阅读说明：本技术 一种低温度系数参考电流及电压产生电路 (Low-temperature coefficient reference current and voltage generating circuit ) 是由 梁思文 林满院 邱文才 田学红 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种低温度系数参考电流及电压产生电路。该低温度系数参考电流及电压产生电路,包括：自举电流镜、第一晶体管、第二晶体管和至少一个第三晶体管；自举电流镜包括控制信号输出端和参考电流输出端；第一晶体管的栅极连接控制信号输出端,第一晶体管的第一极与第一电源线电连接；第二晶体管的第一极连接参考电流输出端,第二晶体管的第二极连接第二电源线；至少一个第三晶体管串联于第一晶体管的第二极和第二晶体管的第一极之间,各第三晶体管的栅极和第二晶体管的栅极依次电连接,第一晶体管的第二极和第三晶体管的连接点作为参考电压输出端。本发明提供的低温度系数参考电流及电压产生电路,实现了对工艺依赖小,温度系数低的效果。(The invention discloses a low-temperature coefficient reference current and voltage generating circuit. The low temperature coefficient reference current and voltage generating circuit includes: a bootstrap current mirror, a first transistor, a second transistor, and at least one third transistor; the bootstrap current mirror comprises a control signal output end and a reference current output end; the grid electrode of the first transistor is connected with the control signal output end, and the first pole of the first transistor is electrically connected with the first power line; the first pole of the second transistor is connected with the reference current output end, and the second pole of the second transistor is connected with a second power line; at least one third transistor is connected in series between the second pole of the first transistor and the first pole of the second transistor, the grid electrode of each third transistor and the grid electrode of the second transistor are electrically connected in sequence, and the connection point of the second pole of the first transistor and the third transistor is used as a reference voltage output end. The low-temperature coefficient reference current and voltage generating circuit provided by the invention realizes the effects of small process dependence and low temperature coefficient.)

1. A low temperature coefficient reference current and voltage generating circuit, comprising:

a bootstrap current mirror including a control signal output and a reference current output;

a gate of the first transistor is connected to the control signal output terminal, and a first electrode of the first transistor is electrically connected to a first power line;

a second transistor, a first pole of which is connected to the reference current output terminal and a second pole of which is connected to a second power line;

and the at least one third transistor is connected between the second pole of the first transistor and the first pole of the second transistor in series, the grid electrode of each third transistor is electrically connected with the grid electrode of the second transistor in sequence, and the connection point of the second pole of the first transistor and the third transistor is used as a reference voltage output end.

2. The low temperature coefficient reference current and voltage generating circuit of claim 1 wherein said first transistor is a P-channel MOS transistor; the second transistor and the third transistor are N-channel MOS transistors.

3. The low temperature coefficient reference current and voltage generating circuit of claim 1 wherein the bootstrap current mirror further comprises:

a fourth transistor and a fifth transistor, a first pole of the fourth transistor and a first pole of the fifth transistor both being electrically connected to the first power supply line; the grid electrode of the fourth transistor and the grid electrode of the fifth transistor are both electrically connected with the second pole of the fourth transistor, and the connection point is used as the control signal output end;

at least one of a sixth transistor and a seventh transistor, a first terminal of the sixth transistor and a first terminal of the seventh transistor being electrically connected to a second terminal of the fourth transistor and a second terminal of the fifth transistor, respectively; a gate of the sixth transistor and a gate of the seventh transistor are both electrically connected to the first pole of the seventh transistor; a second pole of the sixth transistor is used as the reference current output end, and a second pole of the seventh transistor is connected with the second power line.

4. The low temperature coefficient reference current and voltage generating circuit of claim 3 wherein said fourth transistor and said fifth transistor are P-channel MOS transistors; the sixth transistor and the seventh transistor are N-channel MOS tubes.

5. The low temperature coefficient reference current and voltage generating circuit of claim 1, wherein the number of the third transistors is greater than or equal to 2.

6. The low temperature coefficient reference current and voltage generating circuit of claim 3, wherein the number of the sixth transistors is greater than or equal to 2.

7. The low temperature coefficient reference current and voltage generating circuit of claim 1 wherein the temperature coefficient of the forward on resistance of the second transistor is less than the temperature coefficient of a resistor of the same value.

8. The low temperature coefficient reference current and voltage generating circuit of claim 1, wherein the second power line is grounded.

Technical Field

The embodiment of the invention relates to the technology of analog integrated circuits, in particular to a low-temperature coefficient reference current and voltage generating circuit.

