KR-20260063636-A - Active frequency mixer and frequency mixing method with improved gain and noise

KR20260063636AKR 20260063636 AKR20260063636 AKR 20260063636AKR-20260063636-A

Abstract

A technology relating to an active frequency mixer with improved gain and noise is disclosed. An active frequency mixer comprising a magnetically coupled inductor includes a transconductance section that outputs a current corresponding to an input RF signal, a switching section that converts the frequency of the RF signal using a local oscillation signal, a load section electrically connected between the switching section and a power terminal, and a current bleeding section connected in parallel with the load section to output a bleeding current to the switching section. In particular, the frequency mixer comprises a first inductor connected to the output terminal of the current bleeding section and a second inductor connected between the transconductance section and the switching section, which are magnetically coupled to the first inductor. The frequency mixer according to the present invention can be implemented using a transformer, thereby improving noise and conversion gain performance without increasing size or power consumption.

Inventors

한정환
김준협
김주성

Assignees

충남대학교산학협력단
국립한밭대학교 산학협력단

Dates

Publication Date: 20260507
Application Date: 20241030

Claims (11)

In an active frequency mixer comprising a magnetically coupled inductor, A transconductance section that receives an RF signal and outputs a current corresponding to the input signal; A switching unit that converts the frequency of the signal output from the above transconductance unit using a local oscillation signal and outputs the converted frequency signal; A load unit electrically connected between the above-mentioned switching unit and power terminal; A current bleeding unit connected in parallel with the load unit and outputting a bleeding current to the switching unit; A first inductor part having a first inductor having one end electrically connected to the output terminal of the current bleeding part; and A second inductor section having a second inductor electrically connected between the output terminal of the transconductance section and the input terminal of the switching section; The first inductor and the second inductor are magnetically coupled to each other. Frequency mixer.
In paragraph 1, The first inductor and the second inductor are composed of a transformer. Frequency mixer.
In paragraph 1, The first inductor and the second inductor are, Composed of a transformer in which each coil is positioned internally or externally relative to each other, or is formed by stacking vertically, Frequency mixer.
In paragraph 1, The above-mentioned first inductor is, A signal having the same phase as the current input from the second inductor to the switching unit is induced and output to the switching unit. Frequency mixer.
In paragraph 1, The above second inductor is, Configured to induce a signal having a phase opposite to the bleeding current flowing in the first inductor and output it to a switching unit, Frequency mixer.
In paragraph 1, The above switching unit is, Consisting of four transistors in a double-balanced Gilbert cell configuration, Frequency mixer.
In paragraph 1, The above transconductance section is, Consisting of differential pairs to amplify the difference between two input signals, Frequency mixer.
A low-noise amplifier that amplifies and outputs an RF signal received by an antenna; A local oscillator that outputs an oscillation signal having a frequency different from the frequency of the RF signal; A frequency mixer according to any one of claims 1 to 7, which receives the output signal of the low-noise amplifier and the oscillation signal of the local oscillator and outputs a signal having a frequency converted from an RF signal; and A low-pass filter that receives the output signal of the above-mentioned frequency mixer and outputs a signal having a frequency lower than a predetermined threshold frequency; comprising Communication device.
In the method of mixing frequencies, A step of receiving an RF signal in a transconductance section, amplifying the input signal based on the transconductance, and outputting the amplified current to a switching section; A step of converting the frequency of a signal amplified based on transconductance in a switching unit using a local oscillation signal, and outputting the converted frequency signal; A step of electrically connecting the power terminal to the switching unit using a load; A step of outputting a bleeding current to a switching unit from a current bleeding unit connected in parallel with the load; A step of electrically connecting one end of the first inductor to the output terminal of the current bleeding section; A step of electrically connecting a second inductor between the output terminal of the transconductance section and the input terminal of the switching section; and A step of magnetically coupling the first inductor and the second inductor to each other; comprising Frequency mixing method.
In Paragraph 9, The method further comprises the step of, when current is input from the second inductor to the switching unit, inducing a signal having the same phase as the current flowing in the second inductor in the first inductor and outputting it to the switching unit. Frequency mixing method.
In Paragraph 9, The method further comprises the step of, when a bleeding current flows through the first inductor, inducing a signal having a phase opposite to that of the current flowing through the first inductor in the second inductor and outputting it to the switching unit. Frequency mixing method.

