A kind of linear voltage regulator of wideband high PSRR
Technical field
The invention belongs to high performance analog IC design technical fields, and in particular to a kind of wideband high PSRR
Linear voltage regulator.
Background technique
Low pressure difference linear voltage regulator (LDO), since simple with circuit structure, transient response speed is fast, at low cost etc. excellent
Point is used widely.The DC high voltage of input can be converted to low line needed for electronic equipment by low pressure difference linear voltage regulator
The DC low-voltage of wave, low noise.Under normal circumstances, on the input direct-current voltage of low pressure difference linear voltage regulator, broadband can be superimposed
AC ripple, will affect the stability and circuit performance of equipment and circuit.When needing high-performance power supply, nonideal group
Part and parasitic capacitance can change the ideal characterisitics of linear voltage regulator, reduce the inhibiting effect to mains fluctuations.Power supply inhibits
What is measured than this index is that voltage-stablizer inhibits the ability of AC signal being superimposed upon on normal input direct-current voltage.Power supply inhibits
It is more maximum than in low frequency, inhibit the ability of mains fluctuations stronger, and in high frequency, this ability just reduces.It is practical low
The design of pressure difference linear voltage regulator, power supply rejection ratio are begun to decline in range from 1kHz to 10kHz.
The raising of requirement with user to power supply ripple rejection ability, low noise, high PSRR linear voltage regulator
It is required that it is in the good power supply rejection ratio still in 100kHz with 60dB.In 100kHz or more, power supply rejection ratio mainly by
The influence of upper leakage current is managed in output capacitance, parasitic element and adjustment.
Power supply rejection ratio is the Key Performance Indicator of linear voltage regulator, and power supply rejection ratio is often depending on the essence of band-gap reference
The open-loop gain of degree and linear voltage regulator error amplifier circuit.Under normal conditions, linear voltage regulator is higher in order to obtain
Power supply rejection ratio, just using biggish error signal amplification open-loop gain, or increase output end coupled capacitor, drop
The bandwidth of low linear voltage regulator.Open-loop gain is amplified using biggish error, biggish challenge can be brought to circuit design.And increase
The mode of big output end coupled capacitor, and will increase the area of chip, increase production cost.
Summary of the invention
According to the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to propose a kind of high power supply suppression of wideband
The linear voltage regulator of ratio processed has wideband high PSRR characteristic, influences the spies such as small, current efficiency is high to system stability
Point.
In order to solve the above-mentioned technical problem, a kind of the technical solution adopted by the present invention are as follows: line of wideband high PSRR
Property voltage-stablizer, which is characterized in that the linear voltage regulator includes power supply ripple preprocessor and low pressure difference linear voltage regulator LDO;Institute
The output of power supply ripple preprocessor is stated to be connected with low-dropout regulator LDO input power;The power supply ripple preprocessor is used for
Generate the DC voltage VP1 of wideband Ripple Suppression;The low pressure difference linear voltage regulator LDO is for generating DC output voltage
VOUT;The power-supply ripple preprocessor includes resistor voltage divider circuit, low-pass filter and voltage follower;The electric resistance partial pressure
Circuit, low-pass filter, voltage follower are sequentially connected;The resitstance voltage divider generates one by resistor voltage divider circuit and is lower than
The reference voltage VR1 of supply voltage;The low-pass filter is used to filter out the power supply disturbance and noise on VR1, obtains ripple suppression
Voltage VG1 processed;The voltage follower is used to generate the DC voltage VP1 of Ripple Suppression.The resistor voltage divider circuit is by dividing
Pressure obtains the reference voltage VR1 for being slightly below supply voltage.The resistor voltage divider circuit is series resistance bleeder circuit.
The voltage follower is to connect into power supply buffer stage, line using depletion mode transistor M1, depletion mode transistor M1
Wave inhibits voltage VG1 to send to the grid of depletion mode transistor M1, the source electrode of M1 obtain close to Ripple Suppression voltage VG1 with
With voltage VP1.
