CN1395372A

CN1395372A - Gilbert mixer with folding structure

Info

Publication number: CN1395372A
Application number: CN 02123630
Authority: CN
Inventors: 李永明; 陈弘毅; 林敏�
Original assignee: Tsinghua University
Current assignee: Tsinghua University
Priority date: 2002-07-05
Filing date: 2002-07-05
Publication date: 2003-02-05
Anticipated expiration: 2022-07-05
Also published as: CN1134114C

Abstract

The invention belongs to the technique area of the wireless communication receptor system related to the Gilbert mixer with folded structure. The mixer is the symmetric structure composed of the MOS tubes M1 and M2, M3 and M4, M5 and M6 as well as the resistors R1 and R2. The character is that the MOS tubes M3-M6 are PMOS tubes. The invention increases one degrees of freedom of the power consumption in the designing circuits, weakens the crossrelation among the noise, linearity and the conversion gain. Thus, the three targets can be optimized respectively. The cost paid directly for the optimization is the power consumption in the stead of deteriorating other targets.

Description

The gilbert mixer of foldable structure

Technical field

The invention belongs to wireless communication receiver systems technology field, particularly be used for the mixer design of wireless communication transceiver system front end.

Background technology

Over past ten years, the R and D of radio frequency integrated circuit (RFIC) have obtained swift and violent development, and this mainly should give the credit to the prosperity of wireless communications market.These wireless applications comprise beep-pager, cordless telephone, radio frequency authentication (RFID), analog-and digital-cellular mobile telephone and global positioning system (GPS) etc.Simultaneously along with the Internet is popularized mondial with surprising speed, the wireless communication system of some emerging short distances, high-speed transfer---wireless lan (wlan) also began to be able to develop rapidly over the past two years, mainly comprised IEEE802.11 series, HyperLAN, Bluetooth, HomeRF etc.The development of these wireless communication systems has formed a RFIC market that increases fast.Why radio circuit is subjected to mondial concern and research, is because it is the main bottleneck of whole wireless transceiver system design.In the element of radio frequency transceiver, the technical performance of RFIC requires to have constituted the ultimate challenge of RFIC.And meanwhile, the market user is again very harsh to the performance requirement of wireless product, i.e. low cost, low-power consumption, small size, high-performance etc., with original use bulky, cost dearly, power consumption again extremely the discrete component of waste realize that the method for transceiver compares, this is a very arduous challenge.

In the wireless receiver system, frequency mixer is a very crucial core circuit module, its noise, the linearity, performance index such as conversion gain have material impact to the selection of transceiver system structure, and to the noise of whole transceiver system, the linearity, sensitivity, performances such as dynamic range produce conclusive effect.Therefore, the design of frequency mixer is one of key technology of RFIC design always.

Frequency mixer is divided into two kinds of active mixer and passive frequency mixers.Active mixer generally adopts the topological structure of Gilbert (gilbert) frequency mixer, as shown in Figure 1.By metal-oxide-semiconductor M1 and M2, M3 and M4, the symmetrical structure that M5 and M6 and resistance R 1 and R2 form.Its annexation is: radio-frequency differential radiofrequency signal RF-P, RF-P imports from the grid of M1 and M2 respectively, the source-coupled of M1 and M2 also is connected on the constant-current source Iss, the drain electrode of M1 is received on the source electrode of M3 and M4, the drain electrode of M2 is then received on the source electrode of M5 and M6, M3 and M4, M5 and M6 form two source-coupled respectively to also receiving respectively in the drain electrode of M1 and M2, the drain electrode of M3 and the drain electrode of M5 are coupled and receive on the resistance R 1, the drain electrode of M4 and M6 is coupled and receives on the resistance R 2, difference local oscillation signal LO-P, LO-M and IF-M receive respectively on the grid of M3～M6, resistance R 1 and R2 receive on the power vd D, thereby constitute a traditional Gilbert (gilbert) mixer architecture.The operation principle of this frequency mixer is as follows: the trsanscondutor that M1 and M2 form is a current signal with the radio-frequency voltage conversion of signals, and M3～M6 is as switch, the opening and closing of switch are controlled by local oscillation signal, make flow through the frequency of electric current of resistance R 1 and R2 be radiofrequency signal and local oscillation signal difference frequency with and frequently, thereby finished the function of frequency inverted.

