The AC-DC converter that a kind of high efficiency is fully integrated
Technical field
The present invention relates to technical field of integrated circuits, the AC-DC converter that especially a kind of high efficiency is fully integrated.
Background technology
More and more be widely used in causing battery to use inconvenience maybe cannot install in the system of battery, as biologic medical implant devices, wireless radio frequency identification mark and close range wireless communication equipment etc. because of factors such as battery size, useful life and cost control based on inductive coupled radio source transmission technology.This energy autonomous system based on inductance coupling high comprises 3 parts usually: reader, induction coil and transponder.The carrier signal that reader is sent by induction coil by transponder obtains, and by AC-DC converter, AC signal is converted to direct voltage.As shown in Figure 1, usual AC-DC converter comprises rectification and voltage stabilizing two parts to traditional radio source transmission system block diagram, and each part needs a larger coupling capacitance.
Rectifier is used to device AC signal being converted to direct current signal.The most basic rectifier is diode rectifier, but be no matter the MOSFET(metal-oxide layer-semiconductor-field-effect transistor with rectifier diode or diode-connected) all can there is larger conduction voltage drop, limit amplitude and the voltage conversion efficiency of input signal, so the diode rectifier of routine is seldom used in an integrated system.Nearly ten years, the full-wave rectifier based on active diode becomes main flow.This full-wave rectifier adopts four power transistors, consistent with the flow direction that cut-off realizes electric current by the conducting controlling them.Therefore, theoretically, the difference of output-input voltage only by conducting resistance and the load current decision of transistor, and has nothing to do with the threshold voltage of power transistor, thus significantly reduces the internal power consumption of rectifier, substantially increases conversion efficiency.In fact, the subject matter affecting its efficiency under this structure is the stationary problem of transistor: when load is larger, transistor needs to be designed to large scale to meet the requirement of current density and efficiency, but the grid capacitance of large-sized transistor is larger, cause the discharge and recharge time longer, such rectifier easily forms reverse-conducting path relatively for a long time in high frequency, have impact on the efficiency of rectifier.Therefore, the reverse-conducting path formed because of transistor simultaneously conducting how is avoided to be the difficult point place of rectifier design.
The direct voltage that rectifier exports is changed significantly by the factors such as the relative distance of induction coil and angle affect, ripple comparatively greatly, so also need a pressurizer to obtain a galvanic current pressure after transponder rectification.For wireless energy transfer system circuit, the most basic demand of pressurizer is exactly low speed paper tape reader static power disspation.Add Cost Problems, without the need to inductance and the linear voltage regulator (LDO) being easy to fully-integratedization just becomes the first-selection of this kind of application.But the quiescent current of LDO is extremely low, mapping is more weak and the rejection ability of power supply noise is lower.In addition, in order to improve integrated level, wireless energy transfer system circuit will reduce the outer bulky capacitor of sheet as far as possible.So without the outer output capacitance of sheet, transient response fast, the high and low quiescent dissipation of Power supply rejection ability and stable LDO be the difficult point place of regulator design.
For the biologic medical implant devices needing fully integrated and low cost, the performance and the saving area that improve AC-DC converter are two key issues needing to consider.The index weighing AC-DC converter performance quality AC signal is converted into the ability of DC signal and provides the ability of voltage and current, specifically, is exactly the ripple of power conversion efficiency (PCE) and voltage conversion efficiency and output.Current rectifier generally can only reach the power conversion efficiency of less than 82%, and the power conversion efficiency of LDO can reach about 95%, so the PCE of whole AC-DC converter is
.Voltage conversion efficiency (VCR) is relevant with the size of output impedance and the pressure drop of each element of signal transmission loop, and the pressure drop of whole AC-DC converter comprises rectification pressure drop and these two parts of voltage stabilizing pressure drop.Output ripple is then relevant with output capacitance, and rectifier generally has a large storage capacitance, and pressurizer also needs a large electric capacity of voltage regulation, and these two output capacitances are generally in μ F magnitude, take too large chip area, are unfavorable for integrated.If reduction output capacitance, need again to consider the problem of stability and the method for Ripple Suppression.
