Research And Design On Super-regenerative Receiver Based On Crystal Oscillator For Wake-up Application

Rencently the emerging technologies of wireless communication have propelled the rapid progress of wireless internet of things(Io T),and the low power technology of wireless sensor network(WSN)is one of hot research field.This dissertation investigates the active wake-up receiver for low power wireless WSN nodes,and pays attention to how to exploit the necessary crystal oscillator(XO)in almost every wireless nodes,then proposes a new wake-up scheme using super-regenerative receiver(SRR)based on XO.This dissertation will study the key technology difficulties in this scheme,such as the ultra slow start-up and quenching of an XO,the poor frequency selectivity of SRR,etc.Since the XO in the node has been extended not only a role of reference clock source but also a wake-up receiver(Wu R),there is no need for a dedicated Wu R with large size of LC tank circuits any more,so the board area and the power are saved dramaticly.The main work and achievements include following:1.This dissertation analyzes the similarity and characteristic of WSNnodes,and proposes a new wake-up scheme with shared XO and SRR.Thetheoretical research proves the feasibility then the performance canbe analyzed further.2.This dissertation studies the limit of the start-up speed inconventional XO,and proposes an ideal architecture of XO withintrinsically fast start-up characteristic,then designs the fast XOwithout any injection as used in other's work.The simulation andmeasurement results of such XO with balanced differential feedbackloop can show more than 10 times faster than conventional XO,whichhas achieved the state of art in fast XO currently.3.Using the idea of inversely driving by the amplifer of XO,thedifficulty to quench quickly an oscillating cystal with full energyis overcome.4.To realize the repeatedly start-up and quenching,a relaxionoscillator is designed to control the running of SRR,which provideslinear ramp type damp factor and improves the frequency selectivity.5.To ensure enough practicability of the critical condition of balancedloops for fast start-up,this dissertation proposes a mechanism andalgorithm based on the repeat start-up of SRR,in which the parasicitoscillating is utilized as the criterion of exact balance,then theappropriate capacitance is reached after several steps of binarysearching.Hence the robustness of balanced condition can beguaranteed over PVT variations with enough accuracy.6.The proposed SRR is implemented in a 0.18 ?m CMOS process to verifythe design.The measurement is carried with a 26 MHz crystal and 5p Fload capactance.The sensitivity of-78 d Bm,and 1.1 k Hz 3-d B bandwidthand 1.8 k Hz 10-d B bandwidth are achieved.Total receiver exhibitssimplicity without any frequency calibration,and the frequencyselectivity is improved at least 50 times than currently reportedworks.7.As an application example,this SRR based on XO is applied as a Wu Rin a car PKE system.The test results show good performance to reducethe area and weight,along with the power consumsing.