Background

The reference current generating circuit is an important component of an analog and mixed signal integrated circuit, and is widely applied to circuits such as a low dropout linear voltage regulator, a temperature sensor, a data converter, a radio frequency transceiver, a Flash memory and the like.

The reference current generating circuit is used as a 'quasi-rope' of the whole integrated circuit, the performance of the reference current generating circuit directly influences the performance of the circuit, and therefore the reference current generating circuit has good anti-interference capability. Taking the conventional bootstrap circuit as shown in fig. 1 as an example, such a MOS transistor current generation circuit based on threshold voltage has been proved to be usable as a reference current generation circuit, and can accommodate a lower supply voltage. For example, the simple reference voltage generating circuit shown in fig. 3 can generate reference voltages for various integrated circuits, but the implementation of the above circuit functions depends on process parameters to a large extent, and the generated reference current and voltage have large temperature coefficients, and cannot be used as the reference current and reference voltage of a high-performance analog circuit.

Disclosure of Invention

The invention provides a low-temperature coefficient reference current and voltage generating circuit, which realizes the effects of small process dependence and low temperature coefficient of the low-temperature coefficient reference current and voltage generating circuit.

The embodiment of the invention provides a low-temperature coefficient reference current and voltage generating circuit, which comprises: a bootstrap current mirror, a first transistor, a second transistor, and at least one third transistor; the bootstrap current mirror comprises a control signal output end and a reference current output end; the grid electrode of the first transistor is connected with the control signal output end, and the first pole of the first transistor is electrically connected with a first power line; a first pole of the second transistor is connected with the reference current output end, and a second pole of the second transistor is connected with a second power line; the at least one third transistor is connected in series between the second pole of the first transistor and the first pole of the second transistor, the grid electrode of each third transistor is electrically connected with the grid electrode of the second transistor in sequence, and the connection point of the second pole of the first transistor and the third transistor is used as a reference voltage output end.

Optionally, the first transistor is a P-channel MOS transistor; the second transistor and the third transistor are N-channel MOS transistors.

Optionally, the bootstrap current mirror further includes: a fourth transistor, a fifth transistor, at least one sixth transistor, and a seventh transistor; a first pole of the fourth transistor and a first pole of the fifth transistor are both electrically connected to the first power supply line; the grid electrode of the fourth transistor and the grid electrode of the fifth transistor are both electrically connected with the second pole of the fourth transistor, and the connection point is used as the control signal output end; a first terminal of the sixth transistor and a first terminal of the seventh transistor are electrically connected to a second terminal of the fourth transistor and a second terminal of the fifth transistor, respectively; a gate of the sixth transistor and a gate of the seventh transistor are both electrically connected to the first pole of the seventh transistor; a second pole of the sixth transistor is used as the reference current output end, and a second pole of the seventh transistor is connected with the second power line.

Optionally, the fourth transistor and the fifth transistor are P-channel MOS transistors; the sixth transistor and the seventh transistor are N-channel MOS tubes.

Optionally, the number of the third transistors is greater than or equal to 2.

Optionally, the number of the sixth transistors is greater than or equal to 2.

Optionally, a temperature coefficient of a forward on-resistance of the second transistor is smaller than a temperature coefficient of a resistor having the same resistance value.

Optionally, the second power line is grounded.

The reference current output end of the bootstrap current mirror is connected with the transistor with the lower temperature coefficient to reduce the temperature coefficient of the reference current, the reference current output end is used as one current input of the reference voltage circuit, and the reference voltage output end is designed at the first pole of the third transistor, so that the reference voltage value is added with the threshold voltage with the negative temperature coefficient to reduce the temperature coefficient of the reference voltage, the temperature coefficients of the reference current and the reference voltage are reduced under the condition of not increasing the circuit complexity, and the effects of small process dependence and low temperature coefficient of the low-temperature coefficient reference current and voltage generation circuit are achieved.

Drawings

FIG. 1 is a circuit diagram of a conventional bootstrap circuit in the prior art;

FIG. 2 is a circuit diagram of a simple reference voltage generating circuit in the prior art;

FIG. 3 is a schematic diagram of a low temperature coefficient reference current and voltage generating circuit according to an embodiment of the present invention;

FIG. 4 is a circuit diagram of another low temperature coefficient reference current and voltage generating circuit according to the present invention;

FIG. 5 is a trend graph of the reference current generated by the low temperature coefficient reference current and voltage generating circuit according to the present invention;

fig. 6 is a trend graph of the reference voltage generated by the low temperature coefficient reference current and voltage generating circuit according to the embodiment of the present invention along with the temperature variation.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

