WO2016145950A1

WO2016145950A1 - Single-ended input and double-balanced passive mixer

Info

Publication number: WO2016145950A1
Application number: PCT/CN2016/072686
Authority: WO
Inventors: 陈超; 吴建辉; 李红
Original assignee: 东南大学
Priority date: 2015-03-18
Filing date: 2016-01-29
Publication date: 2016-09-22
Also published as: CN104702219A; CN104702219B

Abstract

A single-ended input and double-balanced passive mixer comprises a Balun transconductance stage, a passive local oscillator switch and a trans-impedance amplifier; the Balun transconductance stage is a transconductance stage circuit outputting double-channel differential current by using single-channel bias current; the output impedance of the transconductance stage is lowered at the local oscillator frequency and a similar AC virtual earth is constructed by the transconductance stage by utilizing the impedance transfer effect of the passive local oscillator switch; when input voltage is changed, transconductance transistors respectively pull current from differential outputs, and a function of outputting the double-channel differential current by using the single-channel bias current is realized. The single-ended input and double-balanced passive mixer saves half of transconductance stage current, is a passive mixer with the same equivalent transconductance and significantly reduced power consumption, and is suitable for single-ended input and differential output.

Description

Single-ended input double balanced passive mixer

Technical field

The invention relates to a low power single-ended input double balanced passive mixer, belonging to the technical field of mixers.

Background technique

In the RF receiving system, the mixer is responsible for frequency conversion of the RF signal to the baseband or intermediate frequency band. It is the core module in the receiving link. As a link between the RF signal and the IF signal, the power consumption level occupies the receiving link. A considerable share. Therefore, in order to achieve low power consumption of the overall receiving circuit, the optimization design of the mixer power consumption is critical. From the structure of the RF front-end, in many cases, in order to directly couple with the antenna, the low-noise amplifier of the RF front-end adopts a single-ended input and a single-ended output structure. The mixer should use a differential double-balanced structure from the perspective of performance and port isolation. In this case, a double-balanced mixer with a single-ended input is needed to match the low noise amplifier. The more common way is to connect the conventional fully differential mixer to the pseudo differential mode. However, from the power level, the pseudo differential method wastes the bias current of one of the transconductance branches, which affects the efficiency.

Summary of the invention

OBJECT OF THE INVENTION: To overcome the deficiencies in the prior art, the present invention provides a single-ended input double-balanced passive mixer that saves half of the transconductance current, achieving the same equivalent transconductance and significantly reducing Power consumption, suitable for single-ended input, passive mixers for differential output applications.

Technical Solution: To achieve the above object, the technical solution adopted by the present invention is: a single-ended input double-balanced passive mixer, including a balun transconductance stage, a passive local oscillator switch, and a transimpedance amplifier; The level is responsible for converting the input RF voltage into RF current; the passive local oscillator switch frequency-converts the RF current; the transimpedance amplifier is responsible for converting the intermediate frequency current into an output intermediate frequency voltage, and the balun transconductance stage adopts a single bias Current realizes a trans-conductor circuit with two differential current outputs. The transconductance stage utilizes the impedance shifting action of the passive local oscillator switch to pull the transconductance output impedance at the local oscillator frequency and construct a similar AC virtual ground; when the input voltage When changing, the current is drawn from the differential output terminal across the conduit to achieve a single differential current to achieve dual differential current output.

The balun transconductance stage includes a first transconductance amplifier (A1), first, second, third NMOS transistors, a first PMOS transistor, an input voltage connected to a gate of the third NMOS transistor (MN3), and a third NMOS The source of the tube (MN3) is connected to the drain of the second NMOS transistor (MN2); the source of the second NMOS transistor (MN2) is grounded, and the gate is connected to the gate of the first NMOS transistor (MN1); the first NMOS transistor The source of (MN1) is grounded, and the gate and the drain are connected to the negative terminal of the reference current source. The positive terminal of the reference current source is connected to the power supply; the drain of the third NMOS transistor (MN3) is connected to the first PMOS transistor (MP1). Drain, first PMOS The source of the transistor (MP1) is connected to the power supply, and the gate is connected to the output of the first transconductance amplifier (A1); the negative input terminal of the first transconductance amplifier (A1) is connected to the reference voltage, and the positive input terminal is connected to the first resistor. The positive terminal of (R1), the negative terminal of the first resistor (R1) is connected to the drain of the first PMOS transistor (MP1); the positive terminal of the second resistor (R2) is connected to the positive input terminal of the first transconductance amplifier (A1). Connected, the negative terminal of the second resistor (R2) is connected to the gate of the third NMOS transistor (MN3).

