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Quadrature modulators and demodulators are widely used to create modern wireless communication systems. It is crucial to ensure the high quality of the transmitted signals for the exchange of information takes place without loss or failure. From the point of view of the spectral decomposition of the signal (Fourier series decomposition), the useful component of the spectrum must be much larger than other components. The most critical undesirable quadrature modulator output signal spectral components are a carrier (LO frequency) and spurious sideband. In the course of the research, using computer simulation, methods of their suppression were identified, based on minimizing phase, amplitude, and current imbalances in various nodes of the quadrature modulator circuit. The effectiveness of methods is confirmed by the achievement of suppression of parasitic components in prototypes of 50 dB or more.

The broadband quadrature modulators/demodulators are used in communication systems, satellites, cellular, locators, wi-fi systems and other commercial circuits. In the article, the development of high-speed quadrature modulator and demodulator with embedded digital correction circuit by BiCMOS 180 nm technology is presented. The control block uses sequential data loading interface with 3 control inputs. Mixer core, polyphase filter, and digital correction circuits are considered in the paper. The article presents topologies of quadrature modulator, demodulator with frequency range 1800 MHz to 6 GHz, modulation bandwidth 700 MHz and 8 dBm input P1dB. Power consumption is less than 1000 mW.