Bandgap reference circuit

Abstract

Provided herein is a bandgap reference circuit comprising: a proportional to absolute temperature (PTAT) voltage circuit configured to generate a PTAT voltage; and a bandgap voltage circuit comprising a diode, the bandgap voltage circuit configured to: receive the PTAT voltage from the PTAT voltage circuit; and combining the PTAT voltage with a diode voltage across the diode to output a bandgap reference voltage.

Description

Technical Field

[0001] This disclosure relates to a bandgap reference circuit. Background Technology

[0002] Bandgap reference circuits built using bipolar transistors are commonly used in Brokaw or Banba configurations to construct bandgap reference voltages. Bipolar transistors are known to generate electromagnetic interference (EMI) problems because their collectors are exposed to the substrate / disposal wafer. To avoid bipolarity, simple PN diodes are typically used in Banba architectures to achieve a constant reference voltage / current. However, using PN diodes in Banba architectures results in large area and high noise. Summary of the Invention

[0003] According to a first aspect of this disclosure, a bandgap reference circuit is provided, comprising:

[0004] A PTAT voltage circuit proportional to absolute temperature, configured to generate a PTAT voltage; and

[0005] A bandgap voltage circuit, including a diode, is configured to:

[0006] Receive the PTAT voltage from the PTAT voltage circuit; and

[0007] The PTAT voltage is combined with the diode voltage across the diode to output a bandgap reference voltage.

[0008] In one or more embodiments, the bandgap voltage circuit may include:

[0009] A bandgap voltage node configured to output the bandgap reference voltage; and

[0010] The tail voltage node is configured to be set to the PTAT voltage.

[0011] The anode of the diode is connected to the bandgap voltage node, and the cathode of the diode is connected to the tail voltage node.

[0012] In one or more embodiments, the bandgap voltage circuit may include:

[0013] A regulating transistor having a source terminal coupled to a power supply voltage node and a drain terminal connected to the bandgap voltage node;

[0014] An input circuit, coupled to the PTAT voltage circuit, and configured to set the tail voltage node to the PTAT voltage; and

[0015] The current mirror output transistor has a conductive channel connected between the tail voltage node and the reference voltage node.

[0016] [The PTAT voltage circuit is configured to generate the PTAT voltage from the power supply voltage received at the power supply voltage node; and]

[0017] In one or more embodiments, the input circuit may include:

[0018] A first input transistor, wherein the source terminal of the first input transistor is connected to the power supply node, and the drain terminal of the first input transistor is connected to the gate terminal of the regulating transistor; and

[0019] A second input transistor, wherein the drain terminal of the second input transistor is connected to the gate terminal of the regulating transistor, and the source terminal of the second input transistor is connected to the tail voltage node.

[0020] The first and second input transistors can form a current mirror output. The input circuit can mirror the PTAT current from the PTAT voltage circuit. The input circuit can mirror the PTAT voltage from the PTAT voltage circuit to the tail voltage node. The gate of each of the first and second input transistors can be connected to a corresponding terminal of the PTAT voltage circuit.

[0021] The regulating transistor, the diode, and the first and second input transistors can form a regulating loop. The regulating loop can regulate the current through the regulating transistor to adjust the bandgap reference voltage at the bandgap voltage node. The regulating loop can adjust the bandgap reference voltage to the sum of the PTAT voltage and the diode voltage.

[0022] In one or more embodiments, the bandgap reference circuit may include an output circuit connected between the bandgap voltage node and a reference node, wherein the output circuit is configured to provide a constant current through the output circuit from the bandgap voltage node to the reference node.

[0023] In one or more embodiments, the output circuit may include an output resistor circuit.

[0024] The output resistor circuit may include multiple resistors.

[0025] In one or more embodiments, the output circuit may include a current sink.

[0026] In one or more embodiments, the current mirror output transistor may be configured to draw a constant current through the regulating transistor, the constant current through the regulating transistor being equal to the constant current provided through the output circuit.

[0027] The current mirror output transistor is configured to mirror a multiple of the PTAT current from the PTAT voltage circuit to provide the constant current through the regulating transistor.

[0028] In one or more embodiments, the bandgap reference circuit may include an output current reference transistor configured to mirror the constant current from the regulating transistor to a constant current output.

[0029] In one or more embodiments, the bandgap reference circuit may include a balancing current transistor, wherein:

[0030] The source terminal of the balancing current transistor is connected to the power supply voltage node; and

[0031] The drain terminal of the balancing current transistor is connected to the bandgap voltage node.

