Research On Low Power Output Variable CMOS Power Amplifier Design

With the continuous development of semiconductor technology,RF power amplifiers can be integrated into millimeter-wave radar sensor systems.The radar sensor system is mainly composed of antenna,millimeter wave transceiver front-end,digital signal processing and radar control circuit.For millimeter-wave radar,the antenna and the millimeter-wave transceiver front-end work in the millimeter-wave band and are the core components of the millimeter-wave radar.As the core module of the entire transceiver front-end,the RF power amplifier is often a major difficulty in design.The RF power amplifier undertakes the task of amplifying the microwave signal generated by the phase-locked loop inside the radar chip and transmitting it to the antenna.It is the most energy-consuming module in the entire transceiver chip and the module with the strongest nonlinearity.In millimeter-wave radar chips,high-performance and compact power amplifier circuits are the products that are urgently needed by the market.Generally speaking,the performance of an RF power amplifier is largely determined by the manufacturing process,and each process has different characteristics or advantages for the power amplifier.For the consumer electronics category,the cost of the product is a decisive factor in power amplifier design and mass production.In recent years,with the improvement of the CMOS technology level,the feature size has been continuously reduced and the cut-off frequency has been continuously increased,which fully meets the requirements of RF integrated circuit design,and is easy to integrate with digital and analog systems with high integration density and low power consumption,so that the system has the advantages of low cost,high integration and wide application range.This paper designs a RF power amplifier module based on SMIC 0.13 ?m CMOS standard process,the amplifier works in C-band(5725MHz-5875MHz),adopts the class AB working mode,and is integrated in the transceiver front-end system of FM continuous wave radar.Since the envelope of the transmitted signal of the FM continuous wave radar is constant,the linearity of the power amplifier is not required too high,and the power amplifier does not need to work in the power back-off area.The whole power amplifier module mainly includes driver stage circuit,bias circuit,power amplifier core circuit and on-chip balun.The self-biased driver stage circuit is used to reduce the chip area and power consumption.The output stage circuit adopts a cascode differential structure to improve the voltage withstand capability of the transistor and higher reverse isolation than the cascode stage.The on-chip balun converts the differential RF signal into a single-ended output signal and transmits it to the antenna receiving end.At the same time,the balun also undertakes power synthesis and certain output impedance transformation.The pre-simulation,layout design and post-simulation of the RF power amplifier were carried out in the Cadence software environment,and finally the chip was tape-out in SMIC.The chip area of the power amplifier module is 0.4*0.26mm2.The simulation results show that: the driver stage circuit works under the power supply voltage of 1.2V,the output stage circuit works under the power supply voltage of 2.5V,the RF output signal frequency range is 5725MHz-5875 MHz,the gain is 10 d B,and the output power is adjustable in the range of-10 d Bm-5d Bm,the current consumption is 11 m A under the maximum transmit power,and the harmonic suppression of the transmit signal is greater than 47 d Bc.The test results after tape-out meet the index requirements.