This frequency mixer biggest advantage is exactly that it has higher conversion gain, and this is for zero intermediate frequency or the receiver of Low Medium Frequency is vital.But it also has its some intrinsic defectives, and is relatively poor such as noise ratio, and the linearity is not very high or the like.Cause major reason and this circuit structure itself of this inherent shortcoming that much relations are arranged.Principle by circuit analysis is known, in order to reduce the output noise of circuit, must reduce to flow through the quiescent current of local oscillator M3～M6 pipe, but because the circuit structure that to be M1 pile up mutually with M2 and M3～M6 that traditional Gilbert (gilbert) structure adopts, reduce to flow through the electric current of M3～M6, simultaneously also just reduce to flow through the electric current of M1 and M2, and reduced the latter's electric current, will cause the conversion gain of circuit to descend and linearity deterioration.That is to say, conversion gain, the linearity and noise must be the improvement that cost just can be got self in return to sacrifice the other side, Here it is causes traditional Gilbert (gilbert) frequency mixer can't all obtain the reason of satisfactory performance on many index.

Summary of the invention

The objective of the invention is for overcoming the weak point of prior art, a kind of Gilbert (gilbert) mixer architecture of foldable structure is proposed, in the design of circuit, increased the degree of freedom of a power consumption, weakened noise, the interrelated degree of the linearity and conversion gain, can be optimized these three indexs respectively, and the direct cost that they are optimized is a power consumption, and no longer is the deterioration of other index.

The gilbert mixer of a kind of foldable structure that the present invention proposes, by metal-oxide-semiconductor M1 and M2, M3 and M4, M5 and M6 and resistance R 1 and R2 form symmetrical structure, it is characterized in that, and said metal-oxide-semiconductor M3～M6 is the PMOS pipe; Its annexation is: radio-frequency differential radiofrequency signal RF-P, R-FM import from the grid of M1 and M2 respectively, the source-coupled of M1 and M2 and direct ground connection, the drain electrode of M1 is received on the source electrode of M3 and M4, the drain electrode of M2 is then received on the source electrode of M5 and M6, M3 and M4, M5 and M6 form two source-coupled respectively to also receiving respectively in the drain electrode of M1 and M2, the drain electrode of M3 and the drain electrode of M5 are coupled and receive on the resistance R 2, the drain electrode of M4 and M6 is coupled and receives on the resistance R 1, difference local oscillation signal LO-P, LO-M receive respectively on the grid of M3～M6, and resistance R 1 and R2 receive ground.

The design of the Gilbert of this improved foldable structure of the present invention (gilbert) frequency mixer is compared with the traditional design scheme has following tangible advantage:

1) increased the degree of freedom of power consumption as circuit design and optimization, weakened noise greatly, the interrelated degree of the linearity and conversion gain makes that the design of circuit and optimization direction are clearer and more definite;

2) the PMOS pipe is littler than the l/f noise of NMOS pipe, adopts the effective switching tube of doing of PMOS, has reduced the switching noise of circuit output;

3) adopted the trsanscondutor of the directly grounded M1～M2 of source-coupled as radiofrequency signal, compared with the trsanscondutor that comes bias current with constant-current source Iss, the linearity has obtained improvement.

In sum, adopt Gilbert (gilbert) frequency mixer of foldable structure not only make frequency mixer design and optimize more simple and easy to doly, and on each performance index, also obtained good improvement.

Description of drawings

Fig. 1 is traditional Gilbert (gilbert) frequency mixer topological structure schematic diagram.

Fig. 2 is Gilbert (gilbert) the frequency mixer topological structure schematic diagram of foldable structure of the present invention.

Fig. 3 is Gilbert (gilbert) the frequency mixer example structure schematic diagram of foldable structure of the present invention.