The embodiment of the invention provides a low-temperature coefficient reference current and voltage generating circuit 100. Fig. 3 is a schematic diagram of a low temperature coefficient reference current and voltage generating circuit 100 according to an embodiment of the present invention, referring to fig. 3, the circuit includes: a bootstrap current mirror 110, a first transistor M1, a second transistor M2, and at least one third transistor M3; the bootstrap current mirror 110 includes a control signal output terminal 120 and a reference current output terminal 130; the gate of the first transistor M1 is connected to the control signal output terminal 120, and the first pole of the first transistor M1 is electrically connected to the first power line VDD; a first pole of the second transistor M2 is connected to the reference current output terminal 130, and a second pole of the second transistor M2 is connected to the second power line V0; at least one third transistor M3 is connected in series between the second pole of the first transistor M1 and the first pole of the second transistor M2, the gate of each third transistor M3 is electrically connected to the gate of the second transistor M2 in turn, and the connection point between the second pole of the first transistor M1 and the third transistor M3 is used as the reference voltage output terminal 140.

The bootstrap current mirror 110 is a bootstrap circuit composed of current mirrors, and can generate a reference current; when the bootstrap current mirror 110 is turned on, the control signal output terminal 120 transmits a control signal to the gate of the first transistor M1 for controlling the on and off of the first transistor M1, and the on and off states of the first transistor M1 and the on and off states of the bootstrap current mirror 110 are kept consistent; the current flowing through the second pole of the first transistor M1 after the first transistor M1 is turned on is I₁(ii) a The reference current output terminal 130 is used for outputting the reference current I generated by the low temperature coefficient reference current and voltage generating circuit 100₂The reference voltage output terminal 140 is used for outputting the reference voltage generated by the low temperature coefficient reference current and voltage generating circuit 100; for example, the first transistor M1 is a P-channel MOS transistor, and the second transistor M2 and the third transistor M3 are both N-channel MOS transistors; the first power supply line VDD supplies a power supply voltage and the second power supply line V0 is grounded. Illustratively, when the bootstrap current mirror 110 is turned on by a voltage signal provided by the first power line VDD, the control signal output terminal 120 transmits a control signal to the gate of the first transistor M1, the control signal is smaller than the voltage signal provided by the first power line VDD, a voltage difference with the first power line VDD is larger than a turn-on threshold voltage of the first transistor M1, the first transistor M1 is turned on, and a current passing through the first transistor M1 is denoted as I₁At this time, the voltage signal is transmitted to the gates of the second transistor M2 and the third transistor M3, turning on the second transistor M2 and the third transistor M3; at the same time, the bootstrap current mirror 110 generates the reference current I₂Transmitted to the first pole of the second transistor M2 through the reference current output terminal 130 and flows through the second transistor M2 due to the equivalent resistance of the second transistor M2The temperature coefficient is smaller than the temperature coefficient of the resistor in the reference current generating circuit shown in fig. 1, so that the temperature coefficient of the reference current generated by the bootstrap current mirror 110 is reduced; on the other hand, if the current I passing through the first transistor M1 is to be passed₁Using reference current I₂Indicates, note as NI₂Then, the voltage V of the connection point of the reference current output terminal 130 and the first pole of the second transistor M2 is referenced_xCan be formulated asWherein the content of the first and second substances, i is the characteristic saturation current of the third transistor M3,is a thermal voltage, n is a slope factor, C_oxIs unit capacitance of gate oxide layer, S₃Is the width-to-length ratio, S, of the third transistor M3₂The width-to-length ratio of the second transistor M2, P, Q, M is a middle symbol, and V can be obtained from the above formula_xThe value of (A) is positively correlated with the thermoelectric voltage, which has a positive temperature coefficient, V_xWith a positive temperature coefficient, reference voltage V at output terminal 140_refIs equal to V_xPlus V_gsIn which V is_gsIs the voltage between the second pole and the gate of the third transistor M3, and V_gs＝V_th+V_ov，V_thIs the threshold voltage, V, of the third transistor M3_ovIs the over-driving voltage of the third transistor M3, wherein the over-driving voltage is the voltage between the second pole and the gate of the third transistor M3 reaching the threshold voltage V_thThen, the increased voltage value continues, because the threshold voltage of the MOS transistor itself has a negative temperature coefficient, i.e. the threshold voltage Vth of the third transistor M3 has a negative temperature coefficient, so the voltage V at the reference voltage output terminal 140_refTemperature coefficient of less than V_xTemperature coefficient of。

