CN102946230B - A kind of ultra broadband single ended input difference output low noise amplifier - Google Patents

Abstract

The invention provides a low-noise amplifier with ultra-wideband single-ended input and differential output, which is characterized in that it comprises a common grid amplifier stage (1), a single-ended differential stage (2) and a capacitive cross-coupled output buffer (3), which are The output end of the gate amplification stage (1) is connected to the input end of the single-end slip stage (2), and the output end of the single-end slip stage (2) is connected to the input end of the capacitive cross-coupling output buffer (3). The pre-amplification stage and the single-end slip classification of the present invention adopt current multiplexing technology, and the current consumption of one stage can be used for two-stage amplification; the common grid amplifier stage provides broadband input matching, avoiding passive matching network; the pre-amplification stage and The load impedance of the single-end to differential stage resonates at different frequencies respectively, and the broadband signal amplification and single-end to differential functions are realized through the gain complementarity of the two stages; capacitive cross-coupling technology is added to the output buffer, and the amplitude of the output differential signal is and phase are compensated to achieve the amplitude and phase balance of the differential signal, and increase the gain of the buffer.

Description

An Ultra-Wideband Single-Ended Input Differential Output Low Noise Amplifier

technical field

The invention relates to an ultra-wideband single-end input differential output low-noise amplifier, which belongs to the technical field of radio frequency integrated circuits.

Background technique

The low noise amplifier is the key module of the receiver in the wireless transmission system. It is generally connected to the antenna to amplify the received weak signal and minimize the deterioration of the signal. Port matching, gain, noise figure, power consumption and linearity are the main technical parameters of LNAs.

The receiver generally completes the signal amplification and down conversion functions. The low noise amplifier amplifies the received RF signal, and the post-stage mixer converts the RF signal into an intermediate frequency signal. Both the local oscillator input and the RF input of the double-balanced mixer are in the form of differential pairs. The double-balanced mixer provides a high degree of isolation between LO, RF, and IF, which is the main advantage of the double-balanced mixer. . Therefore, double-balanced mixers are widely used in RF receivers. Low-noise amplifiers need to provide signals in differential form, so low-noise amplifiers often use fully differential forms. The antenna is often single-ended, and a passive balun needs to be used off-chip to convert from single-ended to differential. The use of passive balun will reduce the integration level of the system, increase the cost and area of the system, and the insertion loss of passive balun will directly deteriorate the noise figure of the receiver. However, the insertion loss of the high-frequency broadband passive balun is generally large. In order to obtain a low-cost receiver using a double-balanced mixer and maintain a low noise figure, a low-cost balun with a single-ended to differential function is required. noise amplifier.

In order to realize the function of single-ended to differential conversion, the input signal must be converted into two signals of in-phase and in-phase. There are three typical methods commonly used in the prior art to complete the single-ended-to-differential conversion function.

The first method is to use the common gate level to get the in-phase signal and use the common source level to get the anti-phase signal. This single-ended to differential circuit can be directly used in the first stage of the circuit, such as the patent application number 201010141720.1, its circuit structure is shown in Figure 1, the input low impedance of the common gate stage can provide input matching, and can Remove the noise of the common gate stage by proper parameter design. This circuit is suitable for broadband applications, but the common source amplifier and the common gate amplifier each consume one current, and only a single-stage gain is achieved with two currents.

The second method is to use a single-stage common-source stage to obtain an anti-phase signal and use two-stage common-source stages to obtain an in-phase signal. If this single-ended to differential circuit is used as the first stage, a certain matching network needs to be added to achieve input matching, such as the patent application number 201210103136.6, its circuit structure is shown in Figure 2, using the gate and source inductance For input matching, these passive components increase the area of the device, and the structure of common source amplification is not suitable for broadband applications.

The third method is to use a source-level follower to obtain the non-inverting signal and a common-source amplifier to obtain the anti-phase signal. Since this single-ended to differential circuit does not provide gain, it is often used as the last stage of the circuit. For example, the patent application number is 201210103136.6. Its circuit structure is shown in Figure 3. After cascode amplification, the active The balun converts the amplified single-ended signal into a differential signal. Since the pre-amplification stage provides a certain gain before the single-ended to differential conversion, the noise of the active balun can be suppressed. However, the source follower has broadband performance, while the common source amplifier has a narrow bandwidth, so this single-ended-to-differential conversion method is difficult to apply to broadband.

Contents of the invention

In order to solve the problems of poor gain effect, high power consumption and inability to be applied to ultra-wideband technology existing in the existing single-ended input differential output technology, the present invention further provides a low-noise ultra-wideband single-ended input differential output amplifier. For this reason, the present invention provides following technical scheme:

An ultra-wideband low-noise amplifier with single-ended input and differential output, comprising a common-gate amplifier stage (1), a single-end-to-differential conversion stage (2) and a capacitive cross-coupled output buffer (3), the output of the common-gate amplifier stage (1) The end is connected to the input end of the single-ended differential stage (2), and the output end of the single-ended differential stage (2) is connected to the input end of the capacitive cross-coupling output buffer (3).