For output capacitance this problem large, T.J Sun proposes a kind of new circuit structure---rectifying pressurizer (rectigulator), rectifier and pressurizer are combined, directly AC signal is converted into stable DC signal output, thus save rectifier bulky capacitor below, but it still needs the electric capacity of a μ F level, as shown in Figure 2.Fig. 3 gives the physical circuit schematic diagram of the rectigulator that T.J Sun proposes.This circuit is made up of following four parts: four transistors, two operational amplifiers, two alternative MUX and direct voltage bleeder circuits.Wherein, four transistors (M1, M2, M3 and M4) are the main paths of AC-DC converter, and the grid of transistor M1 and M2 is driven by operational amplifier, alternate conduction, by the signal from ac input end to DC output end; Transistor M3 and M4 is that grid intersects (cross-gate) structure, and alternate conduction, by by the direct current signal of ground to ac input end.This structure can be regarded as and have shared pair of transistor by the active diode rectifier of general operational amplifier driving and LDO, while rectification, carry out voltage stabilizing.And the output of this structure only needs an electric capacity, this electric capacity is simultaneously as the storage capacitance of rectifier and the electric capacity of voltage regulation of pressurizer.But in this structure, the input end signal of operational amplifier is the pulse wave signal produced by MUX, and this signal is the drive singal being similar to dc-dc switching tube, therefore exports and have larger noise.Secondly, the active diode of still operational amplifier driving on this structural nature, when the higher luck of frequency is left with in offset(skew), cause the formation of leakage current, reduce further conversion efficiency.
Summary of the invention
In order to solve the problems of the technologies described above, the object of the invention is: provide a kind of and be easy to integrated, output ripple is little and there is not reverse leakage current, the AC-DC converter that high efficiency is fully integrated.
The technical solution adopted for the present invention to solve the technical problems is:
The AC-DC converter that a kind of high efficiency is fully integrated, comprise the first AC signal input port, second AC signal input port, first linear voltage regulator, second linear voltage regulator, ground connection output port, DC output end mouth and the three grid chi structures that are made up of the first transistor to the 6th transistor are from control rectifier, described first AC signal input port respectively with the source electrode of the first transistor, the grid of transistor seconds, the drain electrode of third transistor is connected with the grid of the 4th transistor, the source electrode of described third transistor is connected with the source electrode of the 4th transistor, the grid of described third transistor is all connected with DC output end mouth with the drain electrode of the 4th transistor, described first linear voltage regulator parallel join is between the source electrode and drain electrode of the 4th transistor, described second AC signal input port is connected with the grid of the grid of the first transistor, the source electrode of transistor seconds, the drain electrode of the 5th transistor and the 6th transistor respectively, the source electrode of described 5th transistor is connected with the source electrode of the 6th transistor, the grid of described 5th transistor is all connected with DC output end mouth with the drain electrode of the 6th transistor, and described second linear voltage regulator parallel join is between the source electrode and drain electrode of the 6th transistor, the drain electrode of described the first transistor is all connected with ground connection output port with the drain electrode of transistor seconds.
Further, described the first transistor meets to the relation of the 6th transistor: if the voltage of the first AC signal input port is greater than the voltage of DC output end mouth, then transistor seconds and the equal conducting of third transistor, the first transistor, the 4th transistor and the 5th transistor all end; If the voltage of the first AC signal input port is less than the voltage of DC output end mouth, then transistor seconds and third transistor are all ended, the first transistor and the equal conducting of the 4th transistor; If the voltage of the second AC signal input port is greater than the voltage of DC output end mouth, then the first transistor and the equal conducting of the 5th transistor, transistor seconds, third transistor and the 6th transistor all end; If the voltage of the second AC signal input port is less than the voltage of DC output end mouth, then the first transistor and the 5th transistor all end, transistor seconds and the equal conducting of the 6th transistor.
