Double Sideband With Suppressed Carrier 

The diagram above shows how to generate a double sideband signal with suppressed carrier. Its generating both the lower and upper sidebands simultaneously without any carrier. Later in the examples you will see how to generate the lower or upper sideband on its own. If you wanted to generate SSB from this signal it would require a additional sideband filter. 

The circuit has two multipliers which are supplied with a quadrature LO signal. The modulation signal is applied to both multipliers with the same phase. The signal from the two multipliers are then sum together to form the DSB signal.

This could be realized for example by using a couple of SBL1 mixers and a combiner to add the signals together to generate the DSB signal.

Generating The Lower Sideband

To generate a single sideband signal the modulation signal needs to be applied to the multipliers in quadrature. To produce the lower sideband the signal phases need to be the same for both the modulation and local oscillator when applied to the multiplier. In the example above MOD 1 and LO1 are in phase and MOD 2 and LO2 are in quadrature with respect to MOD1 and LO1.  

Generating The Upper Sideband

To produce the upper sideband the signal phase of the modulation signal needs to be swapped over. In the example above MOD 1 and LO1 are in quadrature phase and MOD 2 and LO2 are in quadrature.