Ultra-high precision dB-linear programmable gain amplifier based on resistive attenuator

Abstract

The application provides an ultra-high-precision dB-linear programmable gain amplifier based on a resistance attenuator, the resistance attenuator in the coarse adjustment gain unit is composed of the same resistance, and attenuation determined by the ratio between the resistances is provided; the gain generated in the fine adjustment gain unit is controlled by the ratio between transconductances, the coarse adjustment gain unit and the fine adjustment gain unit of the application can both generate strictly fixed voltage gain, so that the PGA is not sensitive to P-V-T changes. Therefore, the application has the advantages of low gain step, small gain error, small gain step, large gain range, low power consumption and the like, and is suitable for high-precision PGAs for high-frequency applications.

Description

Technical Field

[0001] This invention belongs to the field of integrated circuit technology, specifically relating to an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator. Background Technology

[0002] In recent years, with the development of big data analytics and artificial intelligence, the demands on signal processing speeds have increased rapidly, and the bandwidth of received signals has continued to grow. This necessitates Automatic Generation Control (AGC) circuits to adapt to a wide range of signal bandwidths, operating frequencies, and power requirements. Variable Gain Amplifiers (VGAs) and Programmable Gain Amplifiers (PGAs) offer linear decibel control, ensuring relatively constant received signal strength and settling time for most AGC circuits.

[0003] In existing technologies, most automatic gain control (AGC) is performed by digital signal processing units (DSPs). Compared to continuous mode VGAs, PGAs offer superior performance by eliminating the additional circuitry required to convert digital control signals to analog signals, thus requiring less chip area. However, existing dB (decibel) linear programmable gain amplifiers (PGAs) based on R-0.5R resistor attenuators only occupy the negative half-axis when fitted to a pseudo-exponential function, resulting in insufficient accuracy and poor performance. Summary of the Invention

[0004] To address the aforementioned problems in the prior art, this invention provides an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator. The technical problem to be solved by this invention is achieved through the following technical solution:

[0005] The present invention provides an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator, comprising: a gain coarse adjustment control unit, a gain fine adjustment control unit, a fixed gain unit, and an output buffer cascaded in sequence; the gain coarse adjustment control unit includes a resistor attenuator;

[0006] The resistor attenuator is used to output the voltage signals from the two input terminals to the two corresponding input terminals of the gain fine-tuning control unit by controlling the node voltage output through multiple switches, with the resistance between multiple nodes remaining constant and the node voltage attenuating as the distance between the node and the input terminal increases.

[0007] The gain fine-tuning control unit takes its own input voltage signal and passes it through transconductance and transimpedance amplifiers, and controls the source load of the transconductance amplifier to form an output signal that meets dB linearity characteristics, which is then output to the fixed gain unit.

[0008] A fixed gain unit is used to maintain the gain of its input signal constant and output it to the output buffer;

[0009] An output buffer is used to increase the current of the input signal before output.

[0010] Optionally, the resistor attenuator includes two node circuits, with the switch controlling the voltage of the first node corresponding to the switch controlling the voltage of the second node, and they are turned on or off simultaneously; the corresponding voltage of the first node is a fixed multiple of the voltage of the second node, and the fixed multiple is the same as the resistance value at the first node.

[0011] Optionally, the resistor attenuator includes multiple first resistors R, two second resistors 0.5R, multiple third resistors 0.75R, and multiple switches;

[0012] In each node circuit, every N first resistors R are connected in series with one second resistor 0.5R. In the two node circuits, two third resistors 0.75R are connected in series between the nth node Vn, and two second resistors 0.5R are connected in series. In each node circuit, the first terminal of the first resistor R is the input terminal of the resistor attenuator. In the first node circuit, the first terminal of the nth first resistor R is connected to one terminal of the nth switch An, and the other terminal of the nth switch An is connected to the first input terminal of the strip gain control. In the second node circuit, except for the first first resistor R, the first terminal of the nth first resistor R is connected to one terminal of the nth switch Bn, and the other terminal of the nth switch Bn is connected to the second input terminal of the strip gain control. The terminals of the two third resistors 0.75R connected to each other and the terminals of the two second resistors 0.5R connected to each other between the two nodes are connected to the power supply ground.