Further, described first linear voltage regulator or the second linear voltage regulator comprise first order amplifying circuit, second level amplifying circuit, third level amplifying circuit, feedforward diode, high pass filter and miller compensation electric capacity, described first order amplifying circuit comprises bias current mirror, Differential input circuit and current mirror load, described second level amplifying circuit comprises common source amplifier transistor and Current amplifier current mirror, described third level amplifying circuit comprises the 7th transistor and load, the source electrode of described 7th transistor respectively with the negative electrode of feedforward diode, Current amplifier current mirror is connected with one end of bias current mirror, the other end of described bias current mirror is connected with Differential input circuit, one input of described Differential input circuit is connected with load, another input termination reference voltage of described Differential input circuit, described Differential input circuit is also connected with current mirror load, described current mirror load is also connected with miller compensation electric capacity and common source amplifier transistor respectively, described miller compensation electric capacity is connected with DC output end mouth, the grid of described 7th transistor is connected with the anode of feedforward diode, Current amplifier current mirror and high pass filter respectively, described current mirror load, common source amplifier transistor are all connected with ground connection output port with high pass filter, and described Current amplifier current mirror and high pass filter also all connect input voltage, the drain electrode of described 7th transistor is connected with load and DC output end mouth respectively.
Further, described bias current mirror is PMOS current mirror, and described current mirror load is NMOS current mirror, and described Differential input circuit is PMOS differential pair tube input circuit.
Further, described the first transistor and transistor seconds are NMOS tube, and described third transistor, the 4th transistor, the 5th transistor, the 6th transistor and the 7th transistor are PMOS.
The invention has the beneficial effects as follows: rectifier and pressurizer are combined, save rectifier bulky capacitor below, output capacitance is little, is easy to integrated and output ripple is little; Comprise three grid chi structures from control rectifier, MUX is replaced from the mode controlled with three grid chi structures, without the need to the pulse wave signal that MUX produces, solve the reverse leakage flow problem of active diode structure, ensure that the efficiency of conversion.Further, linear voltage regulator comprises Differential Input amplifying stage, high-gain stage, high pass filter, feedforward diode, miller compensation electric capacity and the 7th transistor, the method that feedforward worked in coordination with by the transistor be connected with diode by high pass filter improves the Power supply rejection ability of linear voltage regulator, further reduces output ripple.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the invention will be further described.
Fig. 1 is the theory diagram of conventional wireless power delivery system;
Fig. 2 is the theory diagram of the radio source transmission system based on rectigulator structure;
Fig. 3 is the circuit theory diagrams of rectigulator structure;
Fig. 4 is the circuit theory diagrams of the fully integrated AC-DC converter of a kind of high efficiency of the present invention;
Fig. 5 is the circuit theory diagrams of the present invention first linear voltage regulator or the second linear voltage regulator.
Embodiment
With reference to Fig. 4, the AC-DC converter that a kind of high efficiency is fully integrated, comprise the first AC signal input port AC1, second AC signal input port AC2, first linear voltage regulator LLDO, second linear voltage regulator RLDO, ground connection output port, DC output end mouth DC Output and the three grid chi structures that are made up of to the 6th transistor M1 ~ M6 the first transistor are from control rectifier, described first AC signal input port AC1 respectively with the source electrode of the first transistor M1, the grid of transistor seconds M2, the drain electrode of third transistor M3 is connected with the grid of the 4th transistor M4, the source electrode of described third transistor M3 is connected with the source electrode of the 4th transistor M4, the grid of described third transistor M3 is all connected with DC output end mouth DC Output with the drain electrode of the 4th transistor M4, described first linear voltage regulator LLDO parallel join is between the source electrode and drain electrode of the 4th transistor M4, described second AC signal input port AC2 is connected with the grid of the grid of the first transistor M1, the source electrode of transistor seconds M2, the drain electrode of the 5th transistor M5 and the 6th transistor M6 respectively, the source electrode of described 5th transistor M5 is connected with the source electrode of the 6th transistor M6, the grid of described 5th transistor M5 is all connected with DC output end mouth DC Output with the drain electrode of the 6th transistor M6, and described second linear voltage regulator RLDO parallel join is between the source electrode and drain electrode of the 6th transistor M6, the drain electrode of described the first transistor M1 is all connected with ground connection output port with the drain electrode of transistor seconds M2.
