The utility model content
The purpose of this utility model aims to provide a kind of biasing device that is used to promote CMOS transistor I/O that does not require specific input voltage (for example, 3V or 5V all can).
The purpose of this utility model aims to provide a kind of under the situation of supply voltage, ambient temperature and course of work wide variation, and output still has the biasing device that is used to promote CMOS transistor I/O of constant rising and fall time.
A kind of biasing device that is used to promote CMOS transistor I/O comprises:
Produce the current source 12 of first output, connect Input voltage terminal, and its output current substantially constant;
Produce first amplifier 14 of second output, connect described current source 12, especially connect the output 24 of described first output, and this second output there is a gain with respect to first output;
Produce second amplifier 16 of the first biasing output, connect the output 30 of described second output;
And produce the 3rd amplifier 18 that second biasing is exported, connect the output 37 of the described first biasing output, and described first, second biasing output when being 2.7 volts to 7.0 volts scope, input voltage is linear.
The scope of described input voltage is 3 volts to 5 volts.
Described current source comprises a reference circuit, and described reference circuit comprises:
The first transistor M1, its grounded-grid, source electrode connects Input voltage terminal, and its drain electrode provides described first output;
Transistor seconds M2, its source electrode connects input voltage, and drain electrode connects the drain electrode of described the first transistor M1;
The 3rd transistor M3, its grid, drain electrode connect the drain electrode of described the first transistor M1;
The 4th transistor M4, its grid, drain electrode connect the source electrode of described the 3rd transistor M3, its source ground;
The 5th transistor M8, its source electrode connects described Input voltage terminal, and grid, drain electrode connect the grid of described transistor seconds M2;
The 6th transistor M9, its drain electrode connects the drain electrode of described the 5th transistor M8, and its grid connects the drain electrode of the described second crystal M2;
One resistance R 8, the source electrode of described the 6th transistor M9 of one termination, other end ground connection;
Also comprise a feedback circuit, it inserts described reference circuit.
Described feedback circuit comprises:
The first transistor MN3, its drain electrode connects described Input voltage terminal, and its grid connects the grid of the 5th transistor M8 of described reference circuit;
The first resistance R MN3, the one end is connected with the source electrode of described the first transistor MN3, other end ground connection;
Transistor seconds MP1, its grid is connected with the source electrode of described the first transistor MN3;
The second resistance R x2, its two ends all are connected with the source electrode of described transistor seconds MP1;
The 3rd resistance R mpd, the end of the described second resistance R x2 of one termination, the described input voltage of another termination;
The 4th resistance R x, the drain electrode of the described transistor seconds MP1 of a termination, other end ground connection;
The 3rd transistor MR8, its grid connects the drain electrode of described transistor seconds MP1, and its drain electrode, source electrode are connected to described resistance R 8 two ends, and source ground.
Described first amplifier comprises a plurality of transistors
Described first amplifier comprises:
The first transistor M10, its source electrode connects described input voltage, and grid connects the grid of the 5th transistor M8 of reference current in the described current source;
Transistor seconds M11, its drain electrode, grid are connected with the drain electrode of described the first transistor M10, and the drain electrode of described the first transistor M10 output is described second output;
And the 3rd transistor M12, its drain electrode is connected with the source electrode of described transistor seconds M11, and its grid and described first output are connected its source ground.
Described second amplifier comprises:
The first transistor M13, its source electrode connects described Input voltage terminal, its grounded-grid;
Transistor seconds M14, its source electrode is connected with the drain electrode of described the first transistor M13;
And the 3rd transistor M15, its grid and described second output are connected, and its drain electrode is connected with grid, the drain electrode of described transistor seconds M14 and provides described first to setover and export its source ground.
Described the 3rd amplifier comprises:
The first transistor M17, its grid is connected with the described first biasing output, and drain electrode provides the described second biasing output, and its source electrode connects described Input voltage terminal;
One resistance R 17, the one end is connected with the drain electrode of described the first transistor M17;
Transistor seconds M18, its grid, drain electrode are connected its source ground with the other end of described resistance R 17.
Described first amplifier forms an active load between described current source and described first amplifier.
Described second amplifier forms a current mirror between described first amplifier and the described first biasing output.
The utility model provides a kind of biasing device that is used to promote CMOS transistor I/O, can work under 3V, 5V or any power source voltage in this is interval and need not to carry out the adjustment of structure.The utility model is made of a current source and three amplifiers.Require in the design: under different operations and process condition, variation of ambient temperature or mains voltage variations as often occurring in the quick transistor process can provide constant electric current.This biasing device can adapt to above change condition.This biasing device generally provides two offset signals, can be used for promoting CMOS transistor I/O.