[0013] In the first node circuit, the nth switch and the (n+1)th switch in the second node circuit are simultaneously turned on or off.

[0014] Optionally, the gain fine-tuning control unit includes: transconductance amplifiers GM1 and GM2 with identical internal structures, and a transimpedance amplifier A connecting transconductance amplifiers GM1 and GM2. R ;

[0015] Both transconductance amplifiers GM1 and GM2 include two identical amplifier subunits, each containing a MOSFET differential pair M1 and a MOSFET differential pair M2. a1 A current source; the two gates of the MOSFET differential pair M1 and the MOSFET differential pair M a1 The two gates are connected correspondingly; the differential pair of the MOS transistors M a1After the two sources of the transistor are connected to the corresponding two sources of the differential pair M1 of the MOSFET, they are connected to the positive terminal of the current source, and the negative terminal of the current source is connected to the power supply ground; the two gates of the differential pair M1 of the MOSFET in one amplifier subunit of the transconductance amplifier GM1 are the first differential positive input terminal V. IP1 and V IN1 Then, the two gates of the differential pair M1 of the MOS transistor in the other amplifier subunit are the differential negative input terminals V. OP and V ON In the GM2 amplifier subunit, the two gates of the differential pair M1 of the MOS transistors are the second differential positive input terminal V. IP2 and V IN2 Then, the two gates of the differential pair M1 of the MOS transistor in the other amplifier subunit are the differential negative input terminals V. OP and V ON The first differential negative input terminal V OP and V ON Connect transimpedance amplifier A R Output terminal V OUT In each amplifier subunit, one of the two drains of the differential pair M1 of the MOS transistors serves as the first output terminal V. OP1 One serves as the second output terminal V OP2 Connected to transimpedance amplifier A R The input terminal.

[0016] Optional, transimpedance amplifier A R Includes: MOSFETs M5 to M 12 And common-mode feedback unit CMFB; M5 and M6, M7 and M8, M9 and M 10 M 11 With M 12 These form MOSFET pairs, with the gates of each pair connected together; the drain of M5 is connected to the source of M7, the drain of M7 is connected to the drain of M9, and the source of M9 is connected to the source of M7. 11 The drain of M6 is connected to the source of M8, and the drain of M8 is connected to the source of M8. 10 The drain connection, M 10 The source and M 12 Drain connection; M 11 The source and M 12 The source of M5 is connected to the power supply ground, and the source of M6 is connected to the power supply voltage; the output of the common-mode feedback unit CMFB is connected to the gate of M5 and M6; the input of the common-mode feedback unit CMFB is connected to the negative differential input V. OP and V ON .

[0017] Optional, M5 and M6, M7 and M8, M9 and M 10 M 11 and M12 They are all the same size, and the common-mode feedback unit (CMFB) is used to stabilize the common-mode level. The current provided by the current source in each amplifier subunit is the same.

[0018] Optionally, the fixed gain unit includes: a MOSFET differential pair Mn and Mp, and a current source;

[0019] In the differential pair Mn, the gates of the two MOS transistors are connected together, the source is connected to the power supply voltage, and the drain of each transistor is connected to the drain of one of the MOS transistors in the differential pair Mn as an output terminal connected to the buffer; in the differential pair Mp, the gates of the two MOS transistors are respectively connected to one output terminal of the gain fine-tuning control unit, the two gates are connected to the positive terminal of the current source, and the negative terminal is connected to the power supply ground.

[0020] Optionally, all MOS transistor differential pairs in the coarse gain control unit, fine gain control unit, fixed gain unit, and output buffer are designed using 0.18μm CMOS process.

