CN101414817B - Switch circuit - Google Patents
Switch circuit Download PDFInfo
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- CN101414817B CN101414817B CN2007101671111A CN200710167111A CN101414817B CN 101414817 B CN101414817 B CN 101414817B CN 2007101671111 A CN2007101671111 A CN 2007101671111A CN 200710167111 A CN200710167111 A CN 200710167111A CN 101414817 B CN101414817 B CN 101414817B
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Abstract
The invention provides a switching circuit which can adjust linearity. The switching circuit comprises two metal oxide semiconductor switches and an adjusting unit. A pair of differential input voltages is received at the input terminals of the two metal oxide semiconductor switches, and a pair of differential output voltages is output at the output terminals of the two metal oxide semiconductor switches when in conduction. The adjusting unit changes the difference of a common-mode level of the input terminals and the output terminals of the two metal oxide semiconductor switches, thus adjusting the linearity of differential mode resistances of the two metal oxide semiconductor switches.
Description
Technical field
The present invention relates to a kind of switching circuit, particularly relate to a kind of switching circuit that can adjust the linearity.
Background technology
The existing switching circuit that is used to transmit differential voltage comprises two metal oxide semiconductor switch (MOSSwitch), wherein, each metal oxide semiconductor switch comprises an input and an output, and can be a N type metal oxide semiconductor switch (NMOS Switch), a P-type mos switch (PMOS Switch) or a CMOS (Complementary Metal Oxide Semiconductor) switch (CMOS Switch).These two metal oxide semiconductor switch its input receive pair of differential input voltage vin+, Vin-, and when conducting at its output output pair of differential output voltage V out+, Vout-.
Fig. 1 and Fig. 2 have shown the relevant simulation result of this switching circuit 1, wherein, transverse axis represents that this is to differential input voltage Vin+, the difference Vdiff of Vin-, the longitudinal axis is represented the ratio (Rdiff that obtains during with Vdiff=0 is a benchmark) of the differential mode resistance R diff of these two metal oxide semiconductor switch, curve 21 obtains when these two metal oxide semiconductor switch are N type or P-type mos switch, curve 22 obtains when these two metal oxide semiconductor switch are the CMOS (Complementary Metal Oxide Semiconductor) switch, and shown in Vdiff and Rdiff be defined as follows:
Vdiff＝Vin+-Vin-，
Rdiff＝(Vin+-Vin-)/(Iin+-Iin-)，
Wherein, Iin+, Iin-are the pair of differential input currents that these two metal oxide semiconductor switch receive at its input.
By Fig. 1 and Fig. 2 as can be known, the differential mode resistance R diff of these two metal oxide semiconductor switch can change along with this difference Vdiff to differential input voltage Vin+, Vin-.When this switching circuit applies to a linear circuit (for example a filter or an amplifier), can limit the linearity of this linear circuit.
Summary of the invention
Therefore, purpose of the present invention is promptly providing a kind of switching circuit that can adjust the linearity.
So switching circuit of the present invention comprises two metal oxide semiconductor switch and an adjustment unit.Each metal oxide semiconductor switch comprises an input and an output.These two metal oxide semiconductor switch receive the pair of differential input voltage at its input, and export the pair of differential output voltage at its output when conducting.This adjustment unit changes the difference of the common mode electrical level of the input of these two metal oxide semiconductor switch and output, with the linearity of the differential mode resistance of adjusting these two metal oxide semiconductor switch.
