Band-splitting amplifier and its application

Abstract

The present disclosure provides a frequency band separation amplifier, including an input transconductance stage, a bias current source, a filter network, a load stage, and a common mode feedback network. The input transconductance stage is used to convert an input signal into a current signal; the bias current source is used to provide a suitable bias for the input transconductance stage; the filter network is configured to include two different transmission paths, a low-frequency transmission path and an intermediate frequency transmission path, and different transmission zero poles are introduced in different transmission paths, so that the low-frequency transmission path presents a low-pass characteristic, and the intermediate frequency transmission path presents a band-pass characteristic, thereby outputting a low-frequency signal and an intermediate frequency signal; the low-frequency signal and the intermediate frequency signal are obtained after passing through the load stage. The common mode feedback network is used to stabilize the common mode level of the low-frequency output and the intermediate frequency output at the output end. At the same time, the application of the above-mentioned frequency band separation amplifier in a receiver and an IOT communication system involving multiple down-conversion operations is also provided.

Description

Technical Field

[0001] The present disclosure relates to the technical fields of integrated circuits and radio frequency wireless communications, and in particular to a frequency band separation amplifier and its application. Background Art

[0002] The Internet of Things (IoT) collects the required information in real time through various devices such as sensors, and connects everything through various network accesses. With the rapid increase in the number of IoT nodes, it is very necessary to reduce the size and power consumption of IoT communication nodes.

[0003] Wireless communication receivers can effectively improve their anti-interference capabilities by using multiple down-conversion architectures, but the multiple down-conversion mechanism requires the introduction of multiple filters and amplifiers to filter and amplify signals. Although the introduction of off-chip high-Q filters based on micro-electro-mechanical systems (MEMS) resonators does not increase additional power consumption, their large size limits their application in IoT communication nodes; active RC filters, MOSFET-C filters, and gm-C filters are relatively small in size, but their power consumption is relatively high.

[0004] In addition, multiple down-conversion processes will generate a mixed signal containing intermediate frequency components and low frequency components. Sometimes it is necessary to separate the two frequency components in the mixed signal for separate processing by the subsequent circuits. This also requires the introduction of multiple filters, which increases power consumption, cost and system complexity. Summary of the invention

[0005] In view of this, in order to at least partially solve at least one of the above-mentioned technical problems, the present disclosure provides a frequency band separation amplifier and application.

[0006] In order to achieve the above purpose, the technical solution of the present invention is as follows:

[0007] According to an embodiment of one aspect of the present disclosure, a frequency band separation amplifier and application are provided, including an input transconductance stage, a bias current source, a filter network, a load stage, and a common mode feedback network. The input transconductance stage is used to convert an input signal into a current signal; the bias current source is used to provide a suitable bias for the input transconductance stage; the filter network is configured to include two different transmission paths, a low-frequency transmission path and an intermediate frequency transmission path, and different transmission zero poles are introduced in different transmission paths, so that the low-frequency transmission path presents a low-pass characteristic and the intermediate frequency transmission path presents a band-pass characteristic, thereby outputting a low-frequency signal and an intermediate frequency signal; the low-frequency signal and the intermediate frequency signal are obtained after passing through the load stage to obtain a low-frequency output and an intermediate frequency output; the common mode feedback network is used to stabilize the common mode level of the low-frequency output and the intermediate frequency output at the output end.

[0008] According to an embodiment of the present disclosure, the input signal includes multiple frequency components, including at least a low-frequency component and a medium-frequency component.

[0009] According to the embodiment of the present disclosure, the frequency band separation amplifier can be single-ended input and single-ended output; or can be differential input and differential output.

[0010] According to the embodiment of the present disclosure, the input transconductance stage may use an NMOS transistor or a PMOS transistor; the load stage may use a PMOS active load or an NMOS active load.

[0011] According to an embodiment of the present disclosure, the filtering network includes a capacitor network or a combination of a capacitor network and a resistor network.

[0012] According to the embodiments of the present disclosure, the capacitor network may use a programmable capacitor array; the resistor network may use a programmable resistor array, or use polysilicon resistors, or use MOS tubes as pseudo resistors.

[0013] According to an embodiment of the present disclosure, the bias current source uses a current mirror to replicate the current of a reference current source to provide a bias for the amplifier, and NMOS or PMOS may be used to replicate the current.

[0014] According to the embodiment of the present disclosure, the current mirror of the bias current source can use a single MOS tube to provide a certain replica current, or a programmable MOS tube array can be used to achieve adjustable bias current, thereby achieving adjustability of gain and frequency selection.

[0015] According to an embodiment of the present disclosure, the common-mode feedback network adopts a resistor network or uses a high-gain operational amplifier to stabilize the output common-mode level.