[0032] The balancing current transistor can mirror the PTAT current from the PTAT voltage circuit. The gate of the balancing current transistor can be coupled to the PTAT voltage circuit.

[0033] In one or more embodiments:

[0034] The input circuit can be configured to mirror a first PTAT current from the PTAT voltage circuit;

[0035] The balancing current transistor is configured to mirror a second PTAT current from the PTAT voltage circuit; and

[0036] The current mirror output transistor is configured to mirror a third PTAT current from the PTAT voltage circuit, the third PTAT current being equal to the sum of the first PTAT current and the second PTAT current.

[0037] In one or more embodiments, the first PTAT current may be equal to the second PTAT current.

[0038] The balancing current transistor can mirror the second PTAT current by mirroring the first PTAT current from the input circuit.

[0039] In one or more embodiments, the PTAT voltage circuit may include:

[0040] A PTAT core, comprising a first resistor and configured to generate a PTAT current through the first resistor; and

[0041] An intermediate current mirror branch includes a second resistor and is configured to mirror the PTAT current from the PTAT core through the second resistor to generate the PTAT voltage.

[0042] In one or more embodiments, the resistance of the second resistor may be greater than the resistance of the first resistor.

[0043] According to a second aspect of this disclosure, an automotive transceiver is provided, which includes a bandgap reference circuit as described in any of the preceding technical solutions.

[0044] While this disclosure allows for various modifications and alternatives, their particularities have been illustrated by way of example in the drawings and will be described in detail. However, it should be understood that other embodiments besides the specific embodiments described may also be possible. All modifications, equivalents, and alternative embodiments falling within the spirit and scope of the appended claims are also covered.

[0045] The above discussion is not intended to represent every example embodiment or implementation within the scope of the current or future set of technical solutions. The drawings and the following detailed description also illustrate various example embodiments. A more complete understanding of the various example embodiments can be achieved by considering the following detailed description in conjunction with the accompanying drawings. Attached Figure Description

[0046] One or more embodiments will now be described with reference to the accompanying drawings, by way of example only, in which:

[0047] Figure 1 An example embodiment of a bandgap reference circuit according to an embodiment of the present disclosure is shown;

[0048] Figure 2A The temperature variation of a bandgap reference circuit according to an embodiment of the present disclosure is shown;

[0049] Figure 2B Further temperature dependence of the bandgap reference circuit according to embodiments of the present disclosure is shown;

[0050] Figure 2C The noise performance of a bandgap reference circuit according to an embodiment of the present disclosure is shown;

[0051] Figure 2D The simulated fabrication variability of the bandgap reference voltage of the bandgap reference circuit according to an embodiment of the present disclosure is shown;

[0052] Figure 2E The simulated fabrication variability of the quiescent current of a bandgap reference circuit according to an embodiment of the present disclosure is shown.

[0053] Figure 2F The power supply voltage EMI tolerance of a bandgap reference circuit according to an embodiment of the present disclosure is shown;

[0054] Figure 2G The diagram illustrates the handling of wafer EMI tolerances for a bandgap reference circuit according to embodiments of the present disclosure; and

[0055] Figure 2H The ground node EMI tolerance of a bandgap reference circuit according to an embodiment of the present disclosure is shown. Detailed Implementation

[0056] This disclosure provides a bandgap reference circuit that achieves a smaller area and lower current consumption compared to the PN diode Banba architecture, while maintaining the same or improved accuracy and noise performance. The problem with reducing current consumption and area in Banba circuits is that these two factors are contradictory. Reducing current consumption leads to a larger resistor. Reducing the resistor size leads to a less accurate reference voltage.

[0057] The invention described herein designs a novel bandgap reference architecture that uses a smaller area and produces lower noise compared to the Banba architecture.

[0058] Figure 1 A bandgap reference circuit 100 according to an embodiment of the present disclosure is shown. The bandgap reference circuit 100 includes a temperature-to-absolute-temperature (PTAT) voltage circuit 102 and a bandgap voltage circuit 104. The bandgap reference circuit 104 includes a diode 114. The bandgap reference circuit 104 is configured to receive a PTAT voltage Vptat from the PTAT voltage circuit 102 and combine (e.g., sum) the PTAT voltage Vptat with the diode voltage across the diode 114 to generate a bandgap reference voltage VBG.

[0059] Because the diode voltage is complementary to the absolute temperature (CTAT), the resulting bandgap reference voltage VBG advantageously provides a fixed, essentially temperature-independent voltage reference. The addition of the PTAT and CTAT components produces a temperature-independent voltage with typical bandgap curvature.