[0021] The beneficial effects of this invention are:

[0022] This invention provides an ultra-high precision dB-linear programmable gain amplifier based on resistor attenuators. The resistor attenuator in the coarse-tuning gain unit consists of identical resistors, providing attenuation determined by the ratio between the resistors. The gain generated in the fine-tuning gain unit is controlled by the ratio between the transconductances. Both the coarse-tuning and fine-tuning gain units of this invention can produce strictly fixed voltage gains, making the PGA insensitive to PVT variations. Therefore, this invention has advantages such as low gain step, extremely small gain error, small gain step size, large gain range, and low power consumption, making it suitable for high-precision PGAs in high-frequency applications.

[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0024] Figure 1 This is a circuit block diagram of an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator provided in an embodiment of the present invention;

[0025] Figure 2 This is a schematic diagram of the coarse-adjustment gain control circuit and the fine-adjustment gain control circuit of an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator provided in an embodiment of the present invention.

[0026] Figure 3 This is a circuit topology diagram of a fine-tuning gain control unit within an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator, provided in an embodiment of the present invention.

[0027] Figure 4 This is a circuit topology diagram of a fixed gain control unit within an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator, provided by an embodiment of the present invention.

[0028] Figure 5 This is a schematic diagram illustrating the characteristics of a pseudo-exponential function curve provided by an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram comparing the gain error of a circuit before and after optimization, provided by an embodiment of the present invention;

[0030] Figure 7 These are the gain and gain error curves finally obtained in the embodiments of the present invention. Detailed Implementation

[0031] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0032] like Figure 1 As shown, the present invention provides an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator, comprising: a gain coarse adjustment control unit, a gain fine adjustment control unit, a fixed gain unit, and an output buffer cascaded in sequence; the gain coarse adjustment control unit includes a resistor attenuator;

[0033] The resistor attenuator is used to output the voltage signals from the two input terminals to the two corresponding input terminals of the gain fine-tuning control unit by controlling the node voltage output through multiple switches, with the resistance between multiple nodes remaining constant and the node voltage attenuating as the distance between the node and the input terminal increases.

[0034] The resistor attenuator includes two node circuits. The switch controlling the voltage of the first node corresponds one-to-one with the switch controlling the voltage of the second node, and they are turned on or off simultaneously. The corresponding voltage of the first node is a fixed multiple of the voltage of the second node, and the fixed multiple is the same as the resistance value at the first node.

[0035] The gain fine-tuning control unit takes its own input voltage signal and passes it through transconductance and transimpedance amplifiers, and controls the source load of the transconductance amplifier to form an output signal that meets dB linearity characteristics, which is then output to the fixed gain unit.

[0036] A fixed gain unit is used to maintain the gain of its input signal constant and output it to the output buffer;

[0037] An output buffer is used to increase the current of the input signal before output.

[0038] The output buffer is an operational amplifier with a gain close to 1.

[0039] refer to Figure 2 , Figure 2 This is a schematic diagram of the coarse-adjustment gain control unit and fine-adjustment gain control unit circuit of an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator, provided by an embodiment of the present invention. It includes a coarse-adjustment gain control unit and a fine-adjustment gain control unit.

[0040] Specifically, the voltage input terminal V of the coarse adjustment gain control unit IP V IN It is the total voltage input terminal of an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator, and the voltage input terminal V of the coarse-tuning gain control unit. IP V IN It is the voltage input terminal of the input buffer, and the two are 180° out of phase.