[0016] Another aspect of the present disclosure provides an application of the frequency band separation amplifier described in any one of the above items in a receiver and an IOT communication system involving multiple down-conversion operations.

[0017] In a low-power receiver using a multiple down-conversion architecture, if there is an interference signal in the passband, the interference signal itself will also undergo self-mixing and down-conversion to the baseband, resulting in a DC signal power higher than the intermediate frequency signal power. The stronger the interference signal, the greater the ratio of the DC signal to the intermediate frequency signal power. For a signal that contains both intermediate frequency components and low-frequency components in the spectrum, if you want to observe the signal strength of the intermediate frequency and low-frequency components separately, the traditional approach is to input the signal into a low-pass filter and a band-pass filter respectively, and then observe the output signal strength of the two paths respectively. By using the frequency band separation amplifier disclosed in the present invention to process such an input signal, the two transmission paths with different filtering characteristics inside the amplifier are used (the intermediate frequency transmission path presents a band-pass characteristic, and the low-frequency transmission path presents a low-pass characteristic), and the separation of the intermediate frequency signal and the DC signal can be effectively achieved with lower power consumption and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0019] Figure 1 The structure diagram of the frequency band separation amplifier according to the embodiment of the present disclosure is schematically shown;

[0020] Figure 2 A circuit structure diagram of a frequency band separation amplifier according to an embodiment of the present disclosure is schematically shown;

[0021] Figure 3 The circuit structure diagram of another frequency band separation amplifier according to an embodiment of the present disclosure is schematically shown. DETAILED DESCRIPTION

[0022] In order to reduce the use of filters in ultra-low power IoT communication circuits and thereby reduce the volume and power consumption of communication nodes, the present disclosure provides a frequency band separation amplifier and its application. The amplifier can obtain the signal strength of the low-frequency and intermediate-frequency components in the spectrum according to the signal strength of the intermediate-frequency output terminal and the low-frequency output terminal of the frequency band separation amplifier and the gain of the two signal transmission paths, thereby indirectly reflecting the relative strength of the interference signal and the target signal, thereby realizing signal filtering separation with low power consumption and small volume.

[0023] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0024] In an embodiment of the present disclosure, a frequency band separation amplifier is provided, such as Figure 1 As shown, the frequency band separation amplifier includes: an input transconductance stage, a bias current source, a filter network, a load stage, and a common mode feedback network. The input transconductance stage is used to convert the input signal into a current signal; the bias current source is used to provide a suitable bias for the input transconductance stage; the filter network is configured to include two different transmission paths, a low-frequency transmission path and an intermediate frequency transmission path, and different transmission zero poles are introduced in different transmission paths, so that the low-frequency transmission path presents a low-pass characteristic and the intermediate frequency transmission path presents a band-pass characteristic, thereby outputting a low-frequency signal and an intermediate frequency signal; the low-frequency signal and the intermediate frequency signal are obtained after passing through the load stage to obtain a low-frequency output and an intermediate frequency output; the common mode feedback network is used to stabilize the common mode level of the low-frequency output and the intermediate frequency output at the output end.

[0025] like Figure 1As shown, the input signal can be a complex signal containing multiple frequency components (including at least low-frequency components and intermediate-frequency components), for example, an input voltage signal including low-frequency components and intermediate-frequency components, which is converted into a current signal after being input to the input transconductance stage of the frequency band separation amplifier; the filter network introduces different zero poles in the low-frequency transmission path and the intermediate-frequency transmission path, respectively, so that the low-frequency transmission path presents a low-pass characteristic, and the intermediate-frequency transmission path presents a band-pass characteristic, thereby obtaining a low-frequency signal and an intermediate-frequency signal; and then obtaining a low-frequency output and an intermediate-frequency output through the load stage. The bias current source in the frequency band separation amplifier is responsible for providing a suitable bias to the input transconductance stage, and the common-mode feedback network is used to stabilize the common-mode level at the output end.

[0026] The frequency band separation amplifier disclosed in the present invention can be single-ended input and single-ended output; it can also be differential input and differential output; the frequency band separation amplifier with single-ended input can be applied to a wake-up receiver using a self-mixer with single-ended output, and the frequency band separation amplifier with differential input can be applied to a wake-up receiver using a self-mixer with differential output. The input transconductance stage can use NMOS transistors or PMOS transistors; the load stage can use PMOS active loads or NMOS active loads. The filter network can be a capacitor network or a combination of a capacitor network and a resistor network. The capacitor network can use a programmable capacitor array; the resistor network can use a programmable resistor array, or use polysilicon resistors, or use MOS tubes as pseudo resistors. The bias current source uses a current mirror to copy the current of the reference current source to provide a bias for the amplifier, and can use NMOS or PMOS to copy the current. The current mirror of the bias current source can use a single MOS tube to provide a certain copy current, or a programmable MOS tube array can be used to achieve the adjustable bias current, thereby achieving the adjustability of gain and frequency selection. The common-mode feedback network can use a resistor network or a high-gain op amp to stabilize the output common-mode level.

