CN110176908B - Switched capacitor integrator based on dynamic amplifier - Google Patents

Abstract

A switched capacitor integrator based on a dynamic amplifier, comprising: a dynamic amplifier for amplifying an input signal, the dynamic amplifier comprising an operational amplifier module and a tail current bias module, wherein the operational amplifier module is used to provide a predetermined amplification gain, and the tail current The bias module is used to provide bias current for the operational amplifier module to determine the DC operating point of the operational amplifier module; two switched capacitor networks, respectively set at the forward input end and the reverse input end of the dynamic amplifier, are used for the first In the second state, the input signal is sampled, and in the second state, the sampled signal is input to the dynamic amplifier; two integral capacitors are respectively connected to the forward input terminal and the reverse output terminal of the dynamic amplifier, as well as the reverse input terminal and the forward direction. The output terminal is used to integrate the sampled signal. Power consumption is greatly reduced by using dynamic amplifiers without capacitive loads.

Description

A Switched Capacitor Integrator Based on Dynamic Amplifier

technical field

The present disclosure relates to the technical field of integrated circuits, and in particular, to a switched capacitor integrator based on a dynamic amplifier.

Background technique

Switched capacitor integrators are widely used in analog filters and analog-to-digital converters. Traditional switched capacitor integrators based on dynamic amplifiers have high power consumption, while dynamic amplifiers have no static power consumption. The characteristics of their switching operations make them suitable for switching. Capacitive integrator. But ordinary dynamic amplifiers have capacitive loads, which add extra power consumption.

SUMMARY OF THE INVENTION

(1) Technical problems to be solved

Based on the above problems, the present disclosure provides a switched capacitor integrator based on a dynamic amplifier. The dynamic amplifier does not use a large load capacitance, which can reduce the power loss of the integrator and improve the gain of the integrator.

(2) Technical solutions

The present disclosure provides a switched capacitor integrator based on a dynamic amplifier, comprising: a dynamic amplifier for amplifying an input signal, including an operational amplifier module and a tail current bias module, wherein the operational amplifier module is used to provide a predetermined amplification gain, the tail current bias module is used to provide bias current for the operational amplifier module to determine the DC operating point of the operational amplifier module; two switched capacitor networks are respectively set at the forward input of the dynamic amplifier terminal and reverse input terminal, used for sampling the input signal in the first state, and inputting the sampled signal to the dynamic amplifier in the second state; two integrating capacitors, respectively connected to the dynamic amplifier The forward input end and the reverse output end and the reverse input end and the forward output end of the amplifier are used for integrating the sampled signal.

Optionally, the operational amplifier module includes four MOS field effect transistors, M ₁ , M ₂ , M _C1 and M _C2 respectively, and two MOS switches Φ _rst , the gates of the M ₁ and M ₂ are are respectively the reverse input terminal and the forward input terminal, the sources of M ₁ and M ₂ are connected, and the drain electrodes of M ₁ and M ₂ are respectively connected to the sources of M _C1 and M _C2 , The drains of the M _C1 and M _C2 are respectively the forward output terminal and the reverse output terminal, and are respectively connected to the reference voltage V _DD through a MOS switch Φ _rst , and the M _C1 is connected to the gate of the M _C2 . .

Optionally, the operational amplifier module further includes two bias capacitors, namely C _b1 and C _b2 , the C _b1 and C _b2 are connected in series, and the end connected to the C _b1 and C _b2 is connected to the M _C1 and C b2 . The gate of M _C2 is connected to the gate, the other end of the C _b1 is connected to the forward output end, and the other end of the C _b2 is connected to the reverse output end.

Optionally, the tail current bias module includes a MOS switch Φ _en , MOS field effect transistors M _T1 , M _T2 and a resistor R _B1 , and the gates of the M _T1 and M _T2 are connected to the resistor R after being connected. One end of _B1 is connected, the sources of _MT1 and _MT2 are connected to ground, the drain of _MT1 is connected to one end of the resistor _RB1 , and the other end of the resistor _RB1 is connected to a preset voltage , the drain of the M _T2 is connected to the sources of the M ₁ and M ₂ through the MOS switch Φ _en .