[0041] refer to Figure 2 The resistor attenuator includes multiple first resistors R, two second resistors 0.5R, multiple third resistors 0.75R, and multiple switches;

[0042] In each node circuit, every N first resistors R are connected in series with one second resistor 0.5R. In the two node circuits, two third resistors 0.75R are connected in series between the nth node Vn, and two second resistors 0.5R are connected in series. In each node circuit, the first terminal of the first resistor R is the input terminal of the resistor attenuator. In the first node circuit, the first terminal of the nth first resistor R is connected to one terminal of the nth switch An, and the other terminal of the nth switch An is connected to the first input terminal of the strip gain control. In the second node circuit, except for the first first resistor R, the first terminal of the nth first resistor R is connected to one terminal of the nth switch Bn, and the other terminal of the nth switch Bn is connected to the second input terminal of the strip gain control. The terminals of the two third resistors 0.75R connected to each other and the terminals of the two second resistors 0.5R connected to each other between the two nodes are connected to the power supply ground.

[0043] In the first node circuit, the nth switch and the (n+1)th switch in the second node circuit are simultaneously turned on or off.

[0044] It is worth noting that: when viewed from each terminal of the resistor attenuator, the resistance value on the right side is 3R. Therefore, the voltage value at each terminal is three times the voltage value at the next terminal, i.e., V1 = 3V2 = 9V3 = 27V4 = 81V5 = 243V6. The terminals V1 to V5 of the resistor attenuator are connected to switches A1 to A5, and the terminals V2 to V6 are connected to switches B1 to B5. Switches A1 to A5 and B1 to B5 correspond to each other and can be opened or closed simultaneously. When switches A1 to A5 and B1 to B5 are closed, only two corresponding switches are closed. For example, A1 and B1 are closed simultaneously, while the other switches A2 to A5 and B2 to B5 are open to ensure that the voltage of input switch A is three times the voltage of input switch B.

[0045] The voltage input terminal V of the fine-tuning gain control unit A1 and V B1 They are connected to switches A1-A5 and B1-B5 respectively. Since the voltage at input switch A is three times the voltage at input switch B, the voltage input terminal V... A1 =3V B1 ;

[0046] Combination Figure 3 , Figure 3 This is a circuit topology diagram of a fine-tuning gain control unit for an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator, provided in an embodiment of the present invention. The fine-tuning gain control unit includes: transconductance amplifiers GM1 and GM2 with identical internal structures, and a transimpedance amplifier A connecting GM1 and GM2. R ;

[0047] Both transconductance amplifiers GM1 and GM2 include two identical amplifier subunits, each containing a MOSFET differential pair M1 and a MOSFET differential pair M2. a1 A current source; the two gates of the MOSFET differential pair M1 and the MOSFET differential pair M a1 The two gates are connected correspondingly; the differential pair of the MOS transistors M a1 After the two sources of the transistor are connected to the corresponding two sources of the differential pair M1 of the MOSFET, they are connected to the positive terminal of the current source, and the negative terminal of the current source is connected to the power supply ground; the two gates of the differential pair M1 of the MOSFET in one amplifier subunit of the transconductance amplifier GM1 are the first differential positive input terminal V. IP1 and V IN1 Then, the two gates of the differential pair M1 of the MOS transistor in the other amplifier subunit are the differential negative input terminals V. OP and V ON In the GM2 amplifier subunit, the two gates of the differential pair M1 of the MOS transistors are the second differential positive input terminal V. IP2and V IN2 Then, the two gates of the differential pair M1 of the MOS transistor in the other amplifier subunit are the differential negative input terminals V. OP and V ON The first differential negative input terminal V OP and V ON Connect transimpedance amplifier A R Output terminal V OUT In each amplifier subunit, one of the two drains of the differential pair M1 of the MOS transistors serves as the first output terminal V. OP1 One serves as the second output terminal V OP2 Connected to transimpedance amplifier A R The input terminal.

[0048] refer to Figure 3 Transimpedance amplifier A R Includes: MOSFETs M5 to M 12 And common-mode feedback unit CMFB; M5 and M6, M7 and M8, M9 and M 10 M 11 With M 12 These form MOSFET pairs, with the gates of each pair connected together; the drain of M5 is connected to the source of M7, the drain of M7 is connected to the drain of M9, and the source of M9 is connected to the source of M7. 11 The drain of M6 is connected to the source of M8, and the drain of M8 is connected to the source of M8. 10 The drain connection, M 10 The source and M 12 Drain connection; M 11 The source and M 12 The source of M5 is connected to the power supply ground, and the source of M6 is connected to the power supply voltage; the output of the common-mode feedback unit CMFB is connected to the gate of M5 and M6; the input of the common-mode feedback unit CMFB is connected to the negative differential input V. OP and V ON .

