CN101382811A - Current Source Stabilization Circuit - Google Patents

Abstract

The present invention is a current source stabilizing circuit for stabilizing a current value outputted by a current source under a temperature change condition, the current value of the current source increasing with a temperature increase, the current source stabilizing circuit comprising: a current source circuit for providing a current that rises with increasing temperature; a correction circuit, coupled to the current source circuit, for providing an input current, which rises with increasing temperature; the current of the current source circuit is subtracted from the input current to form a current source current, and the current source current does not change along with temperature change. The current source stabilizing circuit can effectively save cost and hardware space.

Description

Current Source Stabilization Circuit

technical field

The present invention relates to a current source stabilizing circuit, in particular to a current source stabilizing circuit used for stabilizing a current source whose current increases with temperature.

Background technique

In the design of integrated circuits, some reference voltages and reference currents are often required, and the reference voltages and reference currents are usually included in the bias voltage part of the entire integrated circuit. In general applications, these bias voltages are usually designed based on the operating temperature of the circuit, without special consideration of the relationship with temperature changes.

However, in fact, when the circuit is working, the temperature of the circuit is often changed due to the change of the ambient temperature or the heat generated by the electronic components in the circuit. The temperature change may affect the circuit application when the signal is converted, making the converted signal with Noise with temperature effects, such as analog-to-digital converters are affected by temperature noise. In addition, the micro-processing system with sensors is also sensitive to temperature changes, and temperature changes will also affect the operation of such electronic circuits.

It is generally used to generate circuits related to temperature changes, and bipolar junction transistors (Bipolar Junction Transistor; BJT) are usually used. However, the base and emitter voltage (V _BE ) of the BJT has a logarithm with the collector current relationship and is affected by temperature changes. The relationship between V _BE and temperature can be expressed as V _BE (H, I _C )=E _GE -H(E _GE -V _BEN )+V _TN Hlog(I _C / _IN )-ηV _TN HlogH, where H=T/ T _N , T is the absolute temperature, and T _N is the normalized temperature, usually T _N will take the middle value of the temperature range in which the circuit works, usually 300K (27°C). E _GE represents the assumed value of V _BE at absolute zero, approximately between 1.14V and 1.19V. V _BEN is the value of V _BE when the transistor junction temperature is at a specific _TN and _IC is equal to a specific _IN . V _TN is the value of the thermal voltage V _T =kT/q at normalized temperature. η is a constant of the curve, approximately between 2 and 4.

Please refer to Figure 1, Figure 1 is the performance of the description equation V _BE (H, I _C )=E _GE -H(E _GE -V _BEN )+V _TN Hlog(I _C /I _N )-ηV _TN HlogH, as shown in the figure 1, when the temperature T rises, V _BE drops. And when _IC increases (increasing), V _BE increases. This is the characteristic of the BJT circuit, and the BJT is usually used in a circuit in which the current increases as the temperature rises to balance the current and keep the current at a certain value as much as possible.

However, due to the need to use diodes, BJT circuits consume high hardware costs and occupy a large hardware space, which inevitably consumes them in use. Therefore, how to develop a new current source stabilization method has become an urgent need. A problem that needs to be solved.

Contents of the invention

Therefore, one of the objects of the present invention is to provide a method for stabilizing a current source, which is used to stabilize a current value output by a current source when the temperature changes, and the current value of the current source will increase with temperature and rise, the method includes: providing a correction circuit, an output current of the circuit rises with temperature, and a coefficient of the current rise with temperature and a coefficient of the current source rise with temperature Equal; provide a connection method, so that the current value of the current source is subtracted from the output current before output; wherein, after the current value of the current source is subtracted from the output current, when the current value of the current source is output Does not change with temperature.

The present invention also provides a current source stabilizing circuit, which is used to stabilize a current value output by a current source when the temperature changes. The current value of the current source will increase as the temperature increases, and the current source is stable. The circuit includes: a current source circuit, which is used to provide a current, and the current increases with temperature; a correction circuit, coupled to the current source circuit, is used to provide an input current, and the input current increases with temperature and rise; wherein, the current of the current source circuit is subtracted from the input current to become a current source current, and the current source current does not change with temperature.

In the current source stabilizing circuit of the present invention, the current of the current source circuit is the same as the coefficient of the input current rising with temperature.

According to the current source stabilizing circuit of the present invention, the current source circuit is a self-biased metal oxide semiconductor field effect transistor voltage reference current source.

In the current source stabilizing circuit of the present invention, the correction circuit is a start-up circuit.

In the current source stabilizing circuit of the present invention, the correction circuit is mainly composed of a plurality of metal oxide semiconductors.

In the current source stabilizing circuit of the present invention, by adjusting the number of the plurality of metal oxide semiconductors in the correction circuit, the coefficient of the increase of the input current as the temperature rises is adjusted.

In the current source stabilizing circuit of the present invention, the correction circuit does not include a diode.

The current source stabilizing circuit of the present invention can effectively save cost and hardware space.

Description of drawings

Fig. 1 is a representation describing the equation V _BE (H, I _C )=E _GE -H(E _GE -V _BEN )+V _TN Hlog(I _C / _IN )-ηV _TN HlogH.

FIG. 2 is a structure diagram of a current source stabilization circuit in a preferred embodiment of the present invention.

Fig. 3 is a schematic diagram showing the current value processing of the present invention.

