The circuit block diagram is shown below. From a single local-oscillator input (LO1), the phase shifter produces two LO signals with 90 phase separation and equal amplitude. The LO signals are fed to the in-phase (I) and quadrature (Q) double-balanced mixers. The resulting signals are summed and fed into an RF mixer where the frequency can be translated to over 2 GHz. Outputs between the summer and RF mixer are available for external filtering. Finally, the signal is amplified to provide a single-ended output.