Description of drawings
Fig. 1 is a simulation drawing, and the ratio of the differential mode resistance of this existing switching circuit is described when using N type or P-type mos switch;
Fig. 2 is a simulation drawing, and the ratio of the differential mode resistance of this existing switching circuit is described when using the CMOS (Complementary Metal Oxide Semiconductor) switch;
Fig. 3 is a circuit diagram, and first embodiment of switching circuit of the present invention is described;
Fig. 4 is a simulation drawing, and the differential mode resistance of this first embodiment is described;
Fig. 5 is a simulation drawing, and the ratio of the differential mode resistance of this first embodiment is described;
Fig. 6 is a simulation drawing, and is similar to Fig. 4, but the scope difference of partial parameters;
Fig. 7 is a simulation drawing, and is similar to Fig. 5, but the scope difference of partial parameters;
Fig. 8 is a simulation drawing, the ratio of differential mode resistance and 1 gap in the key diagram 7;
Fig. 9 is a circuit diagram, and second embodiment of switching circuit of the present invention is described;
Figure 10 is a circuit diagram, and the 3rd embodiment of switching circuit of the present invention is described; And
Figure 11 is a circuit diagram, and the situation that described embodiment can be used is described.
The reference numeral explanation
31,32 metal oxide semiconductor switch
5 adjustment units
The 501-504 current source
511-514 resistance
The 521-524 inductance
The 601-641 curve
651 points
71,72 electric capacity
Embodiment
About aforementioned and other technology contents, characteristics and effect of the present invention, in the detailed description of following cooperation three embodiment with reference to the accompanying drawings, can clearly present.
Before the present invention is described in detail, be noted that in the following description content similar elements is to represent with identical numbering.
Consult Fig. 3, first embodiment of switching circuit of the present invention comprises two metal oxide semiconductor switch 31,32 and an adjustment unit 5.Each metal oxide semiconductor switch 31,32 comprises an input and an output, and in the present embodiment, be a N type metal oxide semiconductor switch, but in other embodiments, can be a P-type mos switch or a CMOS (Complementary Metal Oxide Semiconductor) switch.These two metal oxide semiconductor switch 31,32 its input receive pair of differential input voltage vin+, Vin-, and when conducting at its output output pair of differential output voltage V out+, Vout-.
This adjustment unit 5 changes the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm of out, the linearity with the differential mode resistance R diff that adjusts these two metal oxide semiconductor switch 31,32, and Vcm, in, Vcm, shown in out, Vdcm and Rdiff are defined as follows:
Vcm，in＝(Vin++Vin-)/2，
Vcm，out＝(Vout++Vout-)/2，
Vdcm＝Vcm，in-Vcm，out，
Rdiff＝(Vin+-Vin-)/(Iin+-Iin-)，
Wherein, Iin+, Iin-are the pair of differential input currents that these two metal oxide semiconductor switch 31,32 receive at its input.
In the present embodiment, this adjustment unit 5 comprises four current source 501-504, wherein, these four current source 501-504 are electrically connected to the input and the output of these two metal oxide semiconductor switch 31,32 respectively, and the input of each metal oxide semiconductor switch 31,32 and output receive big or small in fact identical but electric current that direction is opposite from corresponding current source 501-504 respectively.For example, when these current source 501 injection currents arrive the input of this metal oxide semiconductor switch 31, this current source 502 can draw big or small in fact identical electric current (comparing with this current source 501) from the output of this metal oxide semiconductor switch 31, and vice versa.Produce the electric current of these two metal oxide semiconductor switch 31,32 of flowing through by described current source 501-504, the conducting resistance that cooperates these two metal oxide semiconductor switch 31,32, can change the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm of out.
Fig. 4 to Fig. 8 has shown the relevant analog result of present embodiment.Consult Fig. 4, transverse axis is represented this difference Vdiff to differential input voltage Vin+, Vin-, the longitudinal axis is represented the differential mode resistance R diff of these two metal oxide semiconductor switch 31,32, curve 601-605 is respectively at the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm=60mV of out, 30mV, 0V ,-30mV and-obtain during 60mV, and shown in Vdiff is defined as follows:
Vdiff＝Vin+-Vin-。
Consult Fig. 5, transverse axis is represented this difference Vdiff to differential input voltage Vin+, Vin-, the longitudinal axis is represented the ratio (Rdiff that obtains during with Vdiff=0 is a benchmark) of the differential mode resistance R diff of these two metal oxide semiconductor switch 31,32, curve 611-615 is respectively at the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm=60mV of out, 30mV, 0V ,-30mV and-obtain during 60mV.
