The present invention relates to the field of electrical
signal transmission, and discloses a two-
wire protocol sending circuit and a two-wire
transmitter. The circuit includes: a first
amplifier, a
resistor, a first
transistor, and a second
transistor; the positive input terminal of the first
amplifier is connected to the first end of the
resistor, the second end of the
resistor is grounded, the output terminal of the first
amplifier is respectively connected to the first ends of the first
transistor and the second transistor, the second end of the first transistor is connected to the first end of the resistor, the third end and the second end of the second transistor are respectively connected to a receiving unit through the positive terminal and the negative terminal of an external loop, and the third end of the first transistor, the third end of the second transistor, and the power supply terminal of the first amplifier are all connected to the
power supply voltage terminal of the circuit; by adjusting the ratio of the number of the second transistor to the first transistor, a control current
signal of 4-20 mA is controlled to be output by the circuit, and compared with the control method and circuit structure of a traditional typical circuit, it is simpler, reduces the
chip area, and is beneficial to reducing the
chip manufacturing process cost.