The advantage of the present invention compared with prior art is:

1. There is a pre-amplification stage before the single-end to differential circuit of the present invention, and the pre-amplification stage and the single-end differential stage adopt current multiplexing technology to share DC current, and two-stage amplification can be performed with the current consumption of one stage;

2. The common grid amplifier stage of the present invention can provide broadband input matching, avoid complex passive matching networks, and provide a certain gain to suppress post-stage noise. The common gate amplifier stage also adds bulk resistance to the traditional common gate amplifier to reduce noise;

3. In the present invention, the load impedances of the pre-amplification stage and the single-end slip stage are respectively designed to resonate at different frequencies, and the gain of the two stages is mutually compensated to realize broadband signal amplification and single-end to differential conversion functions;

4. The circuit structure of the design of the present invention combines the single-end slip classification and the capacitive cross-coupling output buffer, and uses the capacitive cross-coupling technology to correct the balance of the amplitude and phase of the output signal in the single-end slip classification, and then Using the capacitive cross-coupled output buffer to compensate the balance of the amplitude and phase of the output differential signal again can improve the single-ended to differential performance.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings without making creative efforts.

Fig. 1 is the circuit structural representation that obtains in-phase signal with common-source stage and obtains anti-phase signal by adopting common gate stage in the prior art;

Fig. 2 is the schematic diagram of the circuit structure of obtaining the in-phase signal by using a single-stage common-source stage to obtain an in-phase signal with two-stage common-source stages in the prior art;

Fig. 3 is the schematic diagram of the circuit structure obtained by using a source follower to obtain an in-phase signal with a common-source amplifier to obtain an inversion signal in the prior art;

FIG. 4 is a schematic diagram of a circuit structure of an ultra-wideband single-ended input differential output low noise amplifier provided by a specific embodiment of the present invention.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The specific embodiment of the present invention provides an ultra-wideband single-ended input differential output low-noise amplifier, as shown in Figure 1, including a common grid amplifier stage (1), a single-ended conversion stage (2) and a capacitive cross-coupled output buffer device (3), the output end of the common grid amplifier stage (1) is connected to the input end of the single-end slip stage (2), and the output end of the single-end slip stage (2) is connected to the capacitor cross-coupled output buffer (3) input connection.

Specifically, the common-gate amplifier stage (1) can use a common-gate amplifier M1, and the added resistor R1 can reduce noise. The source of the common-gate amplifier M1 is grounded with an inductor L1 to provide source bias. The drain of the common-gate amplifier M1 Using the inductor L2 as the load, the low impedance of the source input can provide broadband input matching;

The single-ended to differential stage (2) adopts a common source amplifier M2 to obtain an inverting output, and uses a two-stage common source amplifier M2 and M3 to obtain a non-inverting output; the source stages of the two-stage common source amplifiers M2 and M3 are grounded through a capacitor C3 as AC ground, so that M2 and M3 can realize the function of the common source amplifier, the inverting output of the two-stage common source amplifier M2 and M3 is connected to the gate of the NMOS transistor M5 through the capacitor C4, and the non-inverting output of the two-stage common source amplifier M2 and M3 The capacitor C5 is coupled to the gate of the NMOS transistor M4, and the drains of the NMOS transistors M4 and M5 are loaded with inductors L3 and L4 to obtain differential signals Vout- and Vout+. Capacitive cross-coupling technology can correct the amplitude of the output differential signal and phase balance;

The capacitive cross-coupling output buffer (3) is used to connect the non-inverting signal Vout+ to the gate of the NMOS transistor M7, couple to the gate of the NMOS transistor M8 through the capacitor C7, and connect the inverting signal Vout- to the NMOS transistor The gate of M6 is coupled to the gate of NMOS transistor M9 through capacitor C6. Capacitive cross-coupling output buffer (3) by changing the NMOS current source in the traditional source follower to a radio frequency NMOS tube amplifier, using capacitive cross-coupling technology, the gain of the buffer is increased, and the amplitude and phase of the output differential signal Compensation can improve the balance performance of the amplitude and phase of the differential signal.

Preferably, the output of the common-gate amplifier stage (1) is capacitively coupled to the single-end slip stage (2), and the common-gate amplifier stage (1) and the single-end slip stage (2) share a direct current through a current multiplexing technique, Therefore, the power consumption can be reduced, and the two-stage amplification is carried out under the same current consumption, and the gain is increased at the same time.

Preferably, the load impedances of the common-gate amplifier stage (1) and the single-ended slip stage (2) resonate at different frequencies respectively, the common-gate amplifier stage (1) can provide high gain at low frequencies, and the single-end slip stage (2) provides high gain at high frequencies; the common grid amplifier stage (1) and the single-ended slip stage (2) provide high gain within a wide band by cascading.