Embodiment

Gilbert (gilbert) frequency mixer of the foldable structure that the present invention proposes reaches embodiment in conjunction with the accompanying drawings and is described in detail as follows:

Gilbert (gilbert) frequency mixer of the foldable structure that the present invention proposes as shown in Figure 2, by metal-oxide-semiconductor M1 and M2, M3 and M4, M5 and M6 and resistance R 1 and R2 form symmetrical structure.The particular circuit configurations and the annexation of each several part are described in detail as follows:

Radio-frequency differential radiofrequency signal RF-P, R-FM imports from the grid of M1 and M2 respectively, the source-coupled of M1 and M2 and direct ground connection, the drain electrode of M1 is received on the source electrode of M3 and M4, the drain electrode of M2 is then received on the source electrode of M5 and M6, M3 and M4, M5 and M6 form two source-coupled respectively to also receiving respectively in the drain electrode of M1 and M2, the drain electrode of M3 and the drain electrode of M5 are coupled and receive on the resistance R 2, the drain electrode of M4 and M6 is coupled and receives on the resistance R 1, difference local oscillation signal LO-P, LO-M receives respectively on the grid of M3～M6, resistance R 1 and R2 receive ground, thereby constitute Gilbert (gilbert) mixer architecture of foldable structure.

The core of foldable structure of the present invention is that M3～M6 is replaced with the PMOS pipe from the NMOS pipe.The operation principle basically identical of its operation principle and traditional Gilbert (gilbert) frequency mixer, but, as previously mentioned, in case adopted this folding structure, the optimization direction of the performance index that were mutually related is originally become simple more clear and definite, the easier design.On the other hand, adopted the directly grounded source-coupled linearity improvement that design designs than the trsanscondutor that adopts constant-current source to trsanscondutor, and noiseproof feature has obtained bigger improvement because having used the PMOS pipe instead.

Gilbert (gilbert) the frequency mixer embodiment of a kind of foldable structure of the present invention's design as shown in Figure 3, its basic structure is identical with Fig. 2, wherein, each metal-oxide-semiconductor has adopted the PMOS pipe, X in Fig. 3, the parasitic capacitance of two points of Y is bigger, and the radio-frequency leakage of these two points has material impact for the noiseproof feature of circuit, therefore, in order to reduce the radio-frequency leakage that these two points cause owing to parasitic capacitance, present embodiment can adopt two inductance L 3 and L4 to come to produce resonance with the parasitic capacitance of this point, thereby eliminates radio-frequency leakage, further improves noiseproof feature.On the other hand, in order further to improve the linearity of circuit, present embodiment can add inductance L 1 and L2 respectively between the source electrode of M1 and M2 and ground, make the input impedance of M1 and M2 under the situation that frequency and input signal amplitude change, keep stable, thereby improve circuit ground degree index further.The component parameter of present embodiment is as shown in table 1:

Table 1

Metal-oxide-semiconductor parameter (um) (W, L)						Inductance value (nH)				Resistance value (Ω)
Metal-oxide-semiconductor parameter (um) (W, L)						Inductance value (nH)				Resistance value (Ω)		?M1	?M2	?M3	?M4	?M5	?M6	?L1	?L2	?L3	?L4	?R1	?R2
?80	?80	?240	?240	?240	?240	?0.9	?0.9	?2	?2	?1K	?1K	?M1	?M2	?M3	?M4	?M5	?M6	?L1	?L2	?L3	?L4	?R1	?R2
?80	?80	?240	?240	?240	?240							?0.2	?0.2	?0.2	?0.2	?0.2	?0.2

Claims

1, a kind of gilbert mixer of foldable structure, by metal-oxide-semiconductor M1 and M2, M3 and M4, M5 and M6 and resistance R 1 and R2 form symmetrical structure, it is characterized in that, and said metal-oxide-semiconductor M3～M6 is the PMOS pipe; Its annexation is: radio-frequency differential radiofrequency signal RF-P, R-FM import from the grid of M1 and M2 respectively, the source-coupled of M1 and M2 and direct ground connection, the drain electrode of M1 is received on the source electrode of M3 and M4, the drain electrode of M2 is then received on the source electrode of M5 and M6, M3 and M4, M5 and M6 form two source-coupled respectively to also receiving respectively in the drain electrode of M1 and M2, the drain electrode of M3 and the drain electrode of M5 are coupled and receive on the resistance R 2, the drain electrode of M4 and M6 is coupled and receives on the resistance R 1, difference local oscillation signal LO-P, LO-M receive respectively on the grid of M3～M6, and resistance R 1 and R2 receive ground.

2, the gilbert mixer of foldable structure as claimed in claim 1 is characterized in that, is connected with inductance L 1 and L2 respectively between the source electrode of said M1 and M2 and ground, is connected with inductance L 3 and L4 in the drain electrode of said M1 and M2 respectively.