By Fig. 4 and Fig. 5 as can be known, at the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm of out is during near 30mV, the variation of the differential mode resistance R diff of these two metal oxide semiconductor switch 31,32 is minimum, and when Vdcm more hour, Rdiff is littler, and has the big zone of healing make that the variation of Rdiff is very little near this difference Vdiff=0 to differential input voltage Vin+, Vin-.
Then, dwindle this scope, and increase the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the scope of the difference Vdcm of out the difference Vdiff of differential input voltage Vin+, Vin-.
Consult Fig. 6, transverse axis is represented this difference Vdiff to differential input voltage Vin+, Vin-, the longitudinal axis is represented the differential mode resistance R diff of these two metal oxide semiconductor switch 31,32, curve 621-627 is respectively at the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm=60mV of out, 30mV, 0V ,-30mV ,-60mV ,-90mV and-obtain during 120mV.
Consult Fig. 7, transverse axis is represented this difference Vdiff to differential input voltage Vin+, Vin-, the longitudinal axis is represented the ratio (Rdiff that obtains during with Vdiff=0 is a benchmark) of the differential mode resistance R diff of these two metal oxide semiconductor switch 31,32, curve 631-637 is respectively at the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm=60mV of out, 30mV, 0V ,-30mV ,-60mV ,-90mV and-obtain during 120mV.
Consult Fig. 8, transverse axis is represented the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm of out, the ratio of the differential mode resistance R diff of these two metal oxide semiconductor switch 31,32 and 1 gap in the longitudinal axis presentation graphs 7, curve 64 1 are to obtain during to the difference Vdiff=50mV of differential input voltage Vin+, Vin-at this.
By Fig. 6, Fig. 7 and Fig. 8 as can be known, though the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm of out exists one to separate and make that the variation of differential mode resistance R diff of these two metal oxide semiconductor switch 31,32 is minimum (as putting shown in 651), if but make the Vdcm little meeting of healing obtain another and separate, because this moment, Rdiff was less, and the variation of Rdiff is also very little.
Consult Fig. 9, second embodiment of switching circuit of the present invention comprises two metal oxide semiconductor switch 31,32, an adjustment unit 5 and two electric capacity 71,72.These two metal oxide semiconductor switch 31,32 its input respectively by this two electric capacity 71,72 receive pair of differential input voltage vin+, Vin-, and when conducting at its output output pair of differential output voltage V out+, Vout-.
This adjustment unit 5 comprises four resistance 511-514.The input of these two metal oxide semiconductor switch 31,32 is electrically connected to one first common-mode voltage by this two resistance 511,513 respectively, and output is electrically connected to one second common-mode voltage by this two resistance 512,514 respectively.This first and second common-mode voltage is set the input of these two metal oxide semiconductor switch 31,32 and the common mode electrical level Vcm of output, in, Vcm, out respectively.
Consult Figure 10, the 3rd embodiment of switching circuit of the present invention is similar to this second example, and difference is that present embodiment is to utilize four inductance 521-524 to replace this four resistance 511-514 respectively.
Because the relevant analog result of this second and third embodiment is similar with the relevant simulation of this first embodiment, no longer adds explanation herein.
Consult Figure 11, the foregoing description can be used in a variable gain amplifier (shown in Figure 11 (a)), be used for selecting by which received signal (shown in Figure 11 (b)) of two receivers, be used for selecting which of two transmitters sending signal (shown in Figure 11 (c)) by, and be used for selecting which output signal by two circuit, and not as limit to next stage circuit (shown in Figure 11 (d)).
Conclude above-mentioned, the present invention is by the input of these two metal oxide semiconductor switch 31,32 of change and the common mode electrical level Vcm of output, in, Vcm, the difference Vdcm of out, can adjust the linearity of the differential mode resistance R diff of these two metal oxide semiconductor switch 31,32, to reach purpose of the present invention.
