Microwave Millimeter Wave Vector Modulator And Application

Microwave and millimeter wave vector modulator has the ability to control the amplitude and phase simultaneously with the advantage of high modulation accuracy,low cost,miniaturization and so on.It has been widely used in RF reflection power cancellation system of frequency modulated continuous wave(FMCW)radar,feedforward linearization technology of power amplifier,amplitude and phase correction of multi-channel transceiver system,beam control of phased array antenna,high-performance reader of RFID system and other technical fields.For the sake of realizing UHF-band vector mudulators with high linearity and E-band vector modulator with high precision and low cost,the amplitude and phase modulation characteristics of the UHF-band vector modulator based on the PIN diode biphase modulator circuit and the millimeter wave vector modulator based on the E-band I/Q modulator MMIC chip are analyzed in depth.The scheme of reflection power cancellation(RPC)system is analyzed and designed,and the key circuit modules in the system are developed.The main achievements of this thesis are as follows:1.In the case of high cancellation ratio in UHF-band RPC system,the linearity of vector modulator becomes an important factor affecting the phase noise of receiving system.Utilizing feature of the high power capacity PIN diode,a single balanced vector modulator at UHF-band with medium and high power capacity is developed by using unbalanced dual-phase modulator structure.Based on the ADS software,amplitude and phase modulation characteristics and the linearity of the output power are simulated and analyzed by using the single balanced vector model.A prototype of the vector modulator is fabricated and the circuit parameters and performance are tested.The measurement results demonstrate that the vector modulator has an amplitude modulation range of 34 dB,a phase modulation range of 360 degrees,and good input-output power linearity characteristics at 950 MHz frequency.2.To improve the symmetry of the constellation diagram of the single balanced vector modulator and further improve the linearity of the output power of the vector modulator,the dual balanced vector modulator in UHF-band is developed by using the same PIN diode with the circuit structure of the balanced dual-phase modulator.Firstly,according to the requirement that the dual-balanced circuit structure needs complementary voltage for control,the control voltage value under a certain series resistance condition when the impedance of the PIN tube presents to 50 ohms is determined based on ADS simulation software,and a conversion circuit of two-to-four way control voltage is designed accordingly.The results of the sample circuit demonstrate the amplitude modulation range of the vector modulator at 950 MHz reaches 38 dB,the phase modulation covers 360 degrees,and the phase orthogonality error of I/Q is less than 2 degrees.The orthogonality of I/Q and the linear workspace with amplitude modulation are obviously improved compared with the single balanced structure.3.In view of the current growing demand for E-band FMCW radar RF cancellation system and other applications,but there is no commercial vector modulator chip available for RPC product research and development in this band,this thesis studies the feasibility of using commercial I/Q modulator MMIC chip to realize high-precision E-band vector modulator.The characteristics of E-band vector modulator are experimentally studied by using gMDR0013 B modulation/demodulation chip.The dual-phase modulation characteristics of I and Q circuits are realized by using the polarity of the I and Q DC modulated signals in differential form.The amplitude modulation of I and Q signals is realized by the amplitude modulation of the modulated signal.The S21 parameters of the modulator under different modulation voltages are measured by a 3mm-band vector network analyzer to investigate the modulation characteristics of its amplitude and phase.The measured results at the 77 GHz frequency point show that the I/Q modulator has an amplitude modulation range of 26 dB and a phase modulation range of 360 degrees.The above experimental results prove the feasibility of using the I/Q modulator chip to realize the vector modulation function.4.An E-band RPC system scheme with the above I/Q modulator as vector modu lator is proposed,and the system parameters are analyzed and designed.Firstly,an mathematical model of analog closed-loop RPC system is established,the factors affecting cancellation performance are analyzed and the detailed design scheme of the whole RPC system is determined.The key circuit modules that make up the RPC system are developed and their debugging and testing work of each module is completed,which lays an important foundation for subsequent system integration.