Description

Active frequency mixer and frequency mixing method with improved gain and noise The present invention relates to a frequency mixer that converts the frequency of an RF signal by a local vibration signal, and in particular to an active frequency mixer capable of improving gain and noise by using a coupled inductor or transformer. As reception systems for various frequency bands, such as 5/6G mobile communication and MICS (Medical Implant Communication System), develop, support for wide frequency bands is constantly required. In addition, fields requiring increasingly ultra-low power consumption, such as quantum computing and IoT, are on the rise. The Direct Conversion Receiver (DCR) is a suitable structure for improving low-cost and low-power characteristics. However, when designed based on CMOS, it suffers from poor noise characteristics and low conversion gain performance, requiring a low-noise and high-gain design. In the case of the Gilbert-cell-based Direct-Conversion Active Mixer, which is commonly used in Direct-Conversion Receivers (DCRs), there is the advantage of being able to obtain high gain, but there is a problem in that flicker noise, a low-frequency noise, appears in the output. Therefore, in the case of the Direct-Conversion Active Mixer, it is essential to reduce this low-frequency flicker noise. In order to compensate for flicker noise in a direct conversion frequency mixer (mixer), a method of applying a static current bleeding circuit or a dynamic current bleeding circuit to a Gilbert cell-based active frequency mixer structure is being used. A method of applying a static current bleeding circuit improves flicker noise by reducing the DC current of the switching device of the frequency mixer while maintaining the gain of the transconductance stage. However, in the case of a static current bleeding circuit, continuously reducing the current over the entire signal cycle increases the input resistance of the switching device. This causes more radio frequency (RF) signals to leak into the parasitic capacitance path, thereby reducing the conversion gain of the frequency mixer. Additionally, there is a disadvantage in that the mixer conversion gain is further reduced due to the increase in additional parasitic capacitance ( CP ) caused by the added static current bleeding circuit. The method of applying a dynamic current bleeding circuit involves applying a dynamic current bleeding structure that bleeds current only during the switching section of the mixer where flicker noise mainly occurs. Therefore, compared to a static current bleeding structure, RF signal leakage is reduced by keeping the input resistance of the switching device in the on state low, thereby improving the conversion gain and noise performance of the entire mixer. However, there is still a problem with the influence of parasitic capacitance ( CP ) caused by the added dynamic current bleeding circuit. Meanwhile, a structure with an added inductor can be used to eliminate the effect of parasitic capacitance ( CP ) caused by static/dynamic current bleeding circuits. In this case, by resonating the inductor with the parasitic capacitance ( CP ) at the operating frequency, the effect of the parasitic capacitance ( CP ) can be reduced. However, in the case of a direct conversion frequency mixer structure, although the effects of flicker noise and parasitic capacitors can be improved, there is a disadvantage that the conversion gain is still reduced and thermal noise is increased compared to a Gilbert cell active mixer without a current bleeding circuit due to additional noise and leakage signals from the device of the added bleeding circuit. Registered Patent No. 10-1390037, published on April 29, 2014, relates to a "frequency mixer." In order to realize high gain, low noise, and low power, a frequency mixer is disclosed comprising an input section that receives RF signals and a current bleeding section connected to the input section. In particular, the current bleeding section is disclosed to have a configuration including at least one inductor that prevents RF signals from being mixed and canceled out. FIG. 1 is a schematic diagram showing the schematic configuration of a direct conversion receiver using a frequency mixer according to one embodiment of the present invention. FIGS. 2a and FIGS. 2b are a configuration diagram and a circuit diagram showing the main configuration of a frequency mixer according to the prior art. FIGS. 3a, FIGS. 3b, and FIGS. 3c are configuration diagrams and circuit diagrams showing the main configuration of a frequency mixer including a current bleeding circuit according to the prior art. FIGS. 4a, FIGS. 4b, and FIGS. 4c are schematic diagrams showing the main configuration of a frequency mixer according to one embodiment of the present invention. FIG. 5 is a circuit diagram specifically showing a frequency mixer according to a variation of one embodiment of the present invention. FIG. 6 is a circu