[0060] In this example, the PTAT voltage circuit 102 is configured to generate a PTAT voltage Vptat from a supply voltage VIO received at supply voltage node 106. The PTAT voltage circuit 102 may include a PTAT core 108, which is configured to generate a PTAT current Iptat. The PTAT voltage circuit 102 may include an intermediate branch to mirror the PTAT current Iptat from the PTAT core 108 and generate a PTAT voltage Vptat for supply to the bandgap voltage circuit 104. The example PTAT voltage circuit 102 is described in more detail below.

[0061] In this example, the bandgap voltage circuit 104 includes a tail voltage node Vtail 110. Tail voltage node 110 can be configured to receive the PTAT voltage Vptat from the PTAT voltage circuit 102. The bandgap voltage circuit 104 also includes a bandgap voltage node 112, which is configured to output a bandgap reference voltage VBG. The anode of diode 114 is connected to bandgap voltage node 112, and the cathode of diode 114 is connected to tail voltage node 110.

[0062] In this example, the bandgap voltage circuit 104 includes a regulating transistor 115 (labeled MP in the figure), whose source node is coupled to the supply voltage node 106 and whose drain node is coupled to the bandgap voltage node 112. In this example, the regulating transistor 115 is a PMOS transistor. The bandgap voltage circuit 104 also includes a current mirror output transistor 116, whose conductive channel is connected between the tail voltage node 110 and the reference voltage node 118 (which may also be referred to as the ground voltage node). The reference voltage node 118 may be coupled to a reference voltage, such as ground. In this example, the current mirror output transistor 116 is an NMOS transistor.

[0063] The bandgap voltage circuit 104 also includes an input circuit configured to set the tail voltage node to the PTAT voltage Vptat. In this example, the input circuit includes a first input transistor 120 and a second input transistor 122. The source terminal of the first input transistor 120 is connected to the power supply voltage node 106, and the drain terminal of the first input transistor is connected to the gate terminal of the regulating transistor 115. In this example, the first input transistor 120 includes a PMOS transistor. The drain terminal of the second input transistor 122 is connected to the gate terminal of the regulating transistor 115, and the source terminal of the second input transistor 122 is connected to the tail voltage node 110. The input circuit including the first input transistor 120 and the second input transistor 122 forms the output of a current mirror. The gate terminal of each of the first input transistor 120 and the second input transistor 122 is connected to a corresponding terminal of the PTAT voltage circuit 102. The current mirror can mirror the PTAT current Iptat from the PTAT voltage circuit 102 through the conductive channels of the first input transistor 120 and the second input transistor 122, thereby mirroring the PTAT voltage Vptat to the tail voltage node 110.

[0064] A regulation loop is formed by regulating transistor 115, diode 114, first input transistor 120, and second input transistor 122. The regulation loop regulates the bandgap reference voltage VBG at bandgap voltage node 112 by regulating the current of transistor 115 to the sum of the PTAT voltage Vptat and the diode voltage. The regulation loop is similar to a flip-flop voltage follower (FVF) loop and includes a low-dropout (LDO) regulator structure that sums the PTAT voltage Vptat and the diode voltage in one stage. The regulation loop has high loop gain, ensuring good regulation across line and load variations—the bandgap reference voltage VBG is independent of power supply or load changes.

[0065] The bandgap voltage circuit may include an output circuit connected between bandgap voltage node 112 and reference node 118. In this example, the output circuit includes an output resistor circuit 124 connected between bandgap voltage node 112 and reference node 118. In this example, the output resistor circuit includes multiple output resistors, labeled R3, R4, and R5 in the figure. In this way, depending on the relative resistance values ​​of the output resistors, each node between each pair of output resistors can provide an intermediate reference voltage less than the bandgap reference voltage VBG. In this example, the bandgap reference voltage VBG is 1.2 V, and the three output resistors provide additional temperature-independent intermediate reference voltages of 1 V and 0.5 V.

[0066] Since the bandgap reference voltage VBG has a fixed or constant value, connecting the output resistor circuit 124 between the bandgap voltage node 112 and the reference node 118 will generate a constant current Isst flowing through the output resistor circuit during operation. The constant current Isst will be equal to the bandgap reference voltage VBG divided by the resistance of the output resistor circuit 124 (VBG / (R3+R4+R5)). Therefore, the intermediate voltage will be fixed and independent of temperature.

[0067] In other examples, the output circuit may include a current sink instead of the output resistor circuit 124. The current sink can provide a constant current flowing through the output circuit from the bandgap voltage node 112 to the reference node.