The passive local oscillator switch includes first and second capacitors; a positive terminal of the first capacitor (C1) is connected to a drain of the third NMOS transistor (MN3), and a negative terminal is connected to a second PMOS transistor (MP2) a source and a source of the third PMOS transistor (MP3); a positive terminal of the second capacitor (C2) connected to a source of the third NMOS transistor (MN3), and a negative terminal connected to a source of the fourth PMOS transistor (MP4) The source of the fifth PMOS transistor (MP5).

The transimpedance amplifier includes a second transconductance amplifier (A2), and a drain of the second PMOS transistor (MP2) and a drain of the fourth PMOS transistor (MP4) are connected to a negative input of the second transconductance amplifier (A2) The drain of the third PMOS transistor (MP3) and the drain of the fifth PMOS transistor (MP5) are connected to the positive input terminal of the second transconductance amplifier (A2); the second transconductance amplifier (A2) and the fifth PMOS transistor The gate of (MP5) is connected to the negative pole of the local oscillator signal, the gates of the third PMOS transistor (MP3) and the fourth PMOS transistor (MP4) are connected to the positive pole of the local oscillator signal; and the positive terminal of the third resistor (R3) and the third capacitor ( The positive terminal of C3) is connected to the positive input terminal of the second transconductance amplifier (A2), and the negative terminal of the third resistor (R3) and the negative terminal of the third capacitor (C3) are connected to the negative output of the second transconductance amplifier (A2). The positive terminal of the fourth resistor (R4) and the positive terminal of the fourth capacitor (C4) are connected to the negative input terminal of the second transconductance amplifier (A2), and the negative terminal of the fourth resistor (R4) and the fourth capacitor (C4) The negative terminal of the second transconductance amplifier (A2) is terminated.

Advantageous Effects: The single-ended input double-balanced passive mixer provided by the present invention has the following effects compared with the prior art:

Since the balun transconductance stage uses a single bias current to realize a dual differential current output transconductance stage circuit, the transconductance stage utilizes the impedance shifting action of the passive local oscillator switch to pull the transconductance at the local oscillation frequency. The output impedance of the stage is similar to that of the AC virtual ground; when the input voltage changes, the current is drawn from the differential output terminal across the conduit to realize the function of dual differential current output by a single bias current. The PMOS current source and the NMOS current source are respectively connected in series, and the impedance variation of the passive mixing switch is utilized to pull the output impedance of the transconductance stage at the local oscillator frequency and construct an approximate AC virtual ground, and the change of the input voltage will cause the cross-catheter. The current changes, and since the current flowing into the power supply and ground across the transconductance stage is fixed, and the impedance of the source-drain across the conduit to the local oscillator switch is sufficiently low, the RF current generated is injected into the local oscillator switching stage. The source and drain currents are equal in magnitude and opposite in phase. The bias current can be reduced by half compared to conventional differential structures with the same transconductance value.

It can be seen from the above that the present invention is applicable to passive mixers for single-ended input and differential output applications. The mixer The use of a single bias current achieves the effect of dual differential current outputs, saving half of the transconductance current and achieving the same equivalent transconductance, significantly reducing power consumption.

DRAWINGS

1 is a circuit diagram of a low power single-ended input double balanced passive mixer of the present invention;

2 is a graph showing a conversion gain of a low-power single-ended input double-balanced passive mixer with an input frequency according to the present invention;

detailed description

The present invention will be further described below in conjunction with the accompanying drawings.

A single-ended input double-balanced passive mixer, as shown in FIG. 1 , the mixer is composed of a balun transconductance stage, a local oscillator switch, and a transimpedance amplifier; and is divided from a functional module and a conventional passive hybrid. The frequency is consistent: the transconductance stage is responsible for converting the input RF voltage into RF current; the passive local oscillator switch frequency-converts the RF current; and the transimpedance amplifier is responsible for converting the intermediate frequency current into the output intermediate frequency voltage. The balun transconductance stage uses a single bias current to realize a dual differential current output transconductance stage circuit, and the transconductance stage utilizes the impedance shifting action of the passive local oscillator switch to pull the transconductance stage at the local oscillation frequency The output impedance is constructed similar to the AC virtual ground; when the input voltage changes, the current is drawn from the differential output terminal across the conduit to achieve a single differential current to achieve dual differential current output.

