CN104779917B - A kind of receiver front end circuit based on integrated inductor noise cancellation technology - Google Patents

Abstract

The invention relates to a receiver front-end circuit based on integrated inductive noise cancellation technology, which belongs to the field of radio frequency and millimeter wave integrated circuit design. It is composed of a frequency converter and a transimpedance amplifier; wherein, the input signal is divided into two paths and connected to the input ends of the low noise amplifiers of the two branches respectively, and the output terminals of the low noise amplifiers of each branch are connected to the I path and the Q path of the branch path The common input terminal of the mixer; the local oscillator terminals of the I-way mixer in the two branches are respectively connected with the I-way local oscillator input terminals of the whole circuit; the local oscillator terminals of the Q-way mixer in the two branches are respectively It is connected with the Q-channel local oscillator input of the whole circuit; the differential output terminal of the I-channel mixer in one branch is connected with the differential output terminal of the Q-channel mixer in the other branch, and is connected with the transimpedance in the branch The differential inputs of the amplifiers are connected. The invention can greatly eliminate the thermal noise generated by the integrated inductance.

Description

A Receiver Front-End Circuit Based on Integrated Inductive Noise Cancellation Technology

technical field

The invention belongs to the field of radio frequency and millimeter wave integrated circuit design, in particular to the design of a front-end circuit of a receiver with high performance and low noise figure (Noise Figure: NF).

Background technique

With the development of CMOS (Complementary Metal-Oxide-Semiconductor: Complementary Metal-Oxide-Semiconductor) high-speed wireless communication circuits and systems, and the continuous improvement of user requirements for communication quality and speed experience, the rate of information exchange continues to increase, especially Indoor high-speed communication needs are becoming more and more important. According to Mason's prediction, by 2016, 80% of the global wireless communication data volume will be generated indoors. In this context, the wireless local area network (WLAN) technology is advancing by leaps and bounds, among which the IEEE 802.11 series standards are the most representative. At present, this standard has been developed to the fifth generation 802.11ac, and the communication data rate will reach Gbps ( Giga-bit-per-second) and above, thus attracting widespread attention from academia and industry.

Specific to the wireless receiver system working in the radio frequency band, it is necessary to achieve high gain and low noise while meeting low cost and low power consumption, so as to realize the loss and noise figure of the receiver front-end system at high frequencies. With the development of wireless local area network technology, the data transmission rate continues to increase, the modulated vector constellation diagram (Constellation diagram) becomes more and more dense, and the noise figure of the receiver is also higher and higher. In order to reduce the number of off-chip components and reduce costs, a large number of integrated inductors will be used in the circuit. However, due to the low quality factor (Quality Factor), the integrated inductor contains large parasitic resistance, which will generate a large amount of thermal noise and seriously affect the noise performance of the receiver front-end circuit.

At present, there are mainly two types of inductors traditionally used in receiver front-end circuits. One is to use off-chip inductors and use their high quality factor to reduce noise. For example, the reference "Yuan-Hung Chung, etc., "A 4-in-1 (WiFi/BT/FM/GPS) connectivity SoC with enhanced co-existence performance in 65nm CMOS," IEEE ISSCC Dig.Tech.Papers, pp. 172,174,19-23 Feb.2012" and "MingHe,etc.,"20.5 A 40nm dual-band 3-stream 802.11a/b/g/n/ac MIMO WLAN SoC with1.1Gb/s over-the-air throughput , "IEEE ISSCC Dig. Tech. Papers, pp. 350, 351, 9-13 Feb. 2014". This approach increases the cost of circuit manufacturing and affects the degree of integration; the other is to use common on-chip integrated inductors, such as the reference "SanghoonJoo, Tae-Young Choi, and Byunghoo Jung, "A 2.4-GHzResistive Feedback LNA in 0.13-μm CMOS,"IEEE J.Solid-State Circuits,vol.44,no.11,pp.3019-3029,Nov.2009". This scheme inevitably introduces high thermal noise.

Therefore, it is necessary to invent a new circuit structure to properly resolve the contradiction between circuit design cost and noise performance, while satisfying the integration and performance of the receiver front-end system.