[0068] As discussed below, the size of the current mirror output transistor 116 can be set such that it is configured to draw a constant current through the regulating transistor, the constant current through the regulating transistor being equal to the constant current provided through the output circuit.

[0069] In this example, the bandgap voltage circuit 104 includes a balancing current transistor 126. The source terminal of the balancing current transistor 126 is connected to the power supply voltage node, and the drain terminal of the balancing current transistor 126 is connected to the bandgap voltage node 112. The gate of the balancing current transistor 126 is coupled to the PTAT voltage circuit 102 to mirror the PTAT current Iptat. In this example, the gate of the balancing current transistor 126 is connected to the gate of the first input transistor 120 to mirror the PTAT current Iptat. In this example, the balancing current transistor 126 is a PMOS transistor.

[0070] As noted above, the size of the current mirror output transistor is configured such that the current through the regulating transistor 115 matches the current through the output circuit. In some examples, the current mirror output transistor 116 may be configured to mirror a multiple of the PTAT current Iptat from the PTAT voltage circuit 102. The size of the current mirror output transistor is configured to mirror a multiple of the PTAT current Iptat, which is equal to the sum of: (i) the PTAT current Iptat configured to flow through the input circuits (first input transistor 120 and second input transistor 122); and (ii) the PTAT current Iptat configured to flow through the balancing current transistor 126. In other words: the input circuit is configured to mirror the first PTAT current Iptat from the PTAT voltage circuit 102; the balancing current transistor 126 is configured to mirror the second PTAT current Iptat from the PTAT voltage circuit 102; and the current mirror output transistor 116 is configured to mirror the third PTAT current 2*Iptat from the PTAT voltage circuit 102, wherein the third PTAT current 2*Iptat is equal to the sum of the first PTAT current Iptat and the second PTAT current Iptat.

[0071] In this example, the current mirror output transistor 116 is configured to mirror twice the PTAT current 2*Iptat from the PTAT voltage circuit 102. This twice-sized PTAT current 2*Iptat corresponds to the sum of Iptat configured to flow through the first input transistor 120 and the second input transistor 122, and Iptat configured to flow through the balancing current transistor. In other words, the first PTAT current equals the second PTAT current. According to Kirchhoff's current law (the sum of currents entering and exiting a node is equal): (i) the PTAT current Iptat will flow through diode 114; and (ii) the regulating loop will adjust the current through regulating transistor 115 to equal the constant current Isst. Each of these values ​​is taken in turn:

[0072] The PTAT current Iptat supplied through the diode will generate the CTAT diode voltage, which is better complementary to the PTAT voltage Vptat and provides a more constant bandgap reference voltage VBG. This is because the diode voltage's dependence on temperature is non-linear (see [link to relevant documentation]). Figure 2B ).

[0073] ii. A constant current output can be provided by mirroring the constant current Isst of the regulating transistor 115. In this example, the bandgap voltage circuit 104 includes an output current reference transistor 128, which is configured to mirror the flow of the constant current Isst of the regulating transistor 115. In this example, the constant current Isst is 125 nA. In this way, the bandgap reference circuit 100 has the advantageous ability to output any of the following:

[0074] a. Constant voltage – bandgap reference voltage VBG;

[0075] b. Constant current Iconst;

[0076] c. PTAT current Iptat;

[0077] d. PTAT voltage Vptat; and

[0078] e.CTAT current.

[0079] The bandgap reference circuit 100 may include a simple current mirror subtraction circuit (not shown) to output the CTAT current (Iconst-Iptat).

[0080] Some example bandgap voltage circuits 104 may not include the current balancing transistor 126. Therefore: (i) the current mirror output transistor 116 will mirror the (one) times PTAT current Iptat from the PTAT voltage circuit 102; and (ii) the current through the diode will be zero. Such a circuit will still provide a temperature-independent bandgap reference voltage VBG, a constant current through the resistor circuit 124, and a constant current through the regulating transistor 115. However, the temperature independence of the constant current Isst and the bandgap reference voltage VBG may not be as ideal as in examples including the current balancing transistor 126.

[0081] In some examples, the bandgap voltage circuit may include a current sink instead of a resistor circuit 124. The current sink approach may be particularly useful for some applications, such as when a bandgap reference circuit is provided to a digital-to-analog converter (DAC).

[0082] In this example, the bandgap voltage circuit 104 includes a first capacitor C1 connected between the power supply node 106 and the gate terminal of the regulating transistor 115. The first capacitor improves the stability of the regulating loop.

