Bias current generating circuit

Abstract

The utility model relates to the technical field of electronic circuits, and discloses a bias current generating circuit, which comprises a signal conversion unit configured to receive an external first signal and convert the external first signal into a set second signal; the reference voltage generation unit is configured to receive and respond to the set second signal to output a reference voltage signal; the PTAT voltage generation unit comprises a PTAT current source and a divider resistor subunit which are connected in series, and one end of the divider resistor subunit outputs a PTAT voltage signal; the bias current output unit comprises a first bias current output path and a second bias current output path; the input end of the signal output unit is used for receiving the reference voltage signal and the PTAT voltage signal; and the output end of the signal output unit is used for outputting a bias current selection signal and gating the first bias current output path or the second bias current output path. The operational amplifier bias module has the effect of reducing the influence of the temperature on the operational amplifier bias module.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic circuit, in particular to a bias current generating circuit. BACKGROUND

[0002] In analog integrated circuits, the operational amplifier is the most common basic module, and various functional modules such as amplification and filtering can be realized by using the operational amplifier.

[0003] In related technologies, the operational amplifier bias module is generally biased by using a constant current source, but the characteristics of MOS tubes, resistors and capacitors in the operational amplifier fluctuate due to temperature, resulting in a large difference between the performance of the operational amplifier at high and low temperatures and the performance at normal temperature, and there is room for improvement. SUMMARY

[0004] In order to reduce the influence of temperature on the operational amplifier bias module, the present application provides a bias current generating circuit.

[0005] The present application provides a bias current generating circuit, which adopts the following technical scheme:

[0006] A bias current generating circuit comprises:

[0007] A signal conversion unit is configured to receive an external first signal and convert it into a set second signal;

[0008] A reference voltage generating unit is configured to receive and respond to the set second signal to output a reference voltage signal;

[0009] A PTAT voltage generating unit comprises a PTAT current source and a voltage dividing resistor subunit connected in series, and one end of the voltage dividing resistor subunit outputs a PTAT voltage signal;

[0010] A bias current output unit comprises a first bias current output path and a second bias current output path;

[0011] A signal output unit has an input end for receiving the reference voltage signal and the PTAT voltage signal, and an output end for outputting a bias current selection signal and selecting the first bias current output path or the second bias current output path.

[0012] By adopting the above technical scheme, the PTAT current source outputs a PTAT current to bias the circuit, so that the bias circuit current is relatively small at low temperature and relatively large at high temperature compared with normal temperature, and by processing the reference voltage signal and the PTAT voltage signal, the output bias current selection signal for selecting the first bias current output path or the second bias current output path is outputted, thereby improving the fluctuation of the performance of the operational amplifier at high and low temperatures.

[0013] Optionally, the signal conversion unit comprises a decoder, which converts the first signal into the set second signal.

[0014] By using the above technical solution, the first signal is converted into the second signal based on the use of the decoder, efficient conversion of the signal is realized, and the stability and accuracy of signal conversion are improved.

[0015] Optionally, the reference voltage generation unit comprises a first control switch and a second control switch controlled by the set second signal, a reference voltage VDD, a first current source and a plurality of series-connected resistance strings connected in series.

[0016] The input end of the first control switch is connected between the output end of the first current source and the input end of the resistance string, the input end of the second control switch is connected between two adjacent resistors in the resistance string, and the output end of the first control switch is connected with the output end of the second control switch and then connected with the signal output unit.

[0017] Optionally, the PTAT voltage generation unit comprises a first power supply voltage VDD, a first resistor Ra and a second resistor Rb connected in series, and one end of the second resistor Rb away from the first resistor Ra is grounded.

[0018] Optionally, the signal output unit comprises a comparator, the first input end of the comparator is connected with the output end of the first control switch and the output end of the second control switch, and the second input end of the comparator is connected between the first resistor Ra and the second resistor Rb.

[0019] Optionally, the signal output unit further comprises an inverter, the input end of the inverter is connected with the output end of the comparator.

[0020] Optionally, the first bias current output path comprises a second power supply voltage VDD, a third current source and a third control switch connected in series.