[0049] Combined with Figure 2 It can be seen that the voltage input terminal V of the fine-tuning gain control unit A1 and V B1 The positive voltage inputs of transconductance amplifiers GM1 and GM2 are connected to each other, and the negative voltage inputs of transconductance amplifiers GM1 and GM2 are connected to the output V of the fine-tuning gain unit. OUT Connected, the output terminals V of transconductance amplifiers GM1 and GM2 O1 V O2 With transimpedance amplifier A R The input terminals are connected to the transimpedance amplifier A. R The output terminal and the voltage output terminal V of the fine-tuning gain control unit. OUT Connected.

[0050] Among them, M5 and M6, M7 and M8, M9 and M 10 M 11 and M 12 They are all the same size, and the common-mode feedback unit (CMFB) is used to stabilize the common-mode level. The current provided by the current source in each amplifier subunit is the same.

[0051] Combined with Figure 2 and Figure 3 The differential voltage positive input terminal V of transconductance amplifier GM1 IP1 and V IN1 This is the positive input terminal V of the fine-tuning gain control unit. A1 The differential voltage negative input terminal V of transconductance amplifier GM1 OP and V ON Connect the output terminal V of the fine-tuning gain control unit OUT The differential voltage output terminal V of the transconductance amplifier GM1 OP1 and V ON1 V O1 and V O2 Connect to the differential input terminal of the transimpedance amplifier; the transconductance amplifier GM1 mainly consists of MOSFET differential pairs M1, M2, and M... a1 M a2 It consists of current source I1 and current source I2, where M1 and M2 have the same size. a1 and M a2 They are the same size, and current sources I1 and I2 provide the same amount of current.

[0052] The differential voltage positive input terminal V of transconductance amplifier GM2 IP2 and V IN2 This is the positive input terminal V of the fine-tuning gain control unit. B1 The differential voltage negative input terminal V of transconductance amplifier GM2 OP and V ON Connect the output terminal V of the fine-tuning gain control unit OUT The differential voltage output terminal V of the transconductance amplifier GM2 OP1 and V ON1 V O1 and V O2 Connect transimpedance amplifier A R The differential input terminal; the transconductance amplifier GM2 mainly consists of MOSFET differential pairs M3, M4, and M... a3 M a4 It consists of current source I3 and current source I4, where M3 and M4 have the same size. a3 and M a4 They are the same size, and current sources I3 and I4 provide the same amount of current.

[0053] Transimpedance amplifier A R The differential voltage input terminal is V OP1 and V ON1 This refers to V in the fine-tuning gain control unit. O1 and V O2 Transimpedance amplifier A R The output terminal is V OP and V ON This refers to the output terminal V of the fine-tuning gain control unit. OUT Transimpedance amplifier A R The differential pair of MOS transistors M5 to M 12 It consists of a common-mode feedback unit (CMFB), where M5 and M6, M7 and M8, and M9 and M... 10 M 11 and M 12 With identical dimensions, the common-mode feedback unit (CMFB) is primarily used to stabilize the common-mode level.

[0054] See Figure 4 , Figure 4 This is a circuit topology diagram of a fixed gain control unit within an ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator, provided by an embodiment of the present invention. The fixed gain unit includes: a differential pair of MOS transistors Mn and Mp, and a current source;

[0055] In the differential pair Mn, the gates of the two MOS transistors are connected together, the source is connected to the power supply voltage, and the drain of each transistor is connected to the drain of one of the MOS transistors in the differential pair Mn as an output terminal connected to the buffer; in the differential pair Mp, the gates of the two MOS transistors are respectively connected to one output terminal of the gain fine-tuning control unit, the two gates are connected to the positive terminal of the current source, and the negative terminal is connected to the power supply ground.