[0083] In this example, the bandgap voltage circuit 104 includes a second capacitor C2 connected in parallel with the current mirror output transistor 116 and a third capacitor C3 connected in parallel with the output resistor circuit 124. The second and third capacitors improve noise / EMI performance.

[0084] Turning to the PTAT voltage circuit 102, in this example, the PTAT voltage circuit 102 includes a PTAT core 108 and an intermediate current mirror branch 109.

[0085] The PTAT core 108 uses a first resistor 149 with resistor R1 to generate the PTAT current Iptat. The PTAT core circuit is well known, and for completeness, a brief description of the operation of the PTAT core circuit is included here.

[0086] The PTAT core 108 includes a current mirror comprising: a first PTAT core transistor 150; a second PTAT core transistor 152; a third PTAT core transistor 154; and a fourth PTAT core transistor 156. The first to fourth PTAT core transistors are arranged in a conventional current mirror configuration. In this example, the first and third PTAT core transistors 150 and 154 are PMOS transistors, and the second and fourth PTAT core transistors 152 and 156 are NMOS transistors. The gates of the first and third PTAT core transistors 150 and 154 are connected together. The gates of the second and fourth PTAT core transistors 152 and 156 are connected together. The gate of the second PTAT core transistor 152 is connected to its drain. The gate of the third PTAT core transistor 154 is connected to its drain.

[0087] The first PTAT core transistor 150 has a source terminal coupled to the power supply voltage node 106 and a drain terminal coupled to the drain terminal of the second PTAT core transistor 152. The source terminal of the second PTAT core transistor 152 is connected to the anode of the first PTAT core diode 158. The cathode of the first PTAT core diode 158 is coupled to the reference node 118.

[0088] The third PTAT core transistor 154 has a source terminal coupled to the power supply voltage node 106 and a drain terminal coupled to the drain terminal of the fourth PTAT core transistor 156. The source terminal of the fourth PTAT core transistor 152 is connected to the first terminal of the first resistor 149. The second terminal of the first resistor 149 is connected to the anode of the second PTAT core diode 160. The cathode of the second PTAT core diode 160 is coupled to the reference node 118. The second PTAT core diode 160 is N times larger than the first PTAT core diode 158.

[0089] The first PTAT core transistor 150, the second PTAT core transistor 152, and the first PTAT core diode 158 define a first branch of the PTAT core 108. The second PTAT core transistor 154, the fourth PTAT core transistor 156, the first resistor 149, and the second PTAT core diode 160 define a second branch of the PTAT core 108.

[0090] Each of the core transistors in the first PTAT core transistor 150, the second PTAT core transistor 152, the third PTAT core transistor 154, and the fourth PTAT core transistor 156 is the same size, such that the current mirror produces the same PTAT current Iptat in each branch. The same voltage is also provided at the source terminals of the second PTAT core transistor 152 and the fourth PTAT core transistor 156.

[0091] More specifically, the voltage Vbe1 across the first PTAT core diode 158 can be written as:

[0092]

[0093] Where V T It is thermal voltage, and I s It is the saturation current.

[0094] The voltage Vbe2 across the second PTAT core diode 160 can be written as:

[0095]

[0096] The difference between Vbe1 and Vbe2 provides the voltage across the first transistor 149:

[0097]

[0098] Where K is the Boltzmann constant and q is the electron charge. The voltage drop across the first resistor 149 is proportional to the temperature, which generates the PTAT current Iptat in the PTAT core 108.

[0099] The intermediate current mirror branch 109 mirrors the PTAT current Iptat from the PTAT core 108 through a second resistor 162 with resistance R2, to generate a PTAT voltage Vptat. The magnitude of the PTAT voltage Vptat depends on the ratio of the resistance R2 of the second resistor 162 to the resistance R1 of the first resistor 149. The PTAT voltage Vptat can be written as:

[0100]

[0101] In some cases, resistor R2 is greater than resistor R1, causing the PTAT voltage Vptat to be greater than the PTAT voltage across the first resistor 149.

[0102] The intermediate current mirror branch 109 and the input circuit of the bandgap voltage circuit 104 can form a current mirror. The intermediate current mirror branch 109 and the input circuit can mirror the PTAT current Iptat to the input circuit, thereby setting the tail voltage node 110 to the PTAT voltage Vptat.