Optionally, each of the switched capacitor networks includes a capacitor C, a MOS switch Φ ₁ , a MOS switch Φ _1e , a MOS switch Φ ₂ and a MOS switch Φ _2e , and one end of the capacitor C is connected to the MOS switch Φ ₁ , The other end is connected to the forward input end or the reverse input end of the operational amplifier module through the MOS switch Φ _2e , and one end of the capacitor C is also connected to the first common-mode input voltage through the MOS switch Φ ₂ , the The other end of the capacitor C is also connected to the second common mode input voltage through the MOS switch Φ _1e .

Optionally, an external clock is also included for generating a clock signal to control the MOS switch Φ ₁ , MOS switch Φ _1e , MOS switch Φ ₂ , MOS switch Φ _2e , MOS switch Φ _rst and MOS switch Φ _en .

Optionally, the first state is that the MOS switch Φ _1e and the MOS switch Φ ₁ are in an operating state, the second state is that the MOS switch Φ _2e and the MOS switch Φ ₂ are in an operating state, and the second state is that the MOS switch Φ 2e and the MOS switch Φ 2 are in an operating state. A state operates after the first state.

Optionally, the MOS switch _Φ1e works ahead of the MOS switch Φ1, and its operating frequency is both _3.072 MHz; the MOS switch _Φ2e works ahead of the MOS switch Φ2, and its operating frequency is both _3.072 MHz.

Optionally, the MOS switch Φ _en continuously operates after the MOS switch Φ _rst , and the total operating interval of the MOS switch Φ _en and the MOS switch Φ _rst is consistent with the operating interval of the MOS switch Φ ₂ or Φ _2e .

Optionally, the operating frequency of the external clock is 6.144MHz.

(3) Beneficial effects

The switched capacitor integrator based on the dynamic amplifier provided by the present disclosure has the following beneficial effects:

(1) There is no large load capacitance in the dynamic amplifier of the present disclosure, which saves circuit area and complexity, and saves useless power consumption;

(2) By changing the traditional PMOS load in the dynamic amplifier to a MOS switch, the gain of the amplifier can be increased by about 2 times, the accuracy of the integrator can be improved, the swing of the amplifier can be increased, and the linearity of the integrator can be improved .

Description of drawings

FIG. 1 schematically shows a schematic structural diagram of a dynamic amplifier-based switched capacitor integrator provided by an embodiment of the present disclosure.

FIG. 2 schematically shows a detailed structural diagram of a dynamic amplifier provided by an embodiment of the present disclosure.

FIG. 3 schematically shows a schematic diagram of a working sequence of an external clock provided by an embodiment of the present disclosure.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

Switched capacitor integrator is a common analog circuit module, which is widely used in analog integrated filters and analog-to-digital converters. Traditional switched capacitor integrator circuits usually use ordinary dynamic amplifiers as active amplifying components, and their power consumption is often very high. Large, in an embodiment of the present disclosure, a dynamic amplifier based switched capacitor integrator is provided to reduce the power consumption of the integrator.

Referring to FIG. 1 , in conjunction with FIGS. 2 and 3 , the dynamic amplifier-based switched capacitor integrator in the present disclosure will be described in detail.

As shown in FIG. 1 , the switched capacitor integrator based on the dynamic amplifier in this embodiment includes a dynamic amplifier, two switched capacitor networks and two integrating capacitors.

The dynamic amplifier is used to amplify the input signal, which includes an operational amplifier module and a tail current bias module, wherein the dynamic amplifier is used to provide a predetermined gain to amplify the input signal, and the tail current bias module is used to provide bias current for the operational amplifier module , to determine the DC operating point of the operational amplifier module, so that the operational amplifier module starts to work, specifically, refer to FIG. 2 .