[0056] Combination Figure 3 and Figure 4 The differential voltage input V of the fixed gain unit can be obtained. IP and V IN Connect the output terminals V of the thin strip gain unit respectively OP and V ON The fixed gain unit mainly consists of a differential pair of MOS transistors M n and M p It consists of a current source.

[0057] In this embodiment of the invention, all differential pairs of MOS transistors in the coarse gain control unit, fine gain control unit, fixed gain unit and buffer are designed using 0.18μm CMOS process.

[0058] This invention provides an ultra-high precision dB-linear programmable gain amplifier based on resistor attenuators. The resistor attenuator in the coarse-tuning gain unit consists of identical resistors, providing attenuation determined by the ratio between the resistors. The gain generated in the fine-tuning gain unit is controlled by the ratio between the transconductances. Both the coarse-tuning and fine-tuning gain units of this invention can produce strictly fixed voltage gains, making the PGA insensitive to PVT variations. Therefore, this invention has advantages such as low gain step, extremely small gain error, small gain step size, large gain range, and low power consumption, making it suitable for high-precision PGAs in high-frequency applications.

[0059] The structural principle and the effects that can be achieved by this invention will be analyzed below.

[0060] In this embodiment, the topology of the gain control unit is finely adjusted as follows: Figure 3 As shown, assume the transconductances of GM1 and GM2 are G... m1 and G m2 Then the transimpedance of the transimpedance amplifier is A. R By fine-tuning the control unit, the following relationship can be obtained:

[0061] [Gm1(V1-V out )+Gm2(V2-V out A R =V out #(1)

[0062] From the relationship of the resistor attenuator mentioned above, we know that V1 = 3V2, and due to the transimpedance A of the transimpedance amplifier... R If it is large enough, then the DC voltage gain A V It can be represented as:

[0063]

[0064] Using source negative feedback technology, the total transconductance of the transconductance amplifier can be changed. Since the two sets of transconductance amplifiers in GM1 and GM2 are of the same size, this technology can be used to change the total transconductance of G. m1 and G m2 Represented as

[0065]

[0066]

[0067] Among them, the differential pairs of MOSFETs M1 to M4 are in the saturation region, and the differential pair of MOSFETs M that acts as the source negative feedback resistor is... a1 ~M a4 Located in the deep linear region, its transconductance values ​​are g mn =μ n C ox (W / L)n (V gs -V th ), g man =μ n C ox (W / L) n (V gs -V th Therefore, g mn / g man =k n , and k 1,2 =k 3,4 Where n = 1 to 4. Substituting formulas (3) and (4) into formula (2) yields:

[0068]

[0069] If this invention assumes (1+k) 3,4 ) = S, (1+k 1,2 ) = 7 - S, where S = 1 to 6, therefore the gain A V It can be rewritten as:

[0070]

[0071] The characteristics of pseudo-exponential functions are as follows: Figure 5 As shown, it is clear that the gain error is symmetrical about the origin, and the rate of increase of the gain error increases with increasing t. Therefore, if t is far from the origin, there is a problem of a large gain error. Figure 5 As shown, the gain error from t to 0.5 is nine times that from t to 0.25. This means that if the present invention can shift t to make it symmetrical about the origin, then the error will be minimized. Based on this property of the pseudo-indicator function, the present invention introduces an optimization factor β into the voltage gain A. V In this context, the voltage gain can be re-expressed as

[0072]

[0073] The voltage gain in (7) follows the pseudo-exponential function A v = (1+t) / (1-t)≈e 2t The variation is adjusted to achieve a dB-linear gain, thus yielding t:

[0074]

[0075] If (1+β)g m1,2 =(1 / 3+β)g m3,4Then, a linear relationship can be maintained between t and S. Introducing the optimization factor β allows t0 to move instead of remaining solely on one side of the origin, which means improved accuracy. Furthermore, this invention can move t to a position symmetrical about the origin using the formula t(0) + t(7) = 0. This can then be substituted into (8) to calculate β = √3 / 3. Finally, t can be expressed as...