[0103] In this example, the intermediate current mirror branch 109 includes a first intermediate transistor 164, a second intermediate transistor 166, and a second resistor 162. The first intermediate transistor 164 is a PMOS transistor, and the second intermediate transistor 166 is an NMOS transistor. The source terminal of the first intermediate transistor 164 is connected to the power supply voltage node 106, and the drain terminal of the first intermediate transistor 164 is coupled to the drain terminal of the second intermediate transistor 166. The source terminal of the second intermediate transistor 166 is connected to a first terminal of the second resistor 162, and the second terminal of the second resistor 162 is connected to a reference node 118. The gate terminal of the first intermediate transistor 164 is connected to the gate terminal of a third PTAT core transistor 154. The gate terminal of the first intermediate transistor 164 is also connected to the gate terminal of a first input transistor 120. The gate terminal of the second intermediate transistor is connected to the gate terminal of a second input transistor 122 and to the drain terminal of the second intermediate transistor 166.

[0104] In this example, the PTAT voltage circuit 102 includes an additional current mirror branch 168. This additional current mirror branch 168 is configured to mirror the PTAT current Iptat to the current mirror output transistor 116 of the bandgap voltage circuit 104. As noted above, the current mirror output transistor 116 can be scaled such that it mirrors the PTAT current Iptat by a multiple, in this example, 2 * Iptat.

[0105] The additional current mirror branch 168 includes a first additional transistor 170 and a second additional transistor 172. In this example, the first additional transistor 170 is a PMOS transistor, and the second additional transistor 172 is an NMOS transistor. The source terminal of the first additional transistor 170 is connected to the power supply voltage node 106, and the drain terminal of the first additional transistor 170 is connected to the drain terminal of the second additional transistor 172. The source terminal of the second additional transistor 172 is connected to the reference node 118. The gate terminal of the second additional transistor 172 is connected to the drain terminal of the second additional transistor 172 and the gate terminal of the current mirror output transistor 116. The gate terminal of the first additional transistor 170 is connected to the gate terminal of the first PTAT core transistor 150.

[0106] exist Figure 1 In this example, the gate terminals of each of the following transistors are connected together: the first PTAT core transistor 150, the third PTAT core transistor 154, the first intermediate transistor 164, the first additional transistor 170, the first input transistor 120, and the current balancing transistor 126. In this way, the PTAT current Iptat is configured to flow through each corresponding branch of the bandgap reference circuit 100.

[0107] In a bandgap reference circuit, the bandgap reference voltage VBG can be fine-tuned by changing the resistance ratio R2 / R1. Fine-tuning of the intermediate reference voltage can also be achieved by adjusting the value of the output resistor.

[0108] In some examples, all transistors in the bandgap reference circuit may have the same turn-on voltage. For example, all transistors may have the same gate-source voltage. In some examples, all transistors may have a gate-source voltage of 1.5 V or 1.3 V. In this way, the bandgap reference circuit can operate at voltages as low as 1.5 V or 1.3 V.

[0109] In summary, the bandgap reference circuit includes:

[0110] 1. A PTAT core 108 for generating a PTAT current Iptat, which is mirrored to a second resistor 162 to generate a PTAT voltage Vptat.

[0111] 2. The PTAT voltage Vptat is mirrored into the bandgap voltage circuit 104 and a diode voltage is applied to generate the bandgap reference voltage VBG.

[0112] 3. The bandgap reference circuit 100 can output separate PTAT and CTAT currents for use in other circuits.

[0113] 4. As discussed below, this unique solution consumes less current and occupies less area than the Banba configuration, and produces lower overall noise.

[0114] Figures 2A to 2H The analog performance of a bandgap reference circuit according to an embodiment of the present disclosure is shown.

[0115] Figure 2A This includes a first curve 230 showing the bandgap reference voltage as a function of temperature, and a second curve 232 showing the intermediate reference voltage at 1 V as a function of temperature. Typical bandgap performance can be observed.

[0116] Figure 2BThe same curve 230 shows the bandgap reference voltage as a function of temperature, as well as a second curve 234 showing the PTAT voltage Vptat as a function of temperature and a third curve 236 showing the CTAT diode voltage Vbe as a function of temperature. The bandgap reference voltage is equal to the sum of the PTAT voltage Vptat and the CTAT diode voltage Vbe.

[0117] Figure 2C The noise performance of the bandgap reference circuit is shown. First curve 238 shows the frequency-varying noise performance for a typical Banba architecture. Second curve 240 shows the frequency-varying noise performance of the bandgap reference circuit according to an embodiment of this disclosure. Noise is higher at low frequencies due to flicker noise. However, the flicker noise of the bandgap reference circuit of this disclosure is reduced by ~20%. This is because, unlike the Banba architecture, the bandgap reference circuit of this disclosure does not include an operational transconductance amplifier (OTA). Although not visible in the curves, the noise performance of the bandgap reference circuit is also better than that of the Banba architecture at high frequencies, and the total integrated noise is significantly reduced by a factor of 5 between 100 MHz and 1 MHz.