The operational amplifier module includes four MOS field effect transistors, namely M ₁ , M ₂ , M _C1 and M _C2 , and two MOS switches Φ _rst , wherein the four MOS field effect transistors form a cascode structure, which can be used in Provides greater gain without introducing additional poles. Compared with the traditional dynamic amplifier, the dynamic amplifier in this embodiment does not include a PMOS current source load, but is replaced by two reset MOS switches Φ _rst , which are used to reset the output voltage to the power supply voltage and set the initial conditions for the dynamic amplifier to work. . M ₁ and M ₂ are arranged adjacent to each other, the gates of M ₁ and M ₂ are respectively the reverse input terminal and the forward input terminal of the operational amplifier module, the sources of M ₁ and M ₂ are connected to each other, and the gates of M ₁ and M ₂ are connected to each other. The drains are respectively connected with the sources of M _C1 and M _C2 , and the drains of M _C1 and M _C2 are respectively the forward output terminal and the reverse output terminal, and are respectively connected to the reference voltage V _DD through a MOS switch Φ _rst , when When the MOS switch Φ _rst is turned on, the reverse output terminal and the forward output terminal of the operational amplifier module are reset to the reference voltage, and the gates of M _C1 and M _C2 are connected to each other.

The operational amplifier module further includes two bias capacitors, namely a capacitor C _b1 and a capacitor C _b2 , the capacitances of the two bias capacitors are relatively small, the capacitor C _b1 and the capacitor C _b2 are connected in series, and one end of the capacitor C _b1 is connected to the forward direction The output terminal Von is connected, and the other end of the capacitor C _b1 is connected to the gate of M _C1 or M _C2 ; one end of the capacitor C _b2 is connected to the reverse output terminal Vop, and the other end of the capacitor C _b2 is connected to the gate of M _C1 or M _C2 connect. It is used to provide a dynamic bias voltage for M _C1 or M _C2 because its small capacitance does not degrade the settling characteristics of the integrator.

The tail current bias module includes a MOS switch Φ _en , MOS field effect transistors M _T1 and M _T2 and a bias resistor R _B1 , the MOS field effect transistors M _T1 and M _T2 form a current mirror, and the gates of M _T1 and M _T2 After connection, it is connected to one end of the resistor R _B1 , the sources of M _T1 and M _T2 are connected to the ground, the drain of M _T1 is connected to one end of the resistor R _B1 , the other end of the resistor R _B1 is connected to a preset voltage, and the M _T2 The drain of M 1 is connected to the source of M ₁ and M ₂ through a MOS switch Φ _en . When the MOS switch Φ _rst is closed, the switch resets the forward output terminal Von and the reverse output terminal Vop to the reference voltage V _DD , and then when the MOS switch Φ _en is closed, the tail current bias module is connected to the circuit to provide sinking current, so that the dynamic amplifier starts to work.

The working phase of the dynamic amplifier disclosed in the embodiments of the present disclosure is divided into two parts: common mode and differential mode. In terms of common mode, the sinking current will pull down the voltages of Von and the reverse output terminal Vop until a suitable output common mode is reached. In terms of voltage, in the embodiment of the present disclosure, it is preferably V _DD /2. At the same time, a differential mode signal is input, and a differential mode output voltage can be established on the integrating capacitors C _Inp and C _Inn to complete the integration function.

Two switched capacitor networks, respectively set at the forward input terminal and the reverse input terminal of the dynamic amplifier, are used to sample the input signal in the first state, and input the sampled signal to the dynamic amplifier in the second state, Specifically, see FIG. 1 .

The two switched capacitor networks are respectively a forward input switched capacitor network and a reverse input switched capacitor network. The forward input switched capacitor network includes a capacitor C, a MOS switch Φ ₁ , a MOS switch Φ _1e , a MOS switch Φ ₂ and a MOS Switch Φ _2e , one end of the capacitor C is connected to the MOS switch Φ ₁ , the other end is connected to the forward input terminal or the reverse input terminal of the operational amplifier module through the MOS switch Φ _2e , and one end of the capacitor C is also connected to the first through the MOS switch Φ ₂ . The common mode input voltage is connected, and the other end of the capacitor C is also connected to the second common mode input voltage through the MOS switch Φ _1e ; the switched capacitor network of the reverse input terminal includes a capacitor C, a MOS switch Φ ₁ , a MOS switch Φ _1e , a MOS switch Φ ₂ and the MOS switch Φ _2e , one end of the capacitor C is connected to the MOS switch Φ ₁ , the other end is connected to the forward input terminal or the reverse input terminal of the operational amplifier module through the MOS switch Φ _2e , and one end of the capacitor C is also connected to the MOS switch Φ. ₂ is connected to the first common mode input voltage, and the other end of the capacitor C is also connected to the second common mode input voltage through the MOS switch Φ _1e . The first state is that the MOS switch Φ _1e and the MOS switch Φ ₁ are in the working state, and the input signal is sampled through the capacitor C at this time, and the second state is that the MOS switch Φ _2e and the MOS switch Φ ₂ are in the working state, and the capacitor C The sampled signal is transferred to the integrating capacitor and amplified, and the second state operates after the first state.

