Signal generating device, bandgap reference device and method of generating temperature-dependent signal

A bandgap reference device, comprising:

• a first circuit, coupled between a first reference voltage, a ground terminal and an output terminal, and arranged to generate a first current to a first bipolar junction transistor (BJT) therein;
• a second circuit, coupled to the output terminal;
• a third circuit, coupled to the output terminal, for generating a bandgap reference voltage, and the third circuit comprises a resistor coupled between the first reference voltage and the ground terminal;
• and
• a control circuit, coupled to the first BJT and the second circuit and arranged to adjust the first current such that the first circuit outputs a part of a temperature-dependent signal on the output terminal;
• wherein the first circuit comprises:
• a first field-effect transistor (FET), having a first connecting terminal coupled to the first reference voltage, a control terminal coupled to the output terminal;
• a second FET, having a first connecting terminal coupled to a second connecting terminal of the first FET, a control terminal coupled to the first connecting terminal of the second FET;
• and
• the first BJT, having a first terminal coupled to a second connecting terminal of the second FET, a second terminal coupled to a first base signal and a third terminal coupled to the ground terminal;
• wherein the control circuit comprises:
• a first active device, having a first connecting terminal coupled to the first BJT, a second connecting terminal coupled to the first BJT;
• a second active device, having a first connecting terminal coupled to the first BJT, a second connecting terminal coupled to the ground terminal, and a control terminal coupled to the second circuit;
• an amplifier, having an input terminal coupled to the first BJT and an output terminal coupled to the control terminal of the first active device.

A method of generating a temperature-dependent signal, comprising:

• arranging a first circuit to generate a first current to a first bipolar junction transistor (BJT) formed therein;
• adjusting the first current;
• outputting a temperature-dependent signal on an output terminal;
• and
• arranging a control circuit coupled to the first circuit to control the temperature-dependent signal according to the first current;
• wherein adjusting the first current comprises:
• arranging a first field-effect transistor (FET) which is free from connecting to a ground terminal directly;
• and
• arranging an amplifier to control the first FET according to a first signal from the first BJT;
• arranging a second circuit to generate a second current to a second BJT formed therein, wherein the second circuit is coupled to the first circuit via the output terminal;
• and
• adjusting the second current;
• wherein adjusting the second current comprises:
• arranging a second FET which is free from connecting to a ground terminal directly;
• and
• arranging the amplifier to control the second FET according to a second signal from the second BJT.