitter operating in burst modeshows excellent spectral efficiency in compliance with FCC mask, without a large area of LCfilter and shaper. Due to operation in burst mode, this chip achieves low power consumption,high speed and excellent radiation efficiency.Second, a new type of gate input and current mode output UWB power amplifier (PA) isproposed based on RC parallel feedback technique. The novel PA makes the proposedlow-complexity UWB transmitter based on filtering and shaping technique satisfy ultra-widefrequency band impedance matching, provide a range of20dB tunable radiation power andmeets the requirement of different implantable environment.Third, by introducing an asymmetric inductor in series with the NMOS gate combiningwith RCL parallel negative feedback technique, a novel push-pull UWB LNA with high gainflatness is proposed. It makes the proposed UWB receiver get good signal-to-noise ratio andinput impedance matching of ultra-wide frequency band.Fourth, the phase correction circuit in the UWB active balun is designed to obtain anextreme low differential phase deviation for the proposed UWB receiver. It garantees thedifferential matching and gain stability of the UWB receiver.Fifth, a new high linearity squarer with a pair of linear region MOS transistors isproposed to implement multiplication or square. Due to no multiple-order nonlinear term inthe output of this squarer, it also can be used as a mixer of ultra high frequency.Sixth, the zero-pole compensation of inductor and capacitor are adopted to implement a novel wideband VGA. The circuit with active inductor load achieves a small physical area,expands the bandwidth of the VGA and ensures an adjustable dynamic range of UWBreceiver from0to40dB.In summary, the results of this thesis not only can be used as a reference for the researchof biomedical implantable high-speed wireless communication, but also can be used forindoor wireless interconnect applications which has a harsh demand for power consumptionand transmission speed.