It should be noted that, in the conventional bootstrap circuit as shown in the background art of fig. 1, the reference current output terminal is connected to a resistor, which has a higher temperature coefficient, so that the temperature coefficient of the generated reference current is higher, whereas in the present invention, the reference current output terminal is connected to a transistor having a smaller temperature coefficient, which greatly reduces the temperature coefficient of the generated reference current; in the simple reference voltage generating circuit shown in fig. 2, the connection point x of the first pole and the second pole of the two transistors is generally used as the reference voltage output terminal, and the temperature coefficient of this point is positive, whereas in the embodiment of the present invention, the reference voltage output terminal is the first pole of the third transistor M3, and the voltage of this point is the voltage of the connection point of the second pole of the third transistor M3 and the second pole of the second transistor M2 plus the voltage difference V between the second pole and the gate of the third transistor M3_gsThis voltage difference V_gsThe temperature is inversely related, and the design not only increases the output reference voltage, but also reduces the temperature coefficient of the reference voltage.

The low temperature coefficient reference current and voltage generating circuit provided by this embodiment reduces the temperature coefficient of the reference current by connecting the reference current output terminal of the bootstrap current mirror with the transistor having a lower temperature coefficient, and designs the reference voltage output terminal at the first pole of the third transistor by using the reference current output terminal as a current input of the reference voltage circuit, so that the threshold voltage of the negative temperature coefficient is added to the reference voltage value to reduce the temperature coefficient of the reference voltage, and the temperature coefficients of the reference current and the reference voltage are reduced without increasing the circuit complexity, thereby achieving the effects of the low temperature coefficient reference current and voltage generating circuit, such as small process dependence and low temperature coefficient.

Fig. 2 is a circuit diagram of another low temperature coefficient reference current and voltage generating circuit 100 provided in the present invention, and optionally, the bootstrap current mirror 110 further includes: a fourth transistor M4, a fifth transistor M5, at least one sixth transistor M6, and a seventh transistor M7; a first pole of the fourth transistor M4 and a first pole of the fifth transistor M5 are both electrically connected to the first power supply line VDD; the gate of the fourth transistor M4 and the gate of the fifth transistor M5 are both electrically connected to the second pole of the fourth transistor M4, and the connection point is used as the control signal output terminal 120; a first terminal of the sixth transistor M6 and a first terminal of the seventh transistor M7 are electrically connected to a second terminal of the fourth transistor M4 and a second terminal of the fifth transistor M5, respectively; the gate of the sixth transistor M6 and the gate of the seventh transistor M7 are both electrically connected to the first pole of the seventh transistor M7; a second pole of the sixth transistor M6 is used as the reference current output terminal 130, and a second pole of the seventh transistor M7 is connected to the second power line V0.

The fourth transistor M4 and the fifth transistor M5 form a current mirror, and the gate of the first transistor M1 is connected to the gate of the fourth transistor M4 and the gate of the fifth transistor M5, that is, the gate of the fourth transistor M4 is used as a control signal output terminal. In addition, since the first electrode of the first transistor M1 is connected to the first power line VDD like the fourth transistor M4, the first transistor M1 is also turned on in a mirror image manner while the fourth transistor M4 and the fifth transistor M5 are turned on; the sixth transistor M6 and the seventh transistor M7 form a current mirror; the fourth transistor M4 and the fifth transistor M5 are both P-channel MOS transistors, and the sixth transistor M6 and the seventh transistor M7 are both N-channel MOS transistors; the number of the sixth transistors M6 is increased, since each of the sixth transistors M6 is turned on in a mirror image manner, and the second terminals of the sixth transistors M6 are electrically connected, the reference current I is increased₂Is equal to the sum of the second pole currents of the respective sixth transistors M6, so that the reference current I₂The larger the value of (d) will be with the increase in the number of sixth transistors M6; similarly, the number of the third transistors M3 is increased, and since the gates of the third transistors M3 are electrically connected, the third transistors M3 are turned on simultaneously, and the voltage Vref at the reference voltage output terminal 140 is V_xPlus the gate-source voltage V of each third transistor M3_gsTherefore, the value of the voltage Vref at the reference voltage output terminal 140 increases as the number of the third transistors M3 increases. .

