CN207719205U - A kind of RF switch - Google Patents

Abstract

The utility model discloses a kind of RF switch comprising：Substrate；The substrate contact region being formed in the substrate；The multiple RF switching units being formed in substrate, wherein each RF switching unit includes that the N+ source areas at the interval being formed in substrate and the drain regions N+, the grid oxic horizon positioned at the top of p-well region and between N+ source areas and the drain regions N+, the polysilicon gate above grid oxic horizon, the substrate contact region are connected with negative dc voltage source.Compared with prior art, RF switching unit in the utility model is not provided with well region, but substrate is connected with a negative voltage, the chip area shared by RF switch can be greatly reduced in this way, while also can guarantee tolerance power ability still to reach the requirement of middle low power switch.

Description

A kind of RF switch

【Technical field】

The utility model is related to semiconductor applications, more particularly to a kind of CMOS technology without trap RF switch.

【Background technology】

The RF switch of existing CMOS (Complementary Metal Oxide Semiconductor) technique is set Meter：Generally use triple-well process：Radiofrequency signal is isolated in p-well, Deep-nwell and p-sub tri- layers of trap, is penetrated with reaching raising The purpose of frequency pressure resistance.

Fig. 1 is a kind of existing cross section structure schematic diagram of the physical arrangement of the RF switch of CMOS technology.As shown in Figure 1 , the RF switch includes substrate p-sub and multiple RF switching units for being formed on the substrate p-sub, the lining It is formed in the p-sub of bottom in substrate contact region SUB, Fig. 1 and illustrates two RF switching units, actually it may include having More RF switching units.Each RF switching unit includes the deep N-well area Deep- being formed in the substrate p-sub Nwell, the p-well region p-well being formed in deep N-well area Deep-nwell, the deep N being formed in deep N-well area Deep-nwell Trap contact zone V_NW, N+ source area SOURCE, N+ drain region DRAIN at the interval being formed in p-well region p-well and p-well connect Touch area BODY, positioned at the top of p-well region p-well and the grid oxygen between N+ source area SOURCE and N+ drain region DRAIN Change layer 110, the polysilicon gate GATE above grid oxic horizon.The p-well contact zone BODY of wherein p-well region p-well connects The DC offset voltage connect is controlled by control signal, the direct current of the deep N traps contact zone V_NW connections of deep N-well area Deep-nwell Bias voltage general control is in ﹢ 3V or so, and the bias voltage of the substrate contact region SUB connections of substrate p-sub is usually to be connected to 0V(GND).Meanwhile in order to improve ac voltage withstanding, it will usually divide in such a way that multiple RF switching units stack (stack) Alternating voltage is carried on a shoulder pole, i.e., the source electrode of one RF switching unit can be connected with the drain electrode of adjacent RF switch, each RF switch The grid of unit can interconnect, and form concatenated RF switching unit combination.The deep N of adjacent RF switching unit There is certain interval between well region Deep-nwell.

This stacked structure, although the Insertion Loss of the RF switch of CMOS technology and isolation can be dropped to it is low as far as possible, But chip area is significantly increased, the spacing between deep N-well area is very important, leads to the RF switch 30% of CMOS technology Area be all wasted in the centre for stacking RF switching unit, and also lead to the area ratio SOI of the RF switch of CMOS technology The area of the RF switch of technique it is big it is many (under the conditions of same RF switch W/L (breadth length ratio), the face of CMOS RF switches Product is twice or so of SOI RF switches), this significantly impacts the universal of CMOS RF switches.

It is therefore desirable to provide a kind of new solution to solve the above problems.

【Utility model content】

One of the purpose of this utility model is to provide a kind of RF switch of improved CMOS technology, is not provided with trap The chip area shared by RF switch can be greatly reduced in area in this way.

In order to realize that the purpose of this utility model, the utility model provide a kind of RF switch comprising：Negative dc voltage Source；Substrate；The substrate contact region being formed in the substrate；The multiple RF switching units being formed in substrate, wherein each RF switching unit include the interval being formed in substrate N+ source areas and the drain regions N+, positioned at the top of p-well region and be located at N Grid oxic horizon between+source area and the drain regions N+, the polysilicon gate above grid oxic horizon, the substrate contact Area is connected with negative dc voltage source.The voltage in the negative dc voltage source of the substrate contact region connection of substrate is -3.5V.Multiple radio frequencies Switch unit is serially connected, and the source electrode of a RF switching unit can be connected with the drain electrode of adjacent RF switch, each radio frequency The grid of switch unit can interconnect.

Compared with prior art, the RF switching unit in the utility model is not provided with well region, but by substrate and one Negative voltage is connected, and the chip area shared by RF switch can be greatly reduced in this way, while also can guarantee tolerance power ability still The old requirement that can reach middle low power switch.

【Description of the drawings】

It will be better understood in conjunction with refer to the attached drawing and next detailed description, the utility model, wherein same attached drawing The corresponding same structure member of label, wherein：

Fig. 1 illustrates the schematic cross-section of the physical arrangement of existing RF switch；

Fig. 2 illustrates the schematic cross-section of the physical arrangement of the RF switch of the utility model.