[0118] Figure 2D Monte Carlo simulations are shown to illustrate the distribution of the bandgap reference voltage at three different temperatures (-40°C, 25°C, and 175°C) for simulating typical manufacturing variations of the bandgap reference circuit according to this disclosure. The voltage diffusion (stdev of ~11mV) is performance-similar to the Banba architecture. The bandgap reference circuit according to this disclosure has an area reduction of approximately 20% compared to a typical Banba bandgap circuit. This is due to the smaller total rpoly resistor area. Figure 2D This demonstrates that a smaller area does not lead to performance degradation compared to the Banba architecture.

[0119] Figure 2E Monte Carlo simulations are shown to illustrate the distribution of quiescent current Iq at three different temperatures (-40°C, 25°C, and 175°C) for simulating typical manufacturing variations of the bandgap reference circuit according to this disclosure. The central plot shows a quiescent current consumption of 730 nA, which is more than twice the typical Banba current consumption of 1.6–1.7 uA.

[0120] A common problem in automotive CAN / 10BaseT1s transceiver systems is that the bandgap reference circuit must be low-current, small-area, and EMI resistant. Figures 2F to 2H The bandgap reference circuit is shown to perform well in EMI simulation.

[0121] Figure 2FThe tolerance of the bandgap reference circuit to EMI noise at the supply voltage node is shown. Each plot shows the maximum EMI tolerance at different frequency values ​​of EMI noise. The peak-to-peak tolerance is twice the value shown. At high frequencies, the peak-to-peak EMI tolerance at the supply voltage node is higher than 2 V.

[0122] Figure 2G The tolerance of the bandgap reference circuit to EMI noise at the chip is shown. Each plot shows the maximum EMI tolerance at different frequency values ​​of EMI noise. The peak-to-peak EMI tolerance is ~3.6 V at all test frequencies.

[0123] Figure 2H The diagram shows the tolerance of the bandgap reference circuit to EMI noise at the reference node. Each plot shows the maximum EMI tolerance across a range of different EMI noise frequency values. At high frequencies, the peak-to-peak EMI tolerance at the reference voltage node is greater than 2V.

[0124] Figures 2F to 2H The EMI / electromagnetic compatibility (EMC) behavior is shown to be similar to that of a conventional bandgap reference circuit.

[0125] The disclosed bandgap reference circuit 100 offers several advantages over conventional Banba architectures:

[0126] 1. The ability to generate constant voltage, constant current, PTAT voltage, PTAT current, and CTAT current. Banba only provides constant voltage and current.

[0127] 2. No OTA updates, thus reducing flicker noise.

[0128] 3. More generally, lower noise performance ( Figure 2C ).

[0129] 4. Lower current consumption ( Figure 2E ).

[0130] 5. Lower turn-on voltage (1.3 V).

[0131] 6. Smaller area (smaller resistor).

[0132] 7. No buffer circuit is required for the bandgap reference voltage VBG. Conventional bandgap reference circuits typically require a buffer circuit on the output of the bandgap reference circuit to prevent the load from affecting the bandgap reference voltage. The regulation loop of the example bandgap reference circuit can act as a buffer, thus eliminating the need for a buffer circuit on the output.

[0133] While achieving the above advantages, the disclosed bandgap reference circuit provides EMI tolerance similar to that of a conventional Banba design and sigma performance (VBG accuracy) similar to Banba performance.

[0134] The disclosed bandgap reference circuit provides a low-power, low-voltage, EMI-resistant bandgap reference circuit that can generate constant voltage and current.

[0135] This disclosure provides an EMC-resistant bandgap reference circuit suitable for systems where the bandgap reference needs to be ready at low voltage supply values ​​and generate a constant reference voltage and current while consuming low current.

[0136] The disclosed bandgap reference circuit can be particularly advantageous in automotive transceivers, for example, in low-power backbones of automotive transceivers such as 10 BASE-T1S and CAN XL.

[0137] Unless a specific order is explicitly stated, the instructions and / or flowchart steps in the above diagrams may be performed in any order. Furthermore, those skilled in the art will recognize that while an example set of instructions / methods has been discussed, the material in this specification can be combined in various ways to produce other examples, and should be understood within the context provided in the detailed description herein.