Contents of the invention

In view of this, the object of the present invention is to propose a receiver front-end based on integrated inductance noise cancellation technology, on the basis of using integrated inductance, through a new circuit structure, eliminate the noise contributed by the inductance, and ensure the low noise of the entire receiver. The noise figure meets the performance requirements of the wireless communication standard for the receiver front-end, and improves the integration of the entire receiver front-end system.

In order to achieve the above object, a kind of receiver front-end circuit based on integrated inductive noise cancellation technology of the present invention is characterized in that, the circuit includes two identical branches, the first branch is routed by the first low-noise amplifier, the first I-way It is composed of a Q-way mixer and a first transimpedance amplifier, and the second branch is composed of a second low-noise amplifier, a second I-way and Q-way mixer, and a second transimpedance amplifier; wherein, the input signal is divided into two The road is respectively connected with the input end of the low noise amplifier of the first branch and the low noise amplifier of the second branch, and the output terminal of the low noise amplifier of the first branch is connected with the I road and the Q road mixer of the first branch The common input terminal of the second branch; the output terminal of the low noise amplifier of the second branch is connected to the common input of the I road and the Q road mixer of the second branch; the local oscillator terminal of the I road mixer of the first branch and the first branch The local oscillator end of the two-branch I road mixer is connected with the I road local oscillator input end of the whole circuit respectively; The Q-way local oscillator input is connected; the differential output of the I-way mixer in the first branch is connected with the differential output of the Q-way mixer in the second branch, and is connected with the transimpedance amplifier in the first branch The differential input terminals of the first branch are connected to each other; the differential output terminal of the transimpedance amplifier in the first branch is the differential output terminal of the I road of the whole receiver front end; The differential output terminal of the Q-way mixer is connected, and is connected with the differential input terminal of the transimpedance amplifier in the second branch, and the differential output terminal of the transimpedance amplifier in the second branch is the Q-channel differential output of the entire receiver front end end.

The first low-noise amplifier in the first branch can be composed of gate inductance L _g , nMOS transistor M ₁ , inductance L _s and inductance L _d ; wherein, one end of gate inductance L _g is connected to the input end, and the other end is connected to nMOS The gate terminal of the tube M ₁ , the source of the nMOS tube M ₁ is connected to one end of the inductor L _s , and the other end of the inductor L _s is grounded to GND; the drain of M ₁ is connected to the output terminal and one end of the inductor L _d , and the other end of the L _d is connected to Power supply VDD.

The second low noise amplifier in the second branch can be composed of nMOS transistor M _2n and pMOS transistor M _2p ; wherein, the gate terminals of nMOS transistor M _2n and pMOS transistor M _2p are connected together and connected to the input end, and the nMOS transistor M 2p The source of the M _2n is grounded to GND, the source of the pMOS transistor M _2p is connected to the power supply VDD, and the drains of the nMOS transistor M _2n and the pMOS transistor M _2p are connected together and connected to the output terminal.

The mixers in the first branch and the second branch are the same, and both of them can include two mixers of I channel and Q channel. Technical characteristics and beneficial effects of the present invention:

Aiming at the problem of excessive thermal noise of the integrated inductance, the present invention adopts a new circuit structure, introduces noise cancellation technology, eliminates the noise contributed by the integrated inductance, realizes improved noise performance, and solves the problem of integrated inductance and noise in the receiver system The contradiction that performance cannot be solved at the same time achieves low noise and high integration on chip at the same time, effectively avoiding the trade-off between noise and integration in traditional design methods, improving the performance of the entire receiver front-end system and ensuring reliable circuit design performance and electrostatic robustness.

Description of drawings

Fig. 1 is the circuit diagram of the receiver front end based on integrated inductive noise cancellation technology proposed by the present invention;

Fig. 2 is the working principle diagram of the receiver front end (I road) based on integrated inductive noise cancellation technology in the embodiment of the present invention;

Fig. 3 is the simulation result of the noise figure of the output frequency range of 1MHz-100MHz with the input signal frequency range of 5.001GHz-5.1GHz, the mixer local oscillator frequency of 5GHz, and the receiver front-end circuit as an embodiment of the present invention.

