Frequency mixer and direct down-conversion receiver

Abstract

The invention discloses a frequency mixer which comprises a switching circuit, a down-conversion circuit, a load circuit and a capacitive impedance circuit, wherein, the frequency mixer comprises a switching tube M1 and a switching tube M2 connected in a differentiated way and is used for converting a radio-frequency voltage signal into a current signal, the down-conversion circuit comprises a common source switching tube pair M3, M4,, M5 and M6 connected in a differentiated way and is used for down-conversion of the current signal from the switching circuit to middle frequency or a baseband,the load circuit comprises a resistance R1 and a resistance R2 connected in a differentiated way and is used for converting the current signal after the down-conversion to a voltage signal, the capacitive impedance circuit is used for offsetting parasitic capacitance in common source point A of the switching tube pair M3 and M4 and / or the parasitic capacitance in common source point B of the switching tube pair M5 and M6. On the premise of not introducing extra power consumption, the frequency mixer and the direct down-conversion receiver in the invention can effectively eliminate flicker noise of the frequency mixer.

Description

technical field

[0001] The invention relates to the communication field, in particular to a low-noise down-conversion mixer and a direct down-conversion receiver. Background technique

[0002] In modern wireless communication equipment, a direct down conversion receiver (Direct Down Conversion Receiver) is more and more widely used due to its advantages of low cost and low power consumption.

[0003] The mixer is an important component in a direct down conversion receiver. The proportion of CMOS technology in the field of semiconductor manufacturing is gradually increasing. At present, the mixer of the direct down-conversion receiver usually adopts the Gilbert type mixer based on the CMOS technology.

[0004] The structure of the traditional Gilbert-type mixer in CMOS process is as follows figure 1 As shown, it is composed of RF input amplifier circuit, switch tube and load output circuit. The RF voltage signal is converted into a current signal by the input stage transco...

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