The balun transconductance stage includes a first transconductance amplifier (A1), first, second, third NMOS transistors, a first PMOS transistor, an input voltage connected to a gate of the third NMOS transistor (MN3), and a third NMOS The source of the tube (MN3) is connected to the drain of the second NMOS transistor (MN2); the source of the second NMOS transistor (MN2) is grounded, and the gate is connected to the gate of the first NMOS transistor (MN1); the first NMOS transistor The source of (MN1) is grounded, and the gate and the drain are connected to the negative terminal of the reference current source. The positive terminal of the reference current source is connected to the power supply; the drain of the third NMOS transistor (MN3) is connected to the first PMOS transistor (MP1). The drain, the source of the first PMOS transistor (MP1) is connected to the power supply, and the gate is connected to the output terminal of the first transconductance amplifier (A1); the negative input terminal of the first transconductance amplifier (A1) is connected to the reference voltage, and The input terminal is connected to the positive terminal of the first resistor (R1), the negative terminal of the first resistor (R1) is connected to the drain of the first PMOS transistor (MP1), and the positive terminal of the second resistor (R2) is connected to the first transconductance amplifier ( The positive input terminal of A1) is connected, and the negative terminal of the second resistor (R2) is connected to the gate of the third NMOS transistor (MN3).

The transimpedance amplifier includes a second transconductance amplifier (A2), and a drain of the second PMOS transistor (MP2) and a drain of the fourth PMOS transistor (MP4) are connected to a negative input of the second transconductance amplifier (A2) End, third PMOS tube (MP3) The drain and the drain of the fifth PMOS transistor (MP5) are connected to the positive input terminal of the second transconductance amplifier (A2); the gates of the second transconductance amplifier (A2) and the fifth PMOS transistor (MP5) are connected to the local oscillator signal. The anode, the gates of the third PMOS transistor (MP3) and the fourth PMOS transistor (MP4) are connected to the positive pole of the local oscillator signal; the positive terminal of the third resistor (R3) is connected to the positive terminal of the third capacitor (C3), and the second transconductance is connected. The positive input terminal of the amplifier (A2), the negative terminal of the third resistor (R3) and the negative terminal of the third capacitor (C3) are connected to the negative output terminal of the second transconductance amplifier (A2); the positive of the fourth resistor (R4) The positive terminal of the fourth capacitor (C4) is connected to the negative input terminal of the second transconductance amplifier (A2), and the negative terminal of the fourth resistor (R4) and the negative terminal of the fourth capacitor (C4) are connected to the second transconductance amplifier. Positive output of (A2).

As shown in FIG. 2, the low-power single-ended input double-balanced passive mixer conversion gain curve of the present embodiment has a local oscillator frequency of 1 GHz; as can be seen from the figure, within a 20 MHz bandwidth near the local oscillator frequency. The conversion gain is approximately 24dB.

It can be seen from the above that the innovation of this embodiment is mainly embodied in the design of the transconductance stage. The traditional differential transconductance stage consists of independent differential branches whose output RF currents have opposite polarities and are injected into the differential branches of the local oscillator switch. To ensure bandwidth and noise performance, the transconductance bias current occupies a large proportion of the mixer, so reducing the transconductance current can significantly reduce the overall power consumption of the mixer. The invention provides a transconductance stage circuit which realizes two differential current outputs by using a single bias current; the circuit connects a PMOS current source and an NMOS current source respectively above and below the NMOS cross-duct, and utilizes the impedance of the passive mixing switch. Varying effect, pulling the output impedance of the transconductance stage at the local oscillator frequency and constructing an approximate AC virtual ground, the change of the input voltage will cause a change in the cross-conductor current, and the current flowing into the power supply and ground due to the transconductance stage is fixed, and The impedance of the source-drain across the conduit to the local oscillator switch is low enough, so the RF current generated is injected into the local oscillator switching stage, and the source and drain currents are equal in magnitude and opposite in phase. In passive mixers, the transconductance stage typically occupies most of the current consumption, and its bias current can be reduced by half compared to conventional differential structures with the same transconductance value. That is, the present invention saves half of the transconductance current, significantly reducing the overall power consumption.

