The Research And Design Of The Current Mode Up-conversion Mixer And Power Amplifier

With the rapid development of wireless communication technology, the personalcommunication systems such as interphone, cordless phone, digital cell phone etc, anddigital broadcast television, wireless internet access, global positioning system areused widely. Correspondingly, the demand for low cost, low power, low voltagewireless communication systems is also growing. The development trend isintegrating the radio frequency(RF) circuits with the digital baseband circuits on onechip to realize system on chip(SOC). But the operating voltage and power dissipationof the RF circuits and digital baseband circuits is inconsistent, it is a major bottleneckfor realizing the monolithic of the wireless communication system.Recently, a kind of circuits which take current as signal variables, called ascurrent mode circuits, have come up. Compared with the traditional voltage modecircuits, current mode circuits have the unique advantages such as low voltage, lowpower dissipation, wide frequency band, large dynamic range and so on. It can solvethe bottleneck mentioned above and it is adopted more and more in the design of theradio frequency integrated circuit.RF transmitter is between the digital baseband circuits and the antenna. Itsperformance would directly affect the whole wireless communication system. Thispaper adopts the current mode design method to design the key modules in the RFtransmitter. It lays a solid basis for realizing low-voltage, low power current mode RFtransmitters. The main work and innovation are as follows:(1)A2.4GHz highly linear current mode up-conversion mixer is proposed. Themixer replaces the trans-conductance of the traditional Gilbert mixer with theimproved current mirrors, leaves out the rail-transistor and adopts the currentbleeding method. The simulation results indicate that the mixer has good isolation andit achieves12.03dBm third-order input intercept point (IIP3),5dB conversion gainand16.8dB noise figure while its power dissipation is only3.8mW under1.2V supplyvoltage.(2)A2.4GHz high efficiency current mode power amplifier is presented. Thepower amplifier(PA) consists of two-stage differential amplifiers. The first stage is adriving amplifier which can accept and amplify the current waveform input signal, itbelongs to current mode class-A amplifier; the second stage is a current mode class-D amplifier and used as power output part, it has high efficiency and output power. Thesimulation results indicate that the PA has the peak Power Added Efficiency (PAE) of33.5%, saturated output power of23.6dBm, the power gain of23.6dB, S11and S22are both less than-10dB under the supply voltage of3V.The design of the two modules above adopts Chartered0.18μm RF CMOSprocess. Using the Cadence software, it finishes the circuit verification, parameteroptimization, simulation and layout design. The two modules proposed in the paperhave good performance and can be applied to the integrated RF transmitter on thechip.