Preferably, the single-ended differential stage (2) and the capacitive cross-coupling output buffer (3) are combined, and the amplitude and phase balance of the output differential signal are corrected by capacitive cross-coupling technology in the single-ended differential stage (2) , and compensate the amplitude and phase balance of the output differential signal again through the capacitive cross-coupling output buffer (3), so as to improve the single-ended to differential performance. The circuit improvement provided by the technical solution does not increase the current consumption, and only by adding some capacitors, a higher buffer stage gain and better amplitude and phase balance performance of the differential signal are obtained.

Taking the 0.13um CMOS technology as an example, the transistors are all MOS tubes, the power supply voltage is 1.3V, the main circuit consumes 3.5mA of current, and the buffer consumes 2mA of current. The circuit simulation results of the specific implementation example of the present invention are shown in the following table:

indicators value unit bandwidth >2 GHz power consumption 9 mW S11 <-10 dB Noise Figure <3 dB power gain >20 dB Amplitude balance error <0.1 dB Phase balance error <0.1 Degree

By adopting the technical solution provided in this specific embodiment, the following technical effects can be achieved:

1. There is a pre-amplification stage before the single-end to differential circuit of the present invention, and the pre-amplification stage and the single-end differential stage adopt current multiplexing technology to share DC current, and two-stage amplification can be performed with the current consumption of one stage;

2. The common grid amplifier stage of the present invention can provide broadband input matching, avoid complex passive matching networks, and provide a certain gain to suppress post-stage noise. The common gate amplifier stage also adds bulk resistance to the traditional common gate amplifier to reduce noise;

3. In the present invention, the load impedances of the pre-amplification stage and the single-end slip stage are respectively designed to resonate at different frequencies, and the gain of the two stages is mutually compensated to realize broadband signal amplification and single-end to differential conversion functions;

4. The circuit structure of the design of the present invention combines the single-end slip classification and the capacitive cross-coupling output buffer, and uses the capacitive cross-coupling technology to correct the balance of the amplitude and phase of the output signal in the single-end slip classification, and then Using the capacitive cross-coupled output buffer to compensate the balance of the amplitude and phase of the output differential signal again can improve the single-ended to differential performance.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technical field can easily think of Changes or substitutions should fall within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (4)

1. a ultra broadband single ended input difference output low noise amplifier, it is characterized in that, comprise common grid amplifying stage (1), single-ended transfer difference level (2) and capacitive cross coupling output buffer (3), the output of grid amplifying stage (1) is connected with the input of single-ended transfer difference level (2) altogether, and the output of single-ended transfer difference level (2) is connected with the input of capacitive cross coupling output buffer (3);

Wherein, grid amplifying stage (1) adopts cathode-input amplifier M1 altogether, and the source electrode of cathode-input amplifier M1 adopts inductance L 1 ground connection to provide source-biased, and the drain electrode of cathode-input amplifier M1 adopts inductance L 2 as load;

Single-ended transfer difference level (2) adopts one-level common-source amplifier M2 to obtain anti-phase output, and adopts two-stage common-source amplifier M2 and M3 to obtain homophase output; The source electrode of two-stage common-source amplifier M2 and M3 is by electric capacity C3 ground connection, the grid of NMOS tube M5 is received in the anti-phase output of two-stage common-source amplifier M2 and M3 by electric capacity C4, the homophase of two-stage common-source amplifier M2 and M3 exports the grid being received NMOS tube M4 by electric capacity C5 coupling, in the drain electrode of NMOS tube M4 and M5 with inductance L3 and L4 as load, obtain differential signal Vout-and Vout+;

Capacitive cross coupling output buffer (3) is for receiving the grid of NMOS tube M7 by in-phase signal Vout+, and the grid of NMOS tube M8 is received by electric capacity C7 coupling, and inversion signal Vout-is received the grid of NMOS tube M6, and receive the grid of NMOS tube M9 by electric capacity C6 coupling.

2. ultra broadband single ended input difference output low noise amplifier according to claim 1, it is characterized in that, the output of grid amplifying stage (1) is capacitively coupled to single-ended transfer difference level (2) altogether, and grid amplifying stage (1) and single-ended transfer difference level (2) are by current multiplexing technology common DC electric current altogether.

3. ultra broadband single ended input difference output low noise amplifier according to claim 1, it is characterized in that, resonance is in different frequencies respectively for the load impedance of grid amplifying stage (1) and single-ended transfer difference level (2) altogether, and grid amplifying stage (1) and single-ended transfer difference level (2) are associated in broadband by level and provide high-gain altogether.

4. ultra broadband single ended input difference output low noise amplifier according to claim 1, it is characterized in that, single-ended transfer difference level (2) and capacitive cross coupling output buffer (3) are combined, in single-ended transfer difference level (2), correct the amplitude of output difference sub-signal and the balance of phase place with electric capacity cross-coupling technique, and again the amplitude of output difference sub-signal and the balance of phase place are compensated by capacitive cross coupling output buffer (3).