[0076]

[0077] The gain error of PGA before and after introducing the optimization factor is as follows: Figure 6 As shown in the diagram. Clearly, the gain error of the optimized PGA is much lower than that of the traditional PGA, approximately only 1 / 8 of the original. Then, this invention cascades a fixed-gain unit with constant gain afterward to further improve its gain, as shown in the diagram. Figure 4 As shown.

[0078] Ultimately, the ultra-high precision PGA based on resistor attenuators achieved by this invention not only has low gain step and extremely small gain error, i.e., very high precision, but its precision curve is as follows: Figure 7 As shown. Simultaneously, the resistor attenuators within the coarse-tuning gain unit consist of identical resistors and provide attenuation determined by the ratio between the resistors, while the gain generated within the fine-tuning gain unit is controlled by the ratio between the transconductances. Both contribute to producing a strictly fixed voltage gain and make the PGA insensitive to PVT variations. Ultimately, this invention achieves a high-precision PGA with small gain steps, a large gain range, low power consumption, and suitability for high-frequency applications.

[0079] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A high-precision dB-linear programmable gain amplifier based on a resistor attenuator, characterized in that, include: The gain coarse adjustment control unit, gain fine adjustment control unit, fixed gain unit, and output buffer are cascaded in sequence. The gain coarse adjustment control unit includes a resistor attenuator; The resistor attenuator is used to output the voltage signals of the two input terminals to the two corresponding input terminals of the gain fine-tuning control unit by controlling the node voltage through multiple switches, with the resistance between multiple nodes remaining constant and the node voltage attenuating as the distance between the node and the input terminal increases. The gain fine-tuning control unit takes its input voltage signal and passes it through transconductance and transimpedance amplifiers, controls the source load of the transconductance amplifier to adjust the transconductance ratio, introduces an optimization factor to optimize the voltage gain, and forms an output signal that meets dB linearity characteristics, which is then output to the fixed gain unit. The gain fine-tuning control unit includes: transconductance amplifiers GM1 and GM2 with identical internal structures, and a transimpedance amplifier A connecting transconductance amplifiers GM1 and GM2. R ; The optimized voltage gain is expressed as follows: ； In the formula, This represents the optimized voltage gain. This represents the transconductance coefficient of the transconductance amplifier GM1. This represents the transconductance value of the transconductance amplifier GM2. Indicates the control state variable. Indicates the optimization factor; The fixed gain unit is used to maintain the gain of its own input signal unchanged and output to the output buffer; The output buffer is used to increase the current of the input signal before outputting it.

2. The ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator according to claim 1, characterized in that, The resistor attenuator includes two node circuits. The switch controlling the voltage of the first node corresponds one-to-one with the switch controlling the voltage of the second node, and they are turned on or off simultaneously. The corresponding voltage of the first node is a fixed multiple of the voltage of the second node, and the fixed multiple is the same as the resistance value at the first node.

3. The ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator according to claim 2, characterized in that, The resistor attenuator includes multiple first resistors (R), two second resistors (0.5R), multiple third resistors (0.75R), and multiple switches; In each node circuit, every N first resistors (R) are connected in series with one second resistor (0.5R). Between the nth node (Vn) in both node circuits, two third resistors (0.75R) are connected in series, and the two second resistors (0.5R) are connected together. In each node circuit, the first terminal of the first resistor (R) is the input terminal of the resistor attenuator. In the first node circuit, the first terminal of the nth first resistor (R) is connected to one terminal of the nth switch (An), and the other terminal of the nth switch (An) is connected to the first input terminal of the stripe gain control. In the second node circuit, except for the first first resistor (R), the first terminal of the nth first resistor (R) is connected to one terminal of the nth switch (Bn), and the other terminal of the nth switch (Bn) is connected to the second input terminal of the stripe gain control. The terminals of the two third resistors (0.75R) connected to each other and the two second resistors (0.5R) connected to each other between the two nodes are connected to the power supply ground. In the first node circuit, the nth switch and the (n+1)th switch in the second node circuit are simultaneously turned on or off.