Object of the present utility model, characteristics and advantage are a kind of biasing device that is used to promote CMOS transistor I/O, can work under 3V, 5V or other power supplys in the 2.7-7V voltage range, and keep the constant rise or fall time.This biasing has the ability that the variation to voltage, temperature and process compensates, and remains low noise, high anti-power supply jamming rate and low jitter.
Embodiment:
With reference to circuit block 10 shown in Figure 2, imbody circuit connecting relation of the present utility model, circuit 10 by baseline current-source 12, first amplifier 14, second amplifier 16 and the 3rd amplifier 18 totally four parts form.First end of the source of the source of the source of the source of transistor M1, transistor M2, transistor M8, transistor MN3 and resistance R mpd all is connected to input voltage Vcc.Input voltage Vcc also appears on the input 20 of first amplifier 14.The grounded-grid of transistor M1.The grid of transistor M2 is connected to grid and the drain electrode of transistor M8, is also connected to transistorized source electrode.Transistor M9 is used to form feedback network TOUT2.Feedback network TOUT2 has improved the temperature of current source and the performance of the course of work, makes that output is more stable and constant.
The drain electrode that the drain electrode of transistor M2 is connected to transistor M1 forms a current source node A1.Current source node A1 is connected to the grid of transistor M9, and the drain and gate of transistor M3 equally also appears in first amplifier 14, and the source electrode of transistor M3 is connected to the drain and gate of transistor M4.The source ground of transistor M4.The source electrode of transistor M9 is received the drain electrode of transistor MR8, and an end of resistance R 8 is also received in the drain electrode of MR8.The other end of resistance R 8 is connected to the source electrode of transistor MR8, and ground connection together.The grid of transistor MR8 is received the drain electrode of transistor MP1, also receives the end of resistance R x.The other end ground connection of resistance R x.The grid of transistor MP1 is connected to the source electrode of transistor MN3, also receives the end of resistance R mn3.The other end ground connection of resistance R mn3.The source electrode of transistor MP1 is connected to the two ends of resistance R x2, and first end and second end have also connected first end of resistance R mpd.Second end of resistance R mpd is connected to first amplifier input terminal 20.The drain electrode of transistor MN3 is connected to the input 20 of first amplifier 14, and grid connects the grid of M8.
Transistor M1-M4, M8, M9 and resistance R 8 are formed the first of reference circuit, are similar to technology formerly.The first of reference circuit when changing as the course of work, temperature and power supply, provides the low-tension current of quite stable under the condition that is restricted.Add the compensation of the feedback circuit of forming by transistor MN3, MP1 and MR8 and resistance R mn3, Rx, Rx2 and Rmpd, even under the situation of the course of work, temperature and power supply generation wide variation, can also produce stable electric current.Particularly under higher temperature, electric current is descended, feedback circuit can compensate this influence.For example, in the fast course of work, when the voltage TOUT2 on the transistor MR8 grid reduced, the electric current by resistance R 8 can increase, and output 22 is raise.Thereby the electric current of transistor MR8 descends, and the result makes the total current by transistor M8 keep constant.Generally speaking, be the gain of restriction feedback control loop, the size of transistor MR8 remains on minimum.
First amplifier 14 is made up of transistor M10, transistor M11 and transistor M12.The input voltage Vcc of input 20 is connected to the source electrode of transistor M10 and the input 26 of second amplifier 16, and is connected with the 3rd amplifier 18 at input 28.The source electrode that the drain electrode of transistor M10 is connected to transistor M11 is connected with grid and with the input 30 of second amplifier 16, and grid connects the grid of transistor M8.The drain electrode of transistor M11 is connected to the drain electrode of transistor M12, the source ground of transistor M12 and the grid of transistor M12 connects input 24.
Transistor M12 is subjected to the biasing of current source node A1, so just significantly reduced since the variation of input voltage Vcc to the influence of circuit 10.In addition, also increased the range of linearity of circuit 10.The electric current that transistor M10 produces is constant substantially, and transistor M12 is as constant active load, to increase the gain of amplifier 14.The gate bias of transistor M12 connects current source node A1.Therefore directly do not concern between transistor M12 and the input voltage Vcc.The result has realized having high anti-power supply jamming rate and big linear working range when input voltage Vcc wide variation.Transistor M12 has positive temperature coefficient in its work, the result is the signal that produces on first amplifier 14 negative temperature coefficient of having proofreaied and correct current node 8 (being exactly under the higher temperature, to produce lower electric current) and the node 9.The signal that produces on the node 9 appears on the input 30 of second amplifier 16.In addition, the signal of node 9 generations is self-compensating to the variation of the course of work, temperature and power supply.