[0027] In the embodiments of the present disclosure, Figure 2 As shown, a frequency band separation amplifier with a differential structure in an embodiment of the present disclosure is shown, V in+ , V in- Represents the input signal, the input transconductance stage uses NMOS transistors M N1 、M N2 The load stage uses an active PMOS load to M P1 、M P2 , the filter network uses a pseudo-differential tail capacitor C BLK , the common-mode feedback network uses a resistor network R F1 , R F2 , the bias current source uses an adjustable current source I Bias IF output terminal (V IF,O+ , V IF,O-) is selected at the drain of the input transconductance stage, the filter capacitor C BLK A low-frequency zero and a pole are introduced into the intermediate frequency path. The intermediate frequency output end has a pole determined by the load capacitance, and the overall characteristic is a bandpass characteristic. DC,O+ , V DC,O- ) is selected at the source of the output transconductance stage, and the band separation amplifier works in a source follower-like form. The transfer function has only one pole at the output end, which is mainly determined by the load capacitance and CBLK, and the overall low-pass characteristic is achieved, thereby achieving band separation.

[0028] In the embodiments of the present disclosure, Figure 3 As shown, another differential structure frequency band separation amplifier in the embodiment of the present disclosure is shown, V in+ , V in- Represents the input signal, the input transconductance stage uses NMOS transistors M N1 、M N2 The load stage uses an active PMOS load to M P1 、M P2 , the filter network uses a capacitor and resistor network C BLK and R B1 , R B2 , the common-mode feedback network uses high-gain op amps OP1 and OP2, V CM,REF represents the common-mode reference voltage, and the bias current source adopts an adjustable current source I Bias IF output terminal (V IF,O+ , V IF,O- ) is selected at the drain of the input transconductance stage, capacitor C BLK and resistor R B1 (or R B2 ) determines the position of the low-frequency zero point in the intermediate frequency transmission path. The gate of the active PMOS load pair has a gate composed of C BLK The pole determined by the transistor transconductance, the intermediate frequency output end has a pole determined by the load capacitance, and the overall bandpass characteristic; the low frequency output end (V DC,O+ , V DC,O- ) is selected at the gate of the active load transistor, and the transfer function has only one pole which is mainly determined by CBLK and the transistor transconductance, and the overall low-pass characteristic is achieved, thus achieving frequency band separation.

[0029] The present disclosure also provides the application of the above-mentioned frequency band separation amplifier in a receiver and an IOT communication system involving multiple down-conversion operations, for example, it can be applied to a receiver with a multiple down-conversion architecture to replace the functions of a filter and an amplifier, thereby at least eliminating two modules, an intermediate frequency bandpass filter and an intermediate frequency amplifier. The frequency band separation amplifier can play the role of filtering and amplification, and has the advantages of low power consumption and small size, reducing system costs and improving system integration.

[0030] So far, the embodiments of the present disclosure have been described in detail in conjunction with the accompanying drawings. It should be noted that the implementation methods not shown or described in the drawings or the body of the specification are all forms known to ordinary technicians in the relevant technical field and are not described in detail. In addition, the above definitions of each element and method are not limited to the various specific structures, shapes or methods mentioned in the embodiments, and ordinary technicians in the field can simply change or replace them.

[0031] According to the above description, those skilled in the art should have a clear understanding of the frequency band separation amplifier and its application disclosed in the present invention.

[0032] In summary, the present disclosure provides a frequency band separation amplifier and application, which has two transmission paths with different filtering characteristics, can effectively separate the intermediate frequency signal and the low frequency signal, avoids the use of multiple filters, and only requires a simple mathematical conversion relationship to obtain the relative signal strength relationship between the intermediate frequency component and the low frequency component. The frequency band separation amplifier has a simple structure and can be implemented by stacking at least three transistors. It has extremely high adaptability to low power supply voltage and low power consumption wake-up receiver circuits. The bias current source and filter network of the frequency band separation amplifier can be made into an adjustable array, and the overall gain and filtering characteristics have excellent adjustability.

[0033] It should be noted that, in this document, unless otherwise specified, “a” element is not limited to a single element, but may include one or more elements.