[0138] In some example embodiments, the instruction set / method steps described above are implemented as functional and software instructions embodied in an executable instruction set, which is implemented on a computer or machine programmed and controlled with said executable instructions. Such instructions are loaded to execute on a processor (e.g., one or more CPUs). The term processor includes a microprocessor, microcontroller, processor module or subsystem (including one or more microprocessors or microcontrollers), or other control or computing device. A processor may refer to a single component or multiple components.

[0139] In other examples, the instruction sets / methods illustrated herein, along with their associated data and instructions, are stored in appropriate storage devices, which are implemented as one or more non-transitory machine- or computer-readable or computer-usable storage media. Such computer-readable or computer-usable storage media are considered part of an article (or article of manufacture). An article or article of manufacture may refer to any single or multiple components manufactured. Non-transitory machine- or computer-usable media as defined herein do not include signals, but such media may be capable of receiving and processing information from signals and / or other transient media.

[0140] Example embodiments of the materials discussed in this specification may be implemented, in whole or in part, via networks, computers, or data-based devices and / or services. These may include cloud, internet, intranet, mobile devices, desktop computers, processors, lookup tables, microcontrollers, consumer devices, infrastructure, or other enabling devices and services. As may be used herein and in the claims, the following non-exclusive definitions are provided.

[0141] In one example, one or more instructions or steps discussed in this article are automated. The terms automation or automaticity (and similar variations) mean the use of computers and / or mechanical / electrical devices to control the operation of equipment, systems, and / or processes without human intervention, observation, effort, and / or decision-making.

[0142] It should be understood that any components that are alleged to be coupled may be directly or indirectly coupled or connected. In the case of indirect coupling, an additional component may be placed between the two components that are alleged to be coupled.

[0143] In this specification, exemplary embodiments have been presented based on a selected set of details. However, those skilled in the art will understand that many other exemplary embodiments, including different selected sets of details, can be practiced. It is intended that the appended claims cover all possible exemplary embodiments.

Claims

1. A bandgap reference circuit, characterized in that, include: A PTAT voltage circuit proportional to absolute temperature, configured to generate a PTAT voltage; as well as A bandgap voltage circuit, comprising a diode, is configured to: Receive the PTAT voltage from the PTAT voltage circuit; as well as The PTAT voltage is combined with the diode voltage across the diode to output a bandgap reference voltage.

2. The bandgap reference circuit according to claim 1, characterized in that, The bandgap voltage circuit includes: A bandgap voltage node configured to output the bandgap reference voltage; and The tail voltage node is configured to be set to the PTAT voltage. The anode of the diode is connected to the bandgap voltage node, and the cathode of the diode is connected to the tail voltage node.

3. The bandgap reference circuit according to claim 2, characterized in that, The bandgap voltage circuit includes: A regulating transistor having a source terminal coupled to a power supply voltage node and a drain terminal connected to the bandgap voltage node; An input circuit, coupled to the PTAT voltage circuit, and configured to set the tail voltage node to the PTAT voltage; and The current mirror output transistor has a conductive channel connected between the tail voltage node and the reference voltage node.

4. The bandgap reference circuit according to claim 3, characterized in that, The input circuit includes: A first input transistor, wherein the source terminal of the first input transistor is connected to the power supply node, and the drain terminal of the first input transistor is connected to the gate terminal of the regulating transistor; and A second input transistor, wherein the drain terminal of the second input transistor is connected to the gate terminal of the regulating transistor, and the source terminal of the second input transistor is connected to the tail voltage node.

5. The bandgap reference circuit according to any one of claims 2 to 4, characterized in that, The bandgap reference circuit includes an output circuit connected between the bandgap voltage node and a reference node, wherein the output circuit is configured to provide a constant current from the bandgap voltage node to the reference node through the output circuit.

6. The bandgap reference circuit according to claim 5, characterized in that, The output circuit includes an output resistor circuit.

7. The bandgap reference circuit according to claim 5, characterized in that, The output circuit includes a current sink.

8. The bandgap reference circuit according to any one of claims 5 to 7, when subordinate to claim 3 or 4, is characterized in that, The current mirror output transistor is configured to draw a constant current through the regulating transistor, the constant current through the regulating transistor being equal to the constant current provided through the output circuit.

9. The bandgap reference circuit according to claim 8, characterized in that, The bandgap reference circuit includes an output current reference transistor configured to mirror the constant current from the regulating transistor to a constant current output.

10. An automotive transceiver, characterized in that, Includes the bandgap reference circuit as described in any of the preceding claims.

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