Second amplifier 16 is made up of transistor M13, transistor M14, transistor M15 and a transistor capacitance device 36.The source electrode of transistor M13 is accepted the input voltage Vcc of input 26, the grounded-grid of transistor M13, and the drain electrode of transistor M13 connects the source electrode of transistor M14.The drain and gate of transistor M14 connects together and receives the drain electrode of transistor M15.The grid of transistor M14 is received the 3rd amplifier input terminal 32 and the output of an Obrefn is provided.The grid of transistor M15 is accepted the signal from input 30.The source ground of transistor M15.The source electrode of transistor capacitance device 36 and the drain electrode ground connection that connects together.The grid of transistor 36 is received output Obrefn.
Transistor M13-M15 will amplify from the second level of input 30 acknowledge(ment) signals.Transistor M15 adopts the current mirror effect to produce a constant electric current.Generally speaking, when transistor M13 worked with linear model, transistor M14 and M15 were then with saturation mode work.In different temperature.Under the voltage and the course of work, can change across the source electrode of transistor M13 and the voltage of drain electrode, and guaranteed that transistor M14 and M15 can work under saturation mode, can export constant current.Therefore the voltage Obrefn of output 37 can play regulating action to the variation of input voltage Vcc, temperature and the course of work.Voltage Obrefn can provide and stable bias voltage for a transistor current source.
Third level amplifier 18 is made of transistor M17, transistor M18 and resistance R 17.The source electrode of transistor M17 connects input 28, to accept input voltage Vcc.The source electrode of transistor M17 is also received output 38.Transistor M17 drain electrode is received first end of resistance R 17 and is received output 40.Second end of resistance R 17 and the drain and gate of transistor M18 join.The source ground of transistor M18.The grid of transistor M17 is accepted the signal from input 32.Output 40 signal of an Obrefp occurs and is coupled to the grid of transistor capacitance device 42.The source electrode and the drain electrode of transistor 42 meet Vcc.
A complementary voltage Obrefp results from the 3rd amplifier 18.Transistor M17.Transistor M18 and resistance R 17 produce a back biased voltage Obrefp by the voltage Obrefn on the input 32.Bias voltage Obrefp also isolates mutually with input voltage Vcc, thereby has improved anti-power supply jamming rate.Bias voltage Obrefp provides the bias voltage of stabilizer pole for the NMOS current source.Under fast course of work condition, when bias voltage Obrefp shifted to ground, bias voltage Obrefn shifted to input voltage Vcc.Their cooperation the pulling on and leaving behind of connected transistor circuit of can slowing down, thus too fast conversion prevented.In addition, when other conditions changed, bias voltage Obrefp and Obrefn can corresponding adjusting transistor circuit make it speed-raising or deceleration, make the constant airspeed of change in voltage, and this will reduce noise widely.
Fig. 3 is a typical output buffer 50, and it is a kind of application of the present utility model.Transistor 58,60,64 draws predriver on forming one, and transistor 61,66,68 is formed a drop-down predriver.Transistor 62,70 is a driver.First inverter 54 and second inverter 56 are from input 52 acknowledge(ment) signals.On the output termination transistor 58 of first inverter 54 and the grid of transistor 60.On the source electrode of the source electrode of input voltage Vcc connection transistor 58, the source electrode of transistor 61 and transistor 62.The drain electrode of transistor 58 is connected with the drain electrode of transistor 60, is also connected to the grid of transistor 62.The source electrode of transistor 60 is connected to the drain electrode of transistor 64.The grid of transistor 64 is accepted the Obrefp signal from output 40.The source ground of transistor 64.The output of second inverter is received the grid of transistor 66 and transistor 68.The source electrode of transistor 66 is received the drain electrode of transistor 61.The drain electrode of the drain electrode of transistor 66 and transistor 68 links together and connects the grid of transistor 70.The source ground of transistor 68.The grid of transistor 61 is accepted from the Obrefn signal on the output 37 of second amplifier 16.The drain electrode of the drain electrode of transistor 62 and transistor 70 links together, and receives output 72.The source ground of transistor 70.Output 72 is by load capacitor 74 ground connection.
Formerly the relation curve of technology circuit Obref and Vcc is shown in Fig. 4, is respectively-55 ℃, and 25 ℃, 155 ℃ temperature, what transverse axis (VOL IS) was represented is input voltage, what the longitudinal axis (VOLT LIN) was represented is output voltage.The relation curve of the utility model Obrefn, Obrefp and Vcc is shown in Fig. 5, be respectively-35 ℃, 100 ℃, 25 ℃ of three kinds of temperature, wherein transverse axis (VOL IS) expression is input voltage, what the longitudinal axis (VOLT LIN) was represented is output voltage, and as seen when Vcc almost was lower than 4 volts, formerly the biasing device circuit of technology had not just been worked.
Detailed presentations of the present utility model is in this.Concerning those skilled in the art, make various changes in the form and details and all can not surpass essence of the present utility model and scope.