The two integrating capacitors are respectively connected to the forward input terminal and the reverse output terminal of the dynamic amplifier and to the reverse input terminal and the forward output terminal of the dynamic amplifier, and are used for integrating the sampled signal. Specifically, the two integrating capacitors in this embodiment are C _Inp and C _Inn respectively, wherein C _Inp is connected between the reverse input terminal and the forward output terminal of the dynamic amplifier, and C _Inn is connected across the forward input terminal of the dynamic amplifier and the reverse output.

In this embodiment, the switched capacitor integrator based on the dynamic amplifier further includes an external clock F _CLK for generating a clock signal to control the MOS switch Φ ₁ , the MOS switch Φ _1e , the MOS switch Φ ₂ , the MOS switch Φ _2e , the MOS switch Φ 2e , and the MOS switch Φ 2e . The clock signal provided by the switch Φ _rst and the MOS switch Φ _en is shown in FIG. 3 . The frequency of the external clock F _CLK in this embodiment is 6.144 MHz, the MOS switch Φ _1e works ahead of the MOS switch Φ ₁ , and its operating frequency is both 3.072 MHz; the MOS switch Φ _2e works ahead of the MOS switch Φ ₂ , and its working frequency is 3.072 MHz. The frequencies are both 3.072MHz, which can satisfy the oversampling rate of 64 times for the audio signal with the bandwidth of 24KHz, and the MOS switch Φ ₁ and the MOS switch Φ ₂ do not overlap. The MOS switch Φ _en works continuously after the MOS switch Φ _rst , and the total operating range of the MOS switch Φ _en and the MOS switch Φ _rst is consistent with the operating range of the MOS switch Φ ₂ or Φ _2e , which can ensure that the sampling capacitor and the integrating capacitor are turned on. A large transient voltage drop at the output node does not occur instantaneously due to charge sharing.

The switched capacitor integrator provided by the embodiment of the present disclosure has a fully differential structure, and the work of the entire switched capacitor integrator is divided into a sampling phase and a transfer amplifying phase, wherein the sampling phase is controlled by the MOS switch Φ ₁ , and the transfer amplifying phase is controlled by the MOS switch Φ ₂ Control, the two capacitors C are sampling capacitors. Compared with Φ _1e and Φ ₁ , the edge arrives earlier, which can reduce the influence of the charge injection effect on the linearity. This is a backplane sampling technology. The two sampling capacitors C and the integrating capacitors C _Inp and C _Inn form a capacitive feedback network. With the help of the high small-signal voltage gain of the dynamic amplifier, a "virtual short" effect will be formed at the input end of the dynamic amplifier, so that the sampling capacitor collects the signal in the sampling phase. The signal charge will be forced to transfer to the integrating capacitor, thus completing the integrating function.

So far, the present embodiment has been described in detail with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the dynamic amplifier-based switched capacitor integrator in the present disclosure. Embodiments of the present disclosure provide a switched capacitor integrator based on a dynamic amplifier. Compared with a traditional amplifier, the use of the dynamic amplifier can reduce the power consumption of the integrator. At the same time, the present disclosure can remove the large load capacitance of the dynamic amplifier through proper timing arrangement, and further reduce the power consumption.

