Transmission circuit, transmission method and transmission and reception system

A transmission and reception system, comprising:

• a transmission circuit, comprising:
• an output stage circuit, comprising:
• a variable output impedance circuit, coupled to a positive terminal channel and a negative terminal channel;
• and
• a driving circuit, comprising a positive output terminal and a negative output terminal, configured to output a second data signal through the variable output impedance circuit according to a first data signal, wherein the positive output terminal and the negative output terminal drive the positive terminal channel and the negative terminal channel respectively through the variable output impedance circuit;
• and
• a transition detection circuit, coupled to the output stage circuit, configured to detect whether the first data signal transitions from a logic high state to a logic low state, or from the logic low state to the logic high state according to a clock signal having a time period, and generate a detection result to adjust the variable output impedance circuit;
• wherein the variable output impedance circuit comprises a matching resistor and a first switch, the matching resistor and the first switch are coupled in series between the positive terminal channel and the negative terminal channel, the transition detection circuit controls the first switch to be turned on or turned off according to the detection result;
• when the detection result indicates that the first data signal transitions from the logic high state to the logic low state, or from the logic low state to the logic high state, the first switch is turned on;
• and
• when the detection result indicates that the first data signal does not transition from the logic high state to the logic low state, or from the logic low state to the logic high state, the first switch is turned off;
• a reception circuit, configured to receive a third data signal;
• and
• a channel, comprising the positive terminal channel and the negative terminal channel, coupled between the transmission circuit and the reception circuit, configured to transmit the second data signal output by the variable impedance circuit of the transmission circuit to the reception circuit as the third data signal through the channel.

A transmission method, for a transmission circuit, wherein the transmission circuit transmits signals to a reception circuit through a positive terminal channel and a negative terminal channel, the transmission method comprising:

• receiving a first data signal and a clock signal having a time period;
• detecting whether the first data signal transitions from a logic high state to a logic low state, or from the logic low state to the logic high state and generating a detection result according to the clock signal;
• adjusting characteristics of the transmission circuit according to the detection result;
• and
• outputting a second data signal according to the first data signal, and transmitting the second data signal to the reception circuit as a third data signal through the positive terminal channel and the negative terminal channel:
• wherein the step of adjusting the characteristics of the transmission circuit according to the detection result comprises:
• when the detection result indicates that the first data signal transitions from the logic high state to the logic low state, or from the logic low state to the logic high state, adjusting an equivalent output impedance of the transmission circuit, to achieve impedance matching of the transmission circuit, the positive terminal channel, the negative terminal channel and the reception circuit;
• and
• when the detection result indicates that the first data signal does not transition from the logic high state to the logic low state, or from the logic low state to the logic high state, decreasing a driving current of the transmission circuit.