【Specific implementation mode】

To keep the above objects, features, and advantages of the utility model more obvious and easy to understand, below in conjunction with the accompanying drawings and have Body embodiment is described in further detail the utility model.

Fig. 2 illustrates the schematic cross-section of the physical arrangement of the RF switch of the utility model.As shown in Fig. 2, institute RF switch is stated to include substrate p-sub, the substrate contact region SUB that is formed in the substrate p-sub, be formed in substrate p-sub Interior multiple RF switching units.Two RF switching units are illustrated in Fig. 2, actually it may include there are more to penetrate Frequency switch unit.Each RF switching unit includes N+ source areas SOURCE and the N+ leakage at the interval being formed in substrate p-sub Polar region DRAIN, positioned at the top of substrate p-sub and the grid between N+ source area SOURCE and N+ drain region DRAIN Oxide layer 210, the polysilicon gate GATE above grid oxic horizon.Multiple RF switching units are serially connected, and one is penetrated The source electrode of frequency switch unit can be connected with the drain electrode of adjacent RF switch, and the grid of each RF switching unit can be connected with each other Together, concatenated RF switching unit combination is formed.

In fig. 2, N+ source area SOURCE, N+ drain region DRAIN, the polysilicon gate of one of RF switching unit Pole GATE is respectively labeled as SOURCE1, DRAIN1, GATE1, N+ source areas SOURCE, N+ of another RF switching unit Drain region DRAIN, polysilicon gate GATE are respectively labeled as SOURCE2, DRAIN2, GATE2.

In this way, multiple RF switching units in the utility model can not use deep N-well area Deep-nwell and P The structure of well region p-well greatly reduces the area of RF switching unit occupancy.

When RF switch in Fig. 1 is in the conduction state, high-power RF signal is in drain D RAIN and source electrode SOURCE can occur, and according to currently existing scheme, SUB connects AC deposition (GND), then drain D RAIN and source S OURCE are just Pressure resistance to access (from drain D RAIN and source S OURCE to substrate) is Vr11+Vd12+Vr13, drain D RAIN and source electrode The pressure resistance of the backward channel (from substrate to drain D RAIN and source S OURCE) of SOURCE is Vd11+Vr12+Vd13, wherein Vr11, Vr12, Vr13 indicate the reverse bias voltage of parasitic diode D11, D12, D13, Vd11, Vd12, Vd13 difference respectively Indicate the forward bias voltage of parasitic diode D11, D12, D13, it is contemplated that the 3.3V CMOS technologies of standard, general diode Reverse bias voltage Vr=8V, forward bias voltage Vd=1V, calculate in this way, the maximum of forward path and backward channel is resistance to Pressure is 17V and 10V respectively, therefore minimum withstanding voltage is about just 10V.

As shown in Fig. 2, after RF switching unit using no trap, substrate p-sub to SOURCE/DRAIN just only there are one Parasitic diode D1, as SOURCE/DRAIN plus negative voltage, RF switching unit can only be resistant to the negative voltage of 1V, and (D1 is just To conducting), that is, 13dBm power, this is far from the requirment.

The DC voltage that the utility model connects substrate p-sub as a result, is reduced into negative voltage, to balance positively and negatively Power capability.The i.e. described substrate contact region SUB is connected with a negative dc voltage source (not shown).According to Vd=1V, Vr= 8V is calculated, wherein Vd is diode D1 forward conduction voltage drops, and Vr is diode D1 breakdown reverse voltages, it should by substrate contact The voltage bias of area SUB is in (1-8)/2=-3.5V.Under these conditions, the maximum pressure resistance point of forward path and backward channel It is not 4.5V and 4.5V, the power that RF switch is resistant to is 26dBm.And the RF switch of three trap cmos techniques is used, generally Power tolerance is between 31dBm~32dBm.Certainly, the voltage value in the negative dc voltage source can also be -3V to -4V Between other values.

To sum up, can be by the area reduction half or so of RF switch by the design of the utility model, while tolerance power Ability can still reach the requirement of middle low power switch.

Above description fully discloses specific embodiment of the present utility model.It should be pointed out that being familiar with the neck Right of any change that the technical staff in domain does specific embodiment of the present utility model all without departing from the utility model The range of claim.Correspondingly, the scope of the claims of the utility model is also not limited only to the specific embodiment party Formula.

Claims (3)

1. a kind of RF switch, which is characterized in that it includes：

Substrate；

Negative dc voltage source；

The substrate contact region being formed in the substrate is connected with the negative dc voltage source；

The multiple RF switching units being formed in substrate；With

Wherein each RF switching unit include the interval being formed in substrate N+ source areas and the drain regions N+, be located at p-well region Top and the grid oxic horizon between N+ source areas and the drain regions N+, the polysilicon gate above grid oxic horizon Pole.

2. RF switch according to claim 1, which is characterized in that the negative dc voltage of the substrate contact region connection of substrate The voltage in source is -3V to -4V.

3. RF switch according to claim 1, which is characterized in that multiple RF switching units are serially connected, and one is penetrated The source electrode of frequency switch unit can be connected with the drain electrode of adjacent RF switch, and the grid of each RF switching unit can be connected with each other Together.