Detailed ways

Please refer to Fig. 2, Fig. 2 is the structural diagram of the current source stabilizing circuit of the preferred embodiment of the present invention, as shown in Fig. 2, the current source stabilizing circuit 2 comprises a current source circuit 21 and a correction circuit 22, and the current source circuit 21 comprises A first PMOS (P-type metal oxide semiconductor) 211 , a first NMOS (N-type metal oxide semiconductor) 212 , a first resistor 213 , a second PMOS 214 , a second NMOS 215 and a ground terminal 216 .

The correction circuit 22 includes a third NMOS 221 , a fourth NMOS 222 , a fifth NMOS 223 and a sixth NMOS 224 .

The source of the first PMOS 211 is coupled to the sources of the second PMOS 214 and the third NMOS 221 , the gate is coupled to the gate of the second PMOS 214 , and the drain is coupled to the source of the first NMOS 212 . The gate of the first NMOS212 is coupled to the drain of the second PMOS214 and the source of the second NMOS215, the drain is coupled to one end of the first resistor 213 and the gate of the second NMOS215, and the other end of the first resistor 213 is coupled to Connect to the ground terminal 216.

The drain of the second PMOS 214 is coupled to the source of the second NMOS 215 and the drain of the fifth NMOS 223 and the source of the sixth NMOS 224 . The drain of the second NMOS 215 is coupled to the ground terminal 216 .

The drain of the third NMOS221 is coupled to the source of the fourth NMOS222, the drain of the fourth NMOS222 is coupled to the source of the fifth NMOS223, the drain of the fifth NMOS223 is coupled to the source of the sixth NMOS224, and the sixth The drain of the NMOS 224 is coupled to the ground terminal 216 , the gate of the fifth NMOS 223 is interconnected with the gate of the sixth NMOS 224 , and is coupled to the sources of the third NMOS 221 , the second PMOS 214 and the first PMOS 211 .

Wherein the current source circuit 21 may be a self-biasing MOSFET Vt reference current source for providing a current as a current source, and the correction circuit 22 may be a startup circuit (start up ), provide the input current, use the energy band (bandgap) reference voltage mode, use the characteristic that the input current generated by the correction circuit 22 rises as the temperature increases, subtract the current of the current source circuit 21 from the input current before the input . Since multiple MOSs in the correction circuit 22 can use the method of increasing or decreasing the MOS to change the temperature coefficient of the current, the coefficient of the increase of the input current as the temperature increases is adjusted to be the same as the coefficient of the increase of the current supplied by the current source circuit 21 as the temperature increases. , so after the current value provided by the current source circuit 21 is subtracted from the input current value, the output current will become a stable current value, which will not increase due to the increase of temperature, nor will it decrease due to the decrease of temperature , When the output current is eliminated, the temperature instability factor becomes a more stable current source circuit.

Please refer to FIG. 3 again, which shows a schematic diagram of the current value processing of the present invention. As shown in the third figure, the relationship between the current value generated by the current source circuit 21 and the temperature is shown in the relationship diagram 31, and the input current value generated by the correction circuit 22 and temperature as shown in the relationship diagram 32, wherein the horizontal axis is the temperature, and the vertical axis is the current value. The slopes of the curves are the same, so after subtracting them, the relationship between the current value output by the current source stabilization circuit 2 and the temperature is shown in Figure 33. In the relationship Figure 33, the current value does not change with the temperature, but becomes a constant value .

The correcting circuit 22 of the present invention is a start-up circuit composed of four NMOSs in the preferred embodiment, but it is not limited thereto, and the current source circuit is not limited to a self-biased metal oxide field effect voltage reference current source.

Since the present invention does not use the traditional BJT circuit, it does not use the diode commonly used in the BJT circuit, which can effectively save cost and hardware space.

The above description is only a preferred embodiment of the present invention, but it is not intended to limit the scope of the present invention. Any person familiar with this technology can make further improvements on this basis without departing from the spirit and scope of the present invention. Improvements and changes, so the protection scope of the present invention should be defined by the claims of the present application.

A brief description of the symbols in the drawings is as follows:

2: Current source stabilization circuit

21: Current source circuit

211: First PMOS

212: First NMOS

213: first resistance

214: Second PMOS

215: Second NMOS

216: Ground terminal

22: Correction circuit

221: Third NMOS

222: Fourth NMOS

223: Fifth NMOS

224: Sixth NMOS

31: The relationship between the current value and temperature generated by the current source circuit 21

32: The relationship between the input current value and temperature generated by the correction circuit 22

33: The relationship between the current value output by the current source stabilization circuit 2 and the temperature

Claims (7)

1. A current source stabilizing circuit, characterized in that it is used to stabilize a current value output by a current source under the condition of temperature changes, the current value of the current source will increase with temperature, and the current Source stabilization circuitry includes: a current source circuit for providing a current that increases with temperature; a correction circuit, coupled to the current source circuit, for providing an input current that increases with temperature; Wherein, the current of the current source circuit is subtracted from the input current to become a current source current, and the current source current does not change with temperature. 2 . The current source stabilizing circuit according to claim 1 , wherein the current of the current source circuit and the input current have the same coefficient of increasing temperature. 3 . 3. The current source stabilizing circuit according to claim 1, wherein the current source circuit is a self-biased MOSFET voltage reference current source. 4. The current source stabilizing circuit according to claim 1, wherein the correction circuit is a start-up circuit. 5. The current source stabilizing circuit according to claim 1, wherein the correction circuit is mainly composed of a plurality of metal oxide semiconductors. 6 . The current source stabilizing circuit according to claim 5 , wherein the coefficient of the input current rising with temperature is adjusted by adjusting the number of the plurality of metal oxide semiconductors in the correction circuit. 7 . 7. The current source stabilizing circuit according to claim 1, wherein the correction circuit does not include a diode.

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