Be further used as preferred embodiment, described the first transistor M1 meets to the relation of the 6th transistor M6: if the voltage of the first AC signal input port AC1 is greater than the voltage of DC output end mouth DC Output, the then equal conducting of transistor seconds M2 and third transistor M3, the first transistor M1, the 4th transistor M4 and the 5th transistor M5 all end; If the voltage of the first AC signal input port AC1 is less than the voltage of DC output end mouth DC Output, then transistor seconds M2 and third transistor M3 all ends, the first transistor M1 and the equal conducting of the 4th transistor M4; If the voltage of the second AC signal input port AC2 is greater than the voltage of DC output end mouth DC Output, then the first transistor M1 and the equal conducting of the 5th transistor M5, transistor seconds M2, third transistor M3 and the 6th transistor M6 all end; If the voltage of the second AC signal input port AC2 is less than the voltage of DC output end mouth DC Output, then the first transistor M1 and the 5th transistor M5 all ends, transistor seconds M2 and the equal conducting of the 6th transistor M6.
With reference to Fig. 5, be further used as preferred embodiment, described first linear voltage regulator or the second linear voltage regulator comprise first order amplifying circuit 1, second level amplifying circuit 2, third level amplifying circuit 3, feedforward diode 4, high pass filter 5 and miller compensation electric capacity Cm, described first order amplifying circuit 1 comprises bias current mirror 11, Differential input circuit 12 and current mirror load 13, described second level amplifying circuit comprises common source amplifier transistor 21 and Current amplifier current mirror 22, described third level amplifying circuit comprises the 7th transistor M7 and load load, the source electrode of described 7th transistor M7 respectively with the negative electrode of feedforward diode 4, Current amplifier current mirror 22 is connected with one end of bias current mirror 11, the other end of described bias current mirror 11 is connected with Differential input circuit 12, one input of described Differential input circuit 12 is connected with load load, another input termination reference voltage V ref of described Differential input circuit 12, described Differential input circuit 12 is also connected with current mirror load 13, described current mirror load 13 is also connected with miller compensation electric capacity Cm and common source amplifier transistor 21 respectively, described miller compensation electric capacity Cm is connected with DC output end mouth DC Output, the grid of described 7th transistor M7 is connected with the anode of feedforward diode 4, Current amplifier current mirror 22 and high pass filter 5 respectively, described current mirror load 13, common source amplifier transistor 21 are all connected with ground connection output port with high pass filter 5, and described common-battery banishes big current mirror 22 and high pass filter 5 also all connects input voltage VIN, the drain electrode of described 7th transistor M7 is connected with load load and DC output end mouth DC Output respectively.
Wherein, the first amplifying circuit and the second amplifying circuit constitute two-stage calculation amplifier, for amplifying the feedback signal of output load.And miller compensation electric capacity Cm, then for ensureing the stability of whole linear voltage regulator loop.
Be further used as preferred embodiment, described bias current mirror 11 is PMOS current mirror, and described current mirror load 13 is NMOS current mirror, and described Differential input circuit 12 is PMOS differential pair tube input circuit.
Be further used as preferred embodiment, described the first transistor M1 and transistor seconds M2 is NMOS tube, and described third transistor M3, the 4th transistor M4, the 5th transistor M5, the 6th transistor M6 and the 7th transistor M7 are PMOS.
Below in conjunction with Figure of description and specific embodiment, the present invention is further described in detail.
Embodiment one
With reference to Fig. 4, the first embodiment of the present invention:
AC-DC converter of the present invention is a simple two-port network, and wherein, AC1 and AC2 is input port, and DC Output and GND ground connection output port are output ports.Whole AC-DC converter comprises two major parts: the linear voltage regulator certainly controlling rectifier and high power supply voltage rejection ratio be made up of three grid chi structures.These two parts share an output capacitance, and size only needs 4nF, is easy to integrated on sheet.