[0021] Optionally, the second bias current output path comprises a third power supply voltage VDD, a fourth current source and a fourth control switch connected in series.

[0022] In summary, the present application has at least one of the following beneficial technical effects: the PTAT current source outputs a PTAT current to bias the circuit, so that the bias circuit current is relatively small at low temperature and relatively large at high temperature compared with normal temperature, and by processing the reference voltage signal and the PTAT voltage signal, an output bias current selection signal for selecting the first bias current output path or the second bias current output path is output, thereby improving the performance fluctuation of the operation at high and low temperatures. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a block diagram of a bias current generation circuit.

[0024] Figure 2 is a circuit diagram of a bias current generation circuit.

[0025] Reference signs: 1, signal conversion unit; 2, reference voltage generation unit; 3, PTAT voltage generation unit; 4, bias current output unit; 5, signal output unit. DETAILED DESCRIPTION

[0026] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. Figures 1-2 The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings.

[0027] In the description of the present application, the description of the terms "certain embodiments", "one embodiment", "some embodiments", "illustrative embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in connection with the embodiments or examples are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0028] The embodiments of the present application disclose a bias current generation circuit, referring to Figure 1 , comprising a signal conversion unit 1, a reference voltage generation unit 2, a PTAT voltage generation unit 3, a bias current output unit 4 and a signal output unit 5. The signal conversion unit 1 is configured to receive an external first signal and convert it into a set second signal.

[0029] Specifically, referring to Figure 2 , the signal conversion unit 1 comprises a decoder, and the input end of the decoder is connected to the first signal. In the embodiments of the present application, the first signal is an analog temperature control signal, and the set second signal output after the first signal is processed by the decoder is a digital control signal. Of course, the signal conversion of the decoder includes but is not limited to analog-to-digital conversion, which is not limited here.

[0030] The reference voltage generation unit 2 is configured to receive and respond to the set second signal to output a reference voltage signal. Specifically, the reference voltage generation unit 2 comprises a first control switch S1 and a second control switch controlled by the set second signal, a reference voltage VDD1, a first current source I1 and a plurality of series-connected resistance strings connected in series.

[0031] The input terminal of the first control switch S1 is connected between the output terminal of the first current source I1 and the input terminal of the resistor string. Multiple second control switches are provided; this example uses one second control switch. The input terminal of the second control switch is connected between two adjacent resistors in the resistor string. After the output terminals of the first and second control switches are connected, the aforementioned reference voltage signal is output and connected to the signal output unit 5.

[0032] The first current source I1 is a constant voltage source. The current generated flows through resistors R0-Rn, and a constant voltage V0-Vn proportional to the resistance value is generated on resistors R0-Rn. The second signal is set to control the first control switch S1 and the second control switches S20-S2n to be open at the same time. That is, the output voltage of the reference voltage generation unit 2 is a constant reference voltage that is positively correlated with the switching point temperature.

[0033] Continue to refer to Figure 2 The PTAT voltage generating unit 3 includes a PTAT current source I2 connected in series and a voltage divider unit. One end of the voltage divider unit outputs a PTAT voltage signal, which gradually increases as the temperature increases. The voltage divider unit includes a first supply voltage VDD1, a first resistor Ra, and a second resistor Rb connected in series. The end of the second resistor Rb furthest from the first resistor Ra is grounded. The aforementioned PTAT voltage signal is output between the first resistor Ra and the second resistor Rb.

[0034] Specifically, the input terminal of signal output unit 5 is used to receive a reference voltage signal and a PTAT voltage signal, and the output terminal of signal output unit 5 is used to output a bias current selection signal. Signal output unit 5 includes a comparator and an inverter. The first input terminal of the comparator is connected to the output terminals of the first and second control switches. The second input terminal of the comparator is connected between the first resistor Ra and the second resistor Rb. The input terminal of the inverter is signal-connected to the output terminal of the comparator. The first input terminal of the comparator receives the aforementioned reference voltage signal, and the second input terminal of the comparator receives the aforementioned PTAT voltage signal.

