Signal-to-noise optimized fully monolithic video receiver IF channel

A method of processing radio frequency (RF) signals, the method comprising the steps of:

• receiving an input RF signal;
• mixing said input RF signal with an operating frequency signal to generate a first signal;
• filtering said first signal to generate a second signal, wherein said filtering said first signal includes processing said first signal through a low-pass filter;
• amplifying to a fixed level said second signal to generate a third signal, wherein said amplifying said second signal to generate a third signal includes amplifying said second signal by a variable gain amplifier (VGA), the limit of said VGA being the maximum level acceptable by said third signal filtering step without distortion;
• filtering said third signal to generate a fourth signal;
• and
• amplifying said fourth signal a fixed amount to generate a fifth signal;
• wherein said mixing, filtering and amplifying steps are performed on a single integrated circuit substrate.

A radio frequency (RF) signal processing circuit comprising:

• a mixer coupled to an RF signal input;
• a variable gain amplifier coupled to said mixer, wherein said variable gain amplifier amplifies IF signals received from said mixer to a particular signal level, said particular signal level corresponding to the maximum signal level that can be accepted by a filter without distorting said RF signal;
• said filter coupled to an output of said variable gain amplifier and operable to pass frequencies in a selected IF band, while simultaneously attenuating signals having frequencies outside of said IF band;
• and
• an amplifier coupled to an output of said filter;
• wherein said mixer, said filter, and said amplifiers are physically located on a single integrated circuit substrate.

The method of processing an RF signal comprising the steps of:

• inputting said RF signal to a mixer;
• mixing said RF signal to create an intermediate frequency (IF) signal;
• filtering said IF signal to remove high frequency signals, thereby creating a first filtered IF signal;
• amplifying said first filtered IF signal to a selected signal level, thereby generating an amplified, first filtered IF signal, said selected signal level corresponding to the maximum level acceptable as an input to a band-pass filter to avoid distortion of said signal;
• filtering said amplified, first filtered IF signal in said band-pass filter, wherein said band-pass filter attenuates signals having frequencies above and below an IF frequency band, thereby generating a second filtered IF signal;
• and
• amplifying said second filtered IF signal;
• wherein said mixing step, said filtering steps, and said amplifying steps are conducted in circuits that are physically located on a single integrated circuit substrate.