Fig. 4 is the noise analysis of the present invention with the input signal frequency being 5.01 GHz, the local oscillator frequency of the mixer being 5 GHz, and the output frequency of the receiver front-end circuit embodiment being 10 MHz, that is, the noise power contributed by the gate inductance accounts for 1% of the branch circuit The proportion of noise power contributed;

Fig. 5 is the noise analysis of the present invention that the frequency of the input signal is 5.01GHz, the local oscillator frequency of the mixer is 5GHz, and the output frequency of the receiver front-end circuit embodiment is 10MHz, that is, the noise power contributed by the grid inductance accounts for the noise power of the whole circuit proportion.

detailed description

In order to make the object, technical solution and features of the present invention clearer, specific implementation methods will be described in detail below in conjunction with the accompanying drawings.

The present invention proposes a receiver front-end circuit based on integrated inductance noise cancellation technology. On the basis of using integrated inductance, a new circuit structure is adopted to eliminate thermal noise contributed by integrated inductance in a feedforward manner, ensuring low The noise figure meets the performance requirements of the wireless communication standard for the receiver front-end, and improves the integration of the entire receiver front-end system.

In order to achieve the above purpose, a receiver front-end circuit based on integrated inductive noise cancellation technology of the present invention adopts a zero-IF architecture, and the entire receiver front-end circuit is divided into two identical branches, as shown in Figure 1, including: The first branch is composed of low noise amplifier 1, I-way and Q-way mixer 1, and transimpedance amplifier 1, and the second branch is composed of low-noise amplifier 2, I-way and Q-way mixer 2, and transimpedance amplifier 2;

Among them, the input signal is divided into two paths and connected to the input terminals of the low noise amplifiers 1 and 2 of the branches 1 and 2 respectively, and the output terminal of the low noise amplifier 1 of the branch 1 is connected to the I and Q paths of the branch 1 for mixing The common input end of device 1; The input end connects the input end of low-noise amplifier 2 in branch 2, and the output end of low-noise amplifier 2 connects the common input end of I road and Q road mixer in branch 2; The local oscillator ends of the I-way mixer in 1 and branch 2 are connected with the I-way local oscillator input of the whole circuit respectively, and the local oscillator terminals of the Q-way mixer in the branch 1 and branch 2 are respectively connected with the whole circuit The Q-way local oscillator input of the branch is connected; the differential output of the I-way mixer in the branch 1 is connected with the differential output of the Q-way mixer in the branch 2, and is connected with the transimpedance amplifier 1 in the branch 1 The differential input ends are connected, and the differential output end of the transimpedance amplifier 1 in branch 1 is the I-way differential output end of the front end of the entire receiver; the differential output end of the I-way mixer in branch 2 is mixed with the Q-way mixer in branch 1 The differential output terminal of the frequency converter is connected, and is connected with the differential input terminal of the transimpedance amplifier 2 in the branch circuit 2, and the differential output terminal of the transimpedance amplifier 2 in the branch circuit 2 is the Q channel differential output terminal of the entire receiver front end.

The low-noise amplifier 1 in the above-mentioned branch 1, its specific circuit structure is shown in Figure 1, which is composed of a gate inductance L _g , an nMOS transistor M ₁ , an inductance L _s and an inductance L _d ; where one end of the gate inductance L _g is connected to The input terminal, the other end is connected to the gate terminal _of the nMOS transistor M1, the source of the nMOS transistor M1 is connected to _one end of the inductor L _s , and the other end of the inductor L _s is grounded to GND; the drain of M1 is connected to the output terminal and _one end of the inductor L _d , the other end of L _d is connected to the power supply VDD.