[0035] The bias current selection signal includes the signal bias_en and the signal bias_enb. The comparator compares the magnitude of the PTAT voltage signal and the reference voltage signal. If the reference voltage signal is greater than the PTAT voltage signal, the comparator outputs the signal bias_en. When the set switching temperature point is reached, the reference voltage signal is less than the PTAT voltage signal, and the comparator outputs the signal bias_en, which is then inverted to become the signal bias_enb.

[0036] The bias current output unit 4 comprises a first bias current output path and a second bias current output path, wherein the first bias current output path comprises the second power supply voltage VDD2, the third current source I3 and the third control switch SWb connected in series, and the second bias current output path comprises the third power supply voltage VDD3, the fourth current source I4 and the fourth control switch SWa connected in series.

[0037] The signal bias_en and the signal bias_enb are connected with the control ports of the fourth control switch SWa and the third control switch SWb, respectively. In the bias current generation circuit, the fourth current source I4 is a PTAT current source, the current size of which is proportional to temperature, the fourth current source I4 is connected to one end of the fourth control switch SWa, the third current source I3 is a constant voltage current generated on a high-precision resistor, the third current source I3 is a constant current that does not fluctuate with temperature, the current is connected to one end of the switch SWb, the switch SWa and the switch SWb are controlled by the signal bias_en and the signal bias_enb, respectively, and only one switch is turned on at the same time, when the temperature is less than the set switching temperature point, the signal bias_en controls the switch SWa to be turned on, the signal bias_enb controls the switch SWb to be turned off, and the output end of the bias current output unit 4 flows through the PTAT current; when the temperature is higher than the set switching temperature point, the signal bias_en controls the switch SWa to be turned off, the signal bias_enb controls the switch SWb to be turned on, and the output end of the bias current output unit 4 flows through the constant current signal.

[0038] Although the embodiments of the present application have been shown and described above, it should be understood that the above-described embodiments are exemplary, and should not be construed as limiting the present application, and those of ordinary skill in the art can make changes, modifications, replacements and variations to the above-described embodiments within the scope of the present application.

Claims

1. A bias current generating circuit characterized by comprising: The application relates to a signal conversion unit (1) configured to receive an external first signal and convert the first signal into a second signal; a reference voltage generating unit (2) configured to receive the second signal and output a reference voltage signal in response to the second signal; a PTAT voltage generating unit (3) comprising a PTAT current source and a voltage dividing subunit connected in series, one end of the voltage dividing subunit outputting a PTAT voltage signal; a bias current output unit (4) comprising a first bias current output path and a second bias current output path; and a signal output unit (5) having an input end configured to receive the reference voltage signal and the PTAT voltage signal, and an output end configured to output a bias current selection signal and select the first bias current output path or the second bias current output path. The signal conversion unit (1) comprises a decoder configured to convert the first signal into the second signal. The reference voltage generating unit (2) comprises a first control switch and a second control switch controlled by the second signal, a reference voltage VDD, a first current source and a plurality of resistors connected in series. An input end of the first control switch is connected between an output end of the first current source and an input end of the resistors, an input end of the second control switch is connected between two adjacent resistors in the resistors, and an output end of the first control switch is connected with an output end of the second control switch and then connected with the signal output unit (5). The voltage dividing subunit comprises a first supply voltage VDD, a first resistor Ra and a second resistor Rb connected in series. The signal output unit (5) comprises a comparator having a first input end connected with the output end of the first control switch and the output end of the second control switch, and a second input end connected between the first resistor Ra and the second resistor Rb.

2. The bias current generation circuit according to claim 1, wherein The signal output unit (5) further comprises an inverter having an input end connected with an output end of the comparator.

3. The bias current generation circuit according to claim 1, wherein The first bias current output path comprises a second supply voltage VDD, a third current source and a third control switch connected in series. The second bias current output path comprises a third supply voltage VDD, a fourth current source and a fourth control switch connected in series.

4. The bias current generation circuit according to claim 3, wherein ​ 5. The bias current generation circuit according to claim 4, wherein ​ 6. The bias current generation circuit according to claim 5, wherein ​ 7. The bias current generation circuit according to claim 1, wherein ​ 8. The bias current generation circuit according to claim 1, wherein ​

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