Illustratively, the number of the sixth transistors M6 is 1, the number of the third transistors M3 is 2, when the voltage signal provided by the first power line VDD is transmitted to the first pole of the fourth transistor M4, and the gate and the second pole of the fourth transistor M4 are biasedWhen the difference is larger than the threshold voltage, the fourth transistor M4 is turned on, since the fourth transistor M4 and the fifth transistor M5 form a current mirror, the fifth transistor M5 is turned on simultaneously, the voltage signal is transmitted to the gates of the sixth transistor M6 and the seventh transistor M7, the two sixth transistor M6 and the seventh transistor M7 are turned on, and the reference current I2 flows to the first pole of the second transistor M2 through the reference current output terminal 130; on the other hand, since the gate of the first transistor M1 is connected to the gate of the fourth transistor M4 and the gate of the fifth transistor M5 through the control signal output terminal 120, the first transistor M1 is turned on while the fourth transistor M4 and the fifth transistor M5 are turned on, and the current through the first transistor M1 is denoted as I₁At this time, the voltage signal is transmitted to the gates of the second transistor M2 and the third transistor M3, turning on the second transistor M2 and the third transistor M3; i1 and I2 flow through the second transistor M2, and since the temperature coefficient of the equivalent resistance of the second transistor M2 is smaller than that of the resistance in the reference current generating circuit shown in fig. 1, the temperature coefficient of the reference current generated by the bootstrap current mirror 110 is reduced; in addition, the connection point of the first pole of the third transistor M3 and the second pole of the first transistor M1 is used as the reference voltage output end 140, the voltage Vref of the reference voltage output end 140 is greater than the voltage of the reference voltage output end 140 of the 1-transistor circuit of the third transistors M3, and is equal to Vx plus 2Vgs, where Vgs is the voltage difference between the second pole and the gate of the third transistor M3, and is Vth + Vov, Vth is the threshold voltage of the third transistor M3, and Vov is the overdrive voltage of the third transistor M3, because the threshold voltage of the MOS transistor itself has a negative temperature coefficient, that is, Vth has a negative temperature coefficient, the temperature coefficient of the voltage Vref of the reference voltage output end 140 is less than the temperature coefficient of Vx.

Fig. 5 is a trend graph of the reference current generated by the low temperature coefficient reference current and voltage generating circuit 100 according to the embodiment of the present invention, as shown in fig. 5, the reference current has a small change with the change of the temperature, especially, the change rate of the reference current reaches the minimum value between 0 ℃ and 30 ℃, and approaches to 0; fig. 6 is a trend graph of the reference voltage generated by the low temperature coefficient reference current and voltage generating circuit 100 according to the embodiment of the present invention, as shown in fig. 6, the reference voltage generated by the low temperature coefficient reference current and voltage generating circuit has a smaller change with temperature.

In the low temperature coefficient reference current and voltage generating circuit provided by this embodiment, the temperature coefficient of the reference current is reduced by connecting the reference current output end of the bootstrap current mirror with the transistor with a lower temperature coefficient, and the reference voltage output end is designed at the first pole of the third transistor by using the reference current output end as a current input of the reference voltage circuit, so that the threshold voltage of the negative temperature coefficient is added to the reference voltage value, that is, the value of the reference voltage is increased and the temperature coefficient of the reference voltage is also reduced, the temperature coefficients of the reference current and the reference voltage are reduced under the condition of not increasing the circuit complexity, and the effects that the low temperature coefficient reference current and voltage generating circuit has little dependence on the process and a low temperature coefficient are achieved.

Optionally, the first transistor is a P-channel MOS transistor; the second transistor and the third transistor are N-channel MOS transistors.

Optionally, the fourth transistor and the fifth transistor are P-channel MOS transistors; the sixth transistor and the seventh transistor are N-channel MOS transistors.

Optionally, the number of the third transistors is greater than or equal to 2.

The more the number of the third transistors is, the larger the reference voltage value output by the low-temperature coefficient reference current and voltage generation circuit is.

The low-temperature coefficient reference current and voltage generating circuit provided by the embodiment increases the values of the reference voltage and the reference current without increasing the circuit complexity, reduces the temperature coefficients of the reference current and the reference voltage, and achieves the effects that the low-temperature coefficient reference current and voltage generating circuit has small dependence on the process and has a low temperature coefficient.

Optionally, the number of sixth transistors is greater than or equal to 2.

The larger the number of the sixth transistors is, the larger the value of the low-temperature coefficient reference current and the reference current output by the voltage generation circuit is.

Optionally, the temperature coefficient of the forward on-resistance of the second transistor is smaller than that of the resistor with the same resistance value.

According to the low-temperature coefficient reference current and voltage generating circuit provided by the embodiment, the MOS tube is used for replacing a resistor in a traditional reference current generating circuit, the values of the reference voltage and the reference current are increased under the condition that the complexity of the circuit is not increased, the temperature coefficients of the reference current and the reference voltage are also reduced, and the effects that the low-temperature coefficient reference current and voltage generating circuit is small in process dependence and low in temperature coefficient are achieved.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments illustrated herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.