The low-noise amplifier 2 in branch 2 has a specific circuit structure as shown in Figure 1, and is composed of nMOS transistor M _2n and pMOS transistor M _2p ; wherein, the gate terminals of nMOS transistor M _2n and pMOS transistor M _2p are connected together and Connected to the input terminal, the source of the nMOS transistor M _2n is grounded to GND, the source of the pMOS transistor M _2p is connected to the power supply VDD, the drains of the nMOS transistor M _2n and the pMOS transistor M _2p are connected together and connected to the output terminal.

The working principle of each component of this circuit is described as follows:

The thermal noise of an integrated inductor can be equivalent to a series connection of an ideal inductor and a noise voltage source, taking the I output as an example, as shown in Figure 2. The low noise amplifier of branch 1 is a traditional source degenerate structure, and its input terminal is a series resonant network, therefore, the voltage applied between the gate terminal and the source terminal of the nMOS transistor is V _gs , ideally 90°; and The noise generated by the gate inductance, due to the different positions of the noise source, the noise phase of the gate terminal and the source terminal, ideally -90°. The low-noise amplifier of branch 2 is an independent inverter structure, and the input signal will not have a 90° phase shift after inversion; for noise, there will also be no 90° phase shift. After the signal and noise in branch 1 and branch 2 reach the output terminals of low noise amplifier 1 and low noise amplifier 2 respectively, their phases are reversed. In an ideal situation, the phases of the signal and noise of branch 1 are -90° and 90° respectively; the phases of the signal and noise of branch 2 are both 180°.

The mixers in the branch 1 and the branch 2 are the same, both of which include two mixers of the I channel and the Q channel, and a total of 4 identical conventional mixers are used. The signal and noise output by the two low noise amplifiers 1 and 2 are respectively received and output in the form of current, as shown in FIG. 2 . The LO input end of the I-way mixer in branch 1 is the I-way LO, and the LO input end of the Q-way mixer in branch 2 is the Q-way LO. Therefore, after down-conversion, the phases of the signal and noise in branch 1 are still -90° and 90°, respectively, while the phases of the signal and noise in branch 2 are both -90° after frequency mixing and phase shifting. The signals and noises of branch 1 and branch 2 are summed in current mode at the input of the transimpedance amplifier and merged into one path. The current is converted into a voltage through the transimpedance amplifier shown in Figure 1, and an I output is finally generated. From the relationship between the phases of the signal and noise, it can be seen that the signal is superimposed in an in-phase manner, while the noise is canceled in an anti-phase manner. The situation and specific description of the Q-channel output can be obtained in a manner similar to that of the I-channel output. The difference is that the Q-channel mixer is in the branch 1, and the I-channel mixer is in the branch 2. The specific implementation manner of the low noise amplifier 1 and the low noise amplifier 2 is the same as that of the I output.

The transimpedance amplifier 1 and the transimpedance amplifier 2 are exactly the same, and both are realized by conventional fully differential transimpedance amplifiers in the embodiment.

In order to verify the correctness and effectiveness of the receiver front-end based on the integrated inductive noise cancellation technology proposed by the present invention, a 65nm CMOS process is used to carry out circuit simulation verification for the wireless receiver front-end circuit embodiment working in the 5GHz radio frequency band, and its circuit principle The figure is shown in Figure 1, where the radio frequency signal is amplified by the low noise amplifier and converted to the baseband by means of zero intermediate frequency. The local oscillator signals of the I and Q channels of the mixer are provided off-chip and converted by the on-chip balun It is a differential signal, connected to the local oscillator input of the mixer, the baseband current signal is converted into a voltage signal by a transimpedance amplifier, and the 0.1dB bandwidth of the useful signal is about 100MHz. The parameters and indicators in Figure 2 are listed in the table below:

Among them, the inductance value of the component L _s is small, and it can be replaced by a wire in an actual circuit.

The rest of the circuits, such as mixers and transimpedance amplifiers, are implemented using standard circuit structures.

