Image signal transmission apparatus and signal output circuit having DC gain maintaining mechanism thereof

An image signal transmission apparatus used in an image signal transmission system, comprising:

• a digital signal processing circuit configured to generate a digital input signal;
• and
• a signal output circuit comprising:
• a front-stage driving circuit comprising a first CTLE having an adjusting capacitor and configured to receive the digital input signal to perform a high frequency enhancement thereon to increase a bandwidth of the digital input signal to generate a front-stage output signal;
• and
• a back-stage driving circuit comprising a second CTLE without the adjusting capacitor and configured to increase a DC gain of the front-stage output signal to compensate a DC gain drop between the front-stage output signal and the digital input signal to generate a back-stage output signal to an image signal receiving apparatus;
• wherein a DC gain of each of the front-stage driving circuit and the back-stage driving circuit cancels out each other when a multiplication result of a transconductance and a resistance of a load resistor of each of the front-stage driving circuit and the back-stage driving circuit is far larger than 1.