Mixer with common-mode noise rejection

A method of mixing a plurality of video input signals into a video output signal comprising the steps of:

• a. receiving the plurality of video input signals and respective ground reference signals;
• b. generating a plurality of differential signals each representative of a difference between one of the video input signals and a corresponding respective ground reference signal;
• and
• c. generating the video output signal including a predetermined ratio of the plurality of differential signals.

A video mixer circuit for receiving a first input video signal and a corresponding first ground reference signal and a second input video signal and a corresponding second ground reference signal and combining the first and second input video signals into an output video signal comprising:

• a. a first transconductance amplifier stage configured for receiving the first input video signal and the corresponding first ground reference signal and generating a differential signal representative of a difference between the first input video signal and the first ground reference signal;
• b. a second transconductance amplifier stage configured for receiving the second input video signal and the corresponding second ground reference signal and generating a second differential signal representative of a difference between the second input video signal and the second ground reference signal;
• and
• c. a mixing circuit coupled to receive the first differential signal and the second differential signal for generating the output video signal including a predetermined ratio of the first and second differential signals.

A video display system for receiving video input signals and generating an output composite video signal comprising:

• a. an analog input video receiving circuit configured for receiving an analog input signal and an analog ground reference signal and generating an analog differential signal representative of a difference between the analog input signal and the analog ground reference signal;
• b. a digital input video receiving circuit configured for receiving a digital input signal and a digital ground reference signal and generating a digital differential signal representative of a difference between the digital input signal and the digital ground reference signal;
• and
• c. a mixing circuit configured for receiving an analog content signal representing a percentage of the output composite video signal which is to include the analog differential signal and for receiving a digital content signal representing a percentage of the output composite video signal which is to include the digital differential signal and coupled to receive the analog differential signal and the digital differential signal for combining the analog and digital differential signals in a predetermined ratio specified by the analog and digital content signals, respectively, into the output composite video signal.