4. The ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator according to claim 1, characterized in that, in, Both transconductance amplifiers GM1 and GM2 include two structurally identical amplifier subunits. Each amplifier subunit includes a differential pair of MOSFETs M1 and a differential pair of MOSFETs M2. a1 A current source; the two gates of the MOSFET differential pair M1 and the MOSFET differential pair M a1 The two gates are connected correspondingly; the differential pair of the MOS transistors M a1 After the two sources of the transistor are connected to the corresponding two sources of the differential pair M1 of the MOSFET, they are connected to the positive terminal of the current source, and the negative terminal of the current source is connected to the power supply ground; the two gates of the differential pair M1 of the MOSFET in one amplifier subunit of the transconductance amplifier GM1 are the first differential positive input terminal V. IP1 and V IN1 Then, the two gates of the differential pair M1 of the MOS transistor in the other amplifier subunit are the differential negative input terminals V. OP and V ON In the GM2 amplifier subunit, the two gates of the differential pair M1 of the MOS transistors are the second differential positive input terminal V. IP2 and V IN2 Then, the two gates of the differential pair M1 of the MOS transistor in the other amplifier subunit are the differential negative input terminals V. OP and V ON The first differential negative input terminal V OP and V ON Connect transimpedance amplifier A R Output terminal (V) OUT In each amplifier subunit, one of the two drains of the differential pair M1 of the MOS transistors serves as the first output terminal (V). OP1 ), one as the second output terminal (V OP2 Connected to transimpedance amplifier A R The input terminal.

5. The ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator according to claim 4, characterized in that, The transimpedance amplifier A R Including: MOSFETs M5~M 12 And common-mode feedback unit CMFB; M5 and M6, M7 and M8, M9 and M 10 M 11 With M 12 These form MOSFET pairs, with the gates of each pair connected together; the drain of M5 is connected to the source of M7, the drain of M7 is connected to the drain of M9, and the source of M9 is connected to the source of M7. 11 The drain of M6 is connected to the source of M8, and the drain of M8 is connected to the source of M8. 10 The drain connection, M 10 The source and M 12 Drain connection; M 11 The source and M 12 The source of M5 and M6 is connected to the power supply ground, and the source of M5 and M6 is connected to the power supply voltage; the output of the common-mode feedback unit CMFB is connected to the gate of M5 and M6; the input of the common-mode feedback unit CMFB is connected to the negative differential input V. OP and V ON .

6. The ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator according to claim 5, characterized in that, M5 and M6, M7 and M8, M9 and M 10 M 11 and M 12 They are all the same size, and the common-mode feedback unit (CMFB) is used to stabilize the common-mode level. The current provided by the current source in each amplifier subunit is the same.

7. The ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator according to claim 1, characterized in that, The fixed gain unit includes: a MOS transistor differential pair Mn and Mp, and a current source; In the differential pair Mn, the gates of the two MOS transistors are connected together, the source is connected to the power supply voltage, and the drain of each transistor is connected to the drain of one of the MOS transistors in the differential pair Mn as an output terminal connected to the buffer; in the differential pair Mp, the gates of the two MOS transistors are respectively connected to one output terminal of the gain fine-tuning control unit, the two gates are connected to the positive terminal of the current source, and the negative terminal is connected to the power supply ground.

8. The ultra-high precision dB-linear programmable gain amplifier based on a resistor attenuator according to claim 1, characterized in that, All differential pairs of MOS transistors in the coarse gain control unit, fine gain control unit, fixed gain unit, and output buffer are designed using 0.18μm CMOS technology.

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