Wherein, the core of rectifier is three grid chi structures.Transistor M3 and M5 is the primary path of AC signal from input to output, and the direct current signal primary path on transistor M1 and M2 to be input arrive ground.Transistor M4 and M6 is the switch for realizing from controlling, to avoid producing by MUX the operating path that external pulse signal controls rectifier as rectigulator structure.
The course of work of the whole circuit of the present invention is as follows:
Within a half period, when output voltage higher than DC output end mouth of the voltage of input AC1, M3 opens, and electric current arrives DC output end from M3 through LLDO, M2 also opens by the electric current of ground to AC1 simultaneously, and M5 then turns off to avoid DC output end to arrive the reverse leakage current on ground.Now, M4 turns off, and M1 also turns off, and its signal primary path is as shown in the dotted line in Fig. 4 and arrow, and transducer mainly utilizes LLDO to carry out voltage stabilizing.The direct voltage that this state down-converter exports is
, wherein, Vref is reference voltage, R1 and R2 is the divider resistance of transducer.And when AC1 is less than the signal of output, M3 turns off, main signal path turns off, and now, LLDO does not work, and M2 also turns off.Because the transient response of LLDO is very fast, so its turn-off time is very short, so can effectively avoid reverse leakage to flow through.Now, M4 opens, and voltage stabilizing is realized by the discharge and recharge of DC output end storage capacitance; M1 also opens, thus realizes the circuit alternation of the right and left.And the course of work of input AC2 and the input AC1 course of work similar.
In order to provide the conversion efficiency of transducer further, the present invention also needs the LDO that output capacitance is little, transient response is high, power supply ripple rejection ability is strong.Fig. 5 is the physical circuit schematic diagram of LDO of the present invention.The present invention adopts a PMOS Differential Input, and the two-stage calculation amplifier (first order amplifying circuit and second level amplifying circuit) that N manages active amplification amplifies the feedback signal of load.Wherein, first order amplifying circuit amplifies for the common source of Differential Input pipe, and load current mirror 13 is as its load; Second level amplifying circuit (high-gain stage) is the main circuit improving gain, wherein Current amplifier current mirror 22 improves 10 times the output current of the second level, thus improves mutual conductance, reduces output impedance, add bandwidth, such output stage also can improve the amplitude of oscillation of output voltage.Feedover diode and high pass filter of the present invention forms feedforward path altogether, power supply ripple is fed forward to the grid of transistor M7.The PMOSFET that diode connects is mainly used in the low-frequency ripple that feedovers, and high pass filter is mainly used in feedforward medium-high frequency ripple, and these two signals superpose at the grid place of transistor M7.This feedforward path, improves the Power supply rejection ability of Mid Frequency, reduces output ripple.In addition, the present invention additionally uses the miller compensation electric capacity Cm of a 1pF to ensure the stability of whole loop.
The present invention proposes a kind of new AC-DC converting circuit structure, with rectigulator structure thought similarly, be all that rectifier and pressurizer are combined, to save the bulky capacitor after rectifier.But with rectigulator structure unlike, the mode that present invention employs three grids intersection (cross-gate) Structural Self-Controls is avoided using MUX, solve the reverse leakage flow problem of active diode structure, the method that the metal-oxide-semiconductor be simultaneously connected with diode by high pass filter works in coordination with feedforward improves the Power supply rejection ability of LDO, reduces output ripple.AC-DC converter of the present invention, is applicable to the radio source transmission system of low cost, simple and practical, is easy to integrated and performance is higher, is particularly suitable for using with biologic medical implant devices.
More than that better enforcement of the present invention is illustrated, but the invention is not limited to described embodiment, those of ordinary skill in the art also can make all equivalent variations or replacement under the prerequisite without prejudice to spirit of the present invention, and these equivalent distortion or replacement are all included in the application's claim limited range.