The present invention simulates and analyzes the noise factor of the key index of the front-end circuit of the receiver, and the curves of the result changing with the frequency are shown in Fig. 3, Fig. 4 and Fig. 5 respectively. In Figure 3, the solid circle represents the relationship between the noise figure of the single branch 1 and the frequency, the solid triangle represents the relationship between the noise figure of the single branch 2 and the frequency, and the solid square represents the relationship between the overall noise figure and the frequency when the two branches work at the same time. The shaded part in Figure 4 represents the ratio of the noise power contributed by the grid inductance to the noise power of branch 1 after analyzing the noise figure of branch 1 alone at an output frequency of 10 MHz. The shaded part in Figure 5 represents the ratio of the noise power contributed by the gate inductance to the total noise power when the output frequency is 10MHz after analyzing the overall noise figure of the two branches connected in parallel.

From the results, the embodiment of the receiver front-end based on the integrated inductive noise cancellation technology proposed by the present invention has achieved a minimum noise figure of 1.53dB when operating at a frequency of 5 GHz, and the noise figure is improved compared to branch 1 working alone. 1dB, and by adopting the noise cancellation technology proposed by the present invention, in this embodiment, the contribution of the gate inductance noise to the noise of the entire circuit is reduced from 68% to 31%. Compared with the conventional technology, this embodiment eliminates the thermal noise of the integrated gate inductance while contributing to the signal gain by introducing the branch circuit 2 . On the premise of not affecting the linearity index and not obviously increasing the power consumption, it achieves good noise performance.

In a word, the above description is only a verification example of the front end of the wireless receiver under the specific CMOS technology and the specific 5GHz radio frequency band of the present invention, and is not intended to limit the protection scope of the present invention.

Claims (4)

1. A receiver front-end circuit based on integrated inductive noise cancellation technology, it is characterized in that the circuit comprises two identical branches, the first branch is mixed by the first low noise amplifier, the first I road and Q road device, the first transimpedance amplifier, the second branch is composed of the second low-noise amplifier, the second I-way and Q-way mixer, and the second transimpedance amplifier; wherein, the input signal is divided into two paths and the first branch respectively The low-noise amplifier of the first branch is connected to the input end of the low-noise amplifier of the second branch, and the output terminal of the low-noise amplifier of the first branch is connected to the common input of the mixer of the I road and the Q road of the first branch; The output terminal of the low-noise amplifier of the two branches is connected to the common input of the I road and the Q road mixer of the second branch; The local oscillator end of the frequency converter is connected with the I road local oscillator input end of the whole circuit respectively; Connected; the differential output end of the I road mixer in the first branch is connected with the differential output end of the Q road mixer in the second branch, and is connected with the differential input end of the transimpedance amplifier in the first branch; The differential output end of the transimpedance amplifier in the first branch is the I road differential output end of the whole receiver front end; the differential output end of the I road mixer in the second branch and the Q road mixer in the first branch The differential output terminal is connected to the differential input terminal of the transimpedance amplifier in the second branch, and the differential output terminal of the transimpedance amplifier in the second branch is the Q-channel differential output terminal of the entire receiver front end. 2. The front-end circuit according to claim 1, wherein the first low-noise amplifier in the first branch is composed of a gate inductance _Lg , an _nMOS transistor M1, _an inductance _Ls and an inductance Ld; wherein , one end of the gate inductance L _g is connected to the input end, the other end is connected to the gate end of the nMOS transistor M1, the source _of the nMOS transistor M1 is connected to _one end of the inductor L _s , the other end of the inductor L _s is grounded to GND; the drain _of the M1 is connected to The output end and one end of the inductor L _d , and the other end of the L _d is connected to the power supply VDD. 3. front-end circuit as claimed in claim 1, is characterized in that, the second low-noise amplifier in the described second branch is made up of nMOS transistor M _2n , pMOS transistor M _2p ; Wherein, nMOS transistor M _2n and pMOS transistor The gate terminals of M _2p are connected together and connected to the input terminal, the source of the nMOS transistor M _2n is grounded to GND, the source of the pMOS transistor M _2p is connected to the power supply VDD, the drain terminals of the nMOS transistor M _2n and pMOS transistor M _2p are connected together and connected to the output end. 4. The front-end circuit according to claim 1, 2 or 3, characterized in that, the mixers in the first branch and the second branch are the same, and both include two mixers of I-way and Q-way.