The above description is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can also make several improvements and retouchings without departing from the principles of the present invention. It should be considered as the scope of protection of the present invention.

Claims

A single-ended input double-balanced passive mixer includes a balun transconductance stage, a passive local oscillator switch, and a transimpedance amplifier; the transconductance stage is responsible for converting an input RF voltage into an RF current; a passive local oscillator switch The RF current is frequency-converted; the transimpedance amplifier is responsible for converting the intermediate frequency current into an output intermediate frequency voltage, wherein the balun transconductance stage uses a single bias current to realize a dual differential current output transconductance stage circuit. The transconductance stage utilizes the impedance shifting action of the passive local oscillator switch to pull the output impedance of the transconductance stage at the local oscillator frequency and construct a similar AC virtual ground; when the input voltage changes, the cross-duct is pulled from the differential output end respectively. Current, a single bias current to achieve dual differential current output.
The single-ended input double-balanced passive mixer according to claim 1, wherein said balun transconductance stage comprises a first transconductance amplifier (A1), first, second, and third NMOS transistors, The first PMOS transistor has an input voltage connected to the gate of the third NMOS transistor (MN3), the source of the third NMOS transistor (MN3) is connected to the drain of the second NMOS transistor (MN2), and the source of the second NMOS transistor (MN2) The pole is grounded, and the gate is connected to the gate of the first NMOS transistor (MN1); the source of the first NMOS transistor (MN1) is grounded, and the gate and the drain are connected to the negative terminal of the reference current source, and the positive terminal of the reference current source Connected to the power supply; the drain of the third NMOS transistor (MN3) is connected to the drain of the first PMOS transistor (MP1), the source of the first PMOS transistor (MP1) is connected to the power supply, and the gate is connected to the first transconductance amplifier (A1) The output terminal; the negative input terminal of the first transconductance amplifier (A1) is connected to the reference voltage, and the positive input terminal is connected to the positive terminal of the first resistor (R1), and the negative terminal of the first resistor (R1) is connected to the first PMOS transistor ( The drain of the MP1); the positive terminal of the second resistor (R2) is connected to the positive input terminal of the first transconductance amplifier (A1), the negative terminal of the second resistor (R2) and the gate of the third NMOS transistor (MN3) Connected.
The single-ended input double-balanced passive mixer according to claim 2, wherein said passive local oscillator switch comprises first and second capacitors; and said positive terminal of said first capacitor (C1) The drain of the three NMOS transistor (MN3), and the negative terminal is connected to the source of the second PMOS transistor (MP2) and the source of the third PMOS transistor (MP3); the positive terminal of the second capacitor (C2) is connected to the third NMOS transistor The source of (MN3), and the negative terminal is connected to the source of the fourth PMOS transistor (MP4) and the source of the fifth PMOS transistor (MP5).
The single-ended input double-balanced passive mixer according to claim 3, wherein said transimpedance amplifier comprises a second transconductance amplifier (A2), and a drain of said second PMOS transistor (MP2) The drain of the fourth PMOS transistor (MP4) is connected to the negative input terminal of the second transconductance amplifier (A2), the drain of the third PMOS transistor (MP3) and the drain of the fifth PMOS transistor (MP5) are connected to the second transconductance The positive input terminal of the amplifier (A2); the gates of the second transconductance amplifier (A2) and the fifth PMOS transistor (MP5) are connected to the negative pole of the local oscillator signal, and the third PMOS transistor (MP3) and the fourth PMOS transistor (MP4) The gate is connected to the positive pole of the local oscillator signal; the positive terminal of the third resistor (R3) and the positive terminal of the third capacitor (C3) are connected to the second span The positive input terminal of the lead amplifier (A2), the negative terminal of the third resistor (R3) and the negative terminal of the third capacitor (C3) are connected to the negative output terminal of the second transconductance amplifier (A2); the fourth resistor (R4) The positive terminal of the positive terminal and the fourth capacitor (C4) are connected to the negative input terminal of the second transconductance amplifier (A2), and the negative terminal of the fourth resistor (R4) and the negative terminal of the fourth capacitor (C4) are connected to the second transconductance. Positive output of amplifier (A2).