Mixer Linearization by Modified Baseband Signals

In this paper, the linearization of the Gilbert downconverter mixer at the receiver is performed by two different methods that exploit the modified baseband signals. The signals for linearization in both methods are formed and processed in digital domain after demodulation. In the first method, the modified baseband signal is adjusted in amplitude and polarity and injected at the mixer. The linearization signals in the second method, which are also formed in the baseband and set on the appropriate amplitude and phase, modulate the fundamental carrier second harmonic and then lead to the mixer. The linearization effects of the linearization methods on the thirdand fifth-order intermodulation products are compared for the case when the signals for linearization are driven at the transistors’ drain of the RF stage differential pair in the Gilbert cell. The influence of the linearization signals delay on the results is analysed as well.