Research And Design Of Transmitter Based On Ultra-Wide Bandwidth

At present,Ultra-Wideband(UWB)technology is an important development direction of the field of communication,UWB technology and other communication technology,compared with the capture / detection of the probability is very low,anti-interference ability,anti-multipath Interference ability,penetrating ability and so on.In addition,the maximum data transfer of ultra-wideband systems can reach tens of megabytes per second to several gigabits per second.Moreover,ultra-wideband devices have a simpler transceiver circuit than narrowband transceivers,and therefore have a small,low-cost feature in production.Ultra-wideband communication has become one of the hot issues in recent years.In this paper,the transmitter front structure with the Gaussian pulse generator and the oscillator is designed and analyzed.The pulse generator generates narrow pulses under the control of the baseband data,and the Gaussian pulse is the most basic theoretical model of the radio.Gaussian pulses can provide good time-frequency characteristics.In this paper,an RC differential circuit is designed by the avalanche effect of the crystal transistor.The square wave signal can be transformed into a signal with positive and negative pulses through the differential circuit.When the forward pulse signal enters,the three-level tube is triggered by the pulse and enters the avalanche area.At this time,the three-level avalanche performance is formed to form a very narrow pulse signal,and the third-order Gaussian pulse is obtained through the output port.The output of the pulse generator is on the rising edge of the input square wave,which conforms to the OOK modulation of the signal.The output pulse width is about 1ns,and the width of the output pulse is not affected by the input signal,which meets the requirements of UWB communication.The center frequency of the pulse generated by the overall transmitter is determined by the oscillation frequency of the oscillator.The design of the oscillator takes into account the ring oscillator,LC cross-coupling oscillator two.The ring-shaped voltage-controlled oscillator is easier to integrate on-chip,but if the same phase noise,the ring oscillator power consumption will be relatively large;at the same time as the device size is reduced,the power supply voltage will be reduced,then Phase noise will increase.However,LC voltage-controlled oscillator phase noise performance is better,but the LC voltage-controlled oscillator also requires passive inductance,the inductor quality factor requirements are relatively high.The design of the ring-shaped voltage-controlled oscillator uses the topology of the differential-multiplexed ring oscillator.The delay unit selects the double delay path and uses the TSMC 0.18?m RF CMOS process model library to complete the simulation.When the control voltage in the 0 ~ 3V change,the circuit can work in 3.4GHz ~ 5.4GHz,tuning range width of 2GHz.LC cross-coupling oscillator selected in the complementary cross-coupling oscillation structure,variable capacitor for the inverted MOS tube to increase the voltage tuning range.When the tuning voltage in the 0 ~ 4V changes,the circuit can work in 3.2GHz ~ 5.2GHz,tuning range width of 2GHz.When the frequency is 4.2 GHz,the phase noise at 100 k Hz is-94.335 d Bc / Hz and the phase noise at 1 MHz is about-114.237 d Bc / Hz.The transmitter designed in this paper contains a Gaussian pulse generator and an oscillator.Under the control of the baseband data,the pulse generator generates a 3rd order Gaussian pulse signal that is only output at the rising edge of the baseband signal.The center frequency of the pulse generated by the overall transmitter is determined by the oscillation frequency of the oscillator.Combine two different structure of the oscillator,through the simulation of the transmitter output pulse.It is possible to realize "OOK" modulation in which the transmitter operates only on the rising edge of the input square wave.Two different structures are the front part of the transmitter oscillator,using a voltage controlled ring oscillator structure,input square wave frequency can be adjusted in the range of 10MHz~300MHz,the power supply voltage 1.8V,power consumption of the circuit is 34 m W,the output pulse width is about 2ns,pulse peak 16 m V.For the LC cross coupling structure,the input square wave frequency can not exceed 50 MHz,the supply voltage is 1.8V,the circuit power consumption is 58 m W,the output pulse width is about 10 ns,and the pulse peak value is 8mV.