[0034] In addition, in this document, unless otherwise specified, ordinal numbers such as "first" and "second" are only used to distinguish multiple components with the same name, and do not indicate that there is a hierarchy, level, execution order, or process order between them. A "first" component and a "second" component may appear together in the same component, or appear in different components. The presence of a component with a larger ordinal number does not necessarily indicate the presence of another component with a smaller ordinal number.

[0035] In this document, unless otherwise specified, the so-called feature A "or" or "and / or" (and / or) feature B means that A exists alone, B exists alone, or A and B exist at the same time; the so-called feature A "and" (and) or "and" (and) or "and" (and) feature B means that A and B exist at the same time; the so-called "include", "comprise", "have" and "contain" mean including but not limited to these.

[0036] In addition, in this document, the terms "upper", "lower", "left", "right", "front", "back", or "between" are only used to describe the relative positions between multiple elements, and can be extended to include translation, rotation, or mirroring. In addition, in this document, unless otherwise specified, "an element is on another element" or similar descriptions do not necessarily mean that the element contacts the other element.

[0037] In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to the above list, and can be changed or rearranged according to the required design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0038] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A frequency band separation amplifier with a differential structure used in a receiver and an IOT communication system involving multiple down-conversion operations, comprising: Input transconductance stage, using NMOS transistors to NMOS tube M N1 and NMOS tube M N2 , used to convert the input signal including the low-frequency component and the intermediate-frequency component into two current signals; Bias current source, using adjustable current source I Bias , used to provide suitable bias for the input transconductance stage; The filter network uses capacitor C BLK , resistor R B1 , resistor R B2 The composition is configured to include two different transmission paths, a low-frequency transmission path and an intermediate-frequency transmission path, and different transmission zero poles are introduced into different transmission paths, so that the low-frequency transmission path presents a low-pass characteristic and the intermediate-frequency transmission path presents a band-pass characteristic, thereby outputting a low-frequency signal and an intermediate-frequency signal; Load level, using active PMOS load to PMOS tube M P1 And PMOS tube M P2 , low frequency signal and intermediate frequency signal are output through the load stage to obtain low frequency output and intermediate frequency output; as well as The common-mode feedback network uses high-gain operational amplifiers OP1 and OP2 to stabilize the common-mode levels of the low-frequency output and the intermediate-frequency output at the output end; The bias current source uses a current mirror to copy the current of the reference current source to provide a bias for the amplifier. The current mirror of the bias current source can use a single MOS tube to provide a certain copy current, or a programmable MOS tube array to achieve adjustable bias current, thereby achieving adjustability of gain and frequency selection; PMOS tube M P1 And PMOS tube M P2 The drain of NMOS tube M N1 and NMOS tube M N2 The drain of the intermediate frequency negative output terminal V IF,O- and the intermediate frequency positive output terminal V IF,O+ Select NMOS tube M N1 and NMOS tube M N2 The drain of NMOS tube M N1 and NMOS tube M N2 The gates receive the differential positive input signal V in+ and the differential negative input signal V in- , NMOS tube M N1 and NMOS tube M N2 The sources of the two terminals are connected together to an adjustable current source I Bias Grounded at the back; low frequency negative output terminal V DC,O- and the low frequency positive output terminal V DC,O+ Select PMOS tube M P1 、PMOS tube M P2 The gate of the capacitor CBLK is connected to the two ends of the resistor R B1 The two ends of the low frequency negative output terminal V DC,O- and the intermediate frequency negative output terminal V IF,O- , resistor R B2 The two ends are connected to the low frequency positive output terminal V DC,O+ and the intermediate frequency positive output terminal V IF,O+ The output of the operational amplifier OP1 is connected to the PMOS tube M P1 The gate of the IF is connected to the negative output terminal V IF,O- The negative input terminal is connected to the common mode reference voltage; the output terminal of the operational amplifier OP2 is connected to the PMOS tube M P2 The gate of the IF is connected to the positive input terminal of the IF positive output terminal V IF,O+ , the negative input terminal is connected to the common-mode reference voltage.

2. According to the frequency band separation amplifier of claim 1, the input transconductance stage can also use PMOS transistors; the load stage can also use NMOS active loads. 3 . The band separation amplifier according to claim 1 , wherein the filter network comprises a capacitor network or a combination of a capacitor network and a resistor network.

4. According to the frequency band separation amplifier of claim 3, the capacitor network can use a programmable capacitor array; the resistor network can use a programmable resistor array, or use polysilicon resistors, or use MOS tubes as pseudo resistors. 5 . The frequency band separation amplifier according to claim 1 , wherein the bias current source can also use an NMOS or PMOS replica current. 6 . The frequency band separation amplifier according to claim 1 , wherein the common mode feedback network uses a resistor network to stabilize the output common mode level.

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