The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (9)

1. A switched capacitor integrator based on a dynamic amplifier, comprising: A dynamic amplifier for amplifying an input signal, including an operational amplifier module and a tail current bias module, wherein the operational amplifier module is used to provide a predetermined amplification gain, and the tail current bias module is used for the operational amplifier module A bias current is provided to determine the DC operating point of the operational amplifier module, wherein the operational amplifier module includes four MOS field effect transistors, respectively M ₁ , M ₂ , M _C1 and M _C2 , and two MOS switch Φ _rst , the gates of M ₁ and M ₂ are respectively the reverse input terminal and the forward input terminal, the sources of M ₁ and M ₂ are connected to each other, and the drain electrodes of M ₁ and M ₂ are respectively connected to The sources of the _MC1 and _MC2 are connected, and the drains of the _MC1 and _MC2 are respectively the forward output terminal and the reverse output terminal, and are respectively connected to the reference voltage V _DD through a MOS switch Φ _rst , so Said M _C1 is connected to the gate of M _C2 ; Two switched capacitor networks, respectively set at the forward input end and the reverse input end of the dynamic amplifier, are used to sample the input signal in the first state, and input the sampled signal in the second state to the dynamic amplifier; Two integrating capacitors are respectively connected to the forward input end and the reverse output end and the reverse input end and the forward output end of the dynamic amplifier, and are used for integrating the sampled signal. 2 . The switched capacitor integrator based on dynamic amplifier according to claim 1 , wherein the operational amplifier module further comprises two bias capacitors, C _b1 and C _b2 respectively, and the C _b1 and C _b2 are connected in series, and 2 . One end of the C _b1 and C _b2 is connected to the gates of the M _C1 and M _C2 , the other end of the C _b1 is connected to the forward output terminal, and the other end of the C _b2 is connected to the reverse. Connect to the output. 3. The switched capacitor integrator based on dynamic amplifier according to claim 1, wherein the tail current bias module comprises a MOS switch Φ _en , MOS field effect transistors M _T1 , M _T2 and a resistor R _B1 , so that The gates of the _MT1 and _MT2 are connected to one end of the resistor _RB1 , the sources of the _MT1 and _MT2 are connected to the ground, and the drain of the _MT1 is connected to one end of the resistor _RB1 The other end of the resistor _RB1 is connected to a preset voltage, and the drain of the M _T2 is connected to the sources of the M ₁ and M ₂ through the MOS switch Φ _en . 4. The switched capacitor integrator based on dynamic amplifier according to claim 3, wherein each said switched capacitor network comprises a capacitor C, MOS switch Φ ₁ , MOS switch Φ _1e , MOS switch Φ ₂ and MOS switch Φ _2e , one end of the capacitor C is connected to the MOS switch Φ1, the other end is connected to the forward input terminal or the reverse input terminal of the operational amplifier module through the MOS switch _Φ2e , and _one end of the capacitor C is also connected. It is connected to the first common mode input voltage through the MOS switch Φ2, and the other end of the capacitor C is also connected to the _second common mode input voltage through the MOS switch _Φ1e . 5. The switched capacitor integrator based on dynamic amplifier according to claim 4, further comprising an external clock for generating a clock signal to control the MOS switch Φ ₁ , MOS switch Φ _1e , MOS switch Φ ₂ , MOS switch Φ _2e , MOS switch Φ _rst and MOS switch Φ _en . 6 . The switched capacitor integrator based on dynamic amplifier according to claim 5 , wherein the first state is that the MOS switch Φ _1e and the MOS switch Φ ₁ are in working state, and the second state is the MOS switch Φ 1 . The switch Φ _2e and the MOS switch Φ ₂ are in an operating state, and the second state operates after the first state. 7. The switched capacitor integrator based on dynamic amplifier according to claim 5, wherein, the MOS switch Φ _1e works ahead of the MOS switch Φ ₁ , and its operating frequency is 3.072MHz; the MOS switch Φ _2e is ahead of the MOS switch Φ 2e. MOS switch Φ ₂ works, and its operating frequency is 3.072MHz. 8. The switched capacitor integrator based on a dynamic amplifier according to claim 5, wherein the MOS switch _Φen continuously operates after the MOS switch _Φrst , and the total operation of the MOS switch _Φen and the MOS switch _Φrst The interval is consistent with the operating interval of the MOS switch Φ ₂ or Φ _2e . 9. The switched capacitor integrator based on dynamic amplifier according to claim 5, wherein the operating frequency of the external clock is 6.144MHz.

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