The above person of thought, only be embodiments of the invention, when not limiting scope of the invention process with this, promptly the simple equivalent of being done according to the present patent application claim and invention description content generally changes and modifies, and all still belongs in the scope that patent of the present invention contains.
Claims (7)
1. switching circuit comprises:
Two metal oxide semiconductor switch, each metal oxide semiconductor switch comprises an input and an output, these two metal oxide semiconductor switch receive the pair of differential input voltage at its input, and export the pair of differential output voltage at its output when conducting; And
One adjustment unit changes the difference of the common mode electrical level of the common mode electrical level of input of these two metal oxide semiconductor switch and output, with the linearity of the differential mode resistance of adjusting these two metal oxide semiconductor switch;
Wherein the common mode electrical level of the common mode electrical level of input and output is respectively this mean value and this mean value to differential output voltage to differential input voltage, and
This differential mode resistance is defined at the ratio of the difference of the pair of differential input current of its input reception by these difference and this two metal oxide semiconductor switch to differential input voltage.
2. switching circuit according to claim 1, wherein, these two metal oxide semiconductor switch are N type metal oxide semiconductor switches.
3. switching circuit according to claim 1, wherein, these two metal oxide semiconductor switch are P-type mos switches.
4. switching circuit according to claim 1, wherein, these two metal oxide semiconductor switch are CMOS (Complementary Metal Oxide Semiconductor) switches.
5. switching circuit according to claim 1, wherein, this adjustment unit comprises four current sources, these four current sources are electrically connected to the input and the output of these two metal oxide semiconductor switch respectively,
Wherein, the input of each metal oxide semiconductor switch and output receive big or small in fact identical but electric current that direction is opposite from corresponding current source.
6. switching circuit according to claim 1, more comprise two electric capacity, wherein, these two metal oxide semiconductor switch receive this to differential input voltage by these two electric capacity respectively at its input, this adjustment unit comprises four resistance, the input of these two metal oxide semiconductor switch is electrically connected to one first common-mode voltage by two in this four resistance respectively, and output respectively by in this four resistance in addition two be electrically connected to one second common-mode voltage, this first and second common-mode voltage is set the input of these two metal oxide semiconductor switch and the common mode electrical level of output respectively.
7. switching circuit according to claim 1, more comprise two electric capacity, wherein, these two metal oxide semiconductor switch receive this to differential input voltage by these two electric capacity respectively at its input, this adjustment unit comprises four inductance, the input of these two metal oxide semiconductor switch is electrically connected to one first common-mode voltage by two in these four inductance respectively, and output respectively by in these four inductance in addition two be electrically connected to one second common-mode voltage, this first and second common-mode voltage is set the input of these two metal oxide semiconductor switch and the common mode electrical level of output respectively.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101671111A CN101414817B (en) | 2007-10-18 | 2007-10-18 | Switch circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2007101671111A CN101414817B (en) | 2007-10-18 | 2007-10-18 | Switch circuit |
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| Publication Number | Publication Date |
|---|---|
| CN101414817A CN101414817A (en) | 2009-04-22 |
| CN101414817B true CN101414817B (en) | 2011-08-10 |
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| CN2007101671111A Active CN101414817B (en) | 2007-10-18 | 2007-10-18 | Switch circuit |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103973249B (en) * | 2014-05-09 | 2017-01-25 | 华为技术有限公司 | Variable gain amplifier |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5729230A (en) * | 1996-01-17 | 1998-03-17 | Hughes Aircraft Company | Delta-Sigma Δ-Σ modulator having a dynamically tunable continuous time Gm-C architecture |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5729230A (en) * | 1996-01-17 | 1998-03-17 | Hughes Aircraft Company | Delta-Sigma Δ-Σ modulator having a dynamically tunable continuous time Gm-C architecture |
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