The low pressure difference linear voltage regulator LDO includes band-gap reference circuit VBG, error amplifier AMP, adjustment pipe, feedback
Resistor network, output coupling capacitor and bias current adjustment circuit IBIAS;The band-gap reference circuit VBG, bias current adjustment
Circuit I BIAS is connected with error amplifier AMP respectively.
The band-gap reference circuit VBG provides reference voltage VREF for low pressure difference linear voltage regulator;Biased electrical miscarriage
The size of raw circuit I BIAS control reference current IB;The difference of reference voltage VREF and feedback voltage V FB are by amplification
Afterwards, it is connected to the grid of adjustment pipe M2, output voltage VO UT is controlled;Resistance R5 and R6 constitute feedback network, will divide
VFB feeds back to the positive polarity input terminal of error amplifier AMP.
Since the DC voltage VP1 by Ripple Suppression reduces the input power fluctuation of low pressure difference linear voltage regulator LDO,
Obtain the DC output voltage VOUT of wideband high PSRR.
The medicine have the advantages that the electricity constituted by using stable Ripple Suppression voltage VG1 and depletion mode transistor
Buffer stage is pressed, the DC voltage VP1 of relatively stable wideband Ripple Suppression can be obtained, reduce low pressure difference linear voltage regulator
The ripple of LDO input power.Power input of the output of voltage buffer grade as low pressure difference linear voltage regulator, finally obtaining has
The output voltage VO UT of wideband high PSRR, improves the precision of electrical equipment.There is the present invention the high PSRR of wideband to load model
It encloses, the features such as small, current efficiency is high is influenced on system stability.
Detailed description of the invention
Content expressed by this specification attached drawing and the label in figure are briefly described below:
Fig. 1 is the linear voltage regulator system construction drawing of the wideband high PSRR of a specific embodiment of the invention.
Fig. 2 is the schematic diagram of the wideband high PSRR linear voltage-stabilizing circuit of a specific embodiment of the invention.
Specific embodiment
Below against attached drawing, by the description of the embodiment, for example related each component of a specific embodiment of the invention
Shape, construction, the mutual alignment between each section and connection relationship, the effect of each section and working principle, manufacturing process and
Operate with method etc., is described in further detail, to help those skilled in the art to inventive concept of the invention, technology
Scheme has more complete, accurate and deep understanding.
The invention discloses a kind of linear voltage regulator with wideband high PSRR, using the structure of two-stage pressure stabilizing,
To obtain wideband high PSRR characteristic.Its complete circuit is steady by primary power source ripple preprocessor and level-one low pressure difference linearity
Depressor composition.Wherein, power supply ripple preprocessor is composed in series by resistor voltage divider circuit, low-pass filter, voltage follower.It is logical
Cross resistor voltage divider circuit and generate the reference voltage VR1 for being lower than supply voltage, by low-pass filter, filter out power supply disturbance and
Noise obtains having compared with high stability Ripple Suppression voltage VG1.The direct current close with VG1 numerical value is obtained by voltage follower
Voltage VP1, VP1 eventually as low pressure difference linear voltage regulator power supply, low pressure difference linear voltage regulator by loop control, be
Load provides stable voltage output VOUT, to realize wideband Ripple Suppression.Technical solution is referring to Fig. 1.
As shown in Fig. 2, in order to make linear voltage regulator obtain high PSRR, using the pretreatment skill of power supply ripple
Art.Wherein, first order power supply ripple preprocessor is made of resistor voltage divider circuit, low-pass filter and voltage follower.Second
Grade is a low pressure difference linear voltage regulator LDO.Wherein, low pressure difference linear voltage regulator LDO include again band-gap reference circuit (VBG),
Error amplifier (AMP), adjustment pipe, feedback resistive network, output coupling capacitor, bias current adjustment circuit (IBIAS) composition.
In first order power supply ripple preprocessor, pass through the bleeder circuit and low-pass filter being made of resistance R1 and R2
LPF obtains a relatively stable d. c. voltage signal VG1.One is generated using the resistor voltage divider circuit of resistance R1 and R2 composition
A reference voltage VR1 lower than supply voltage can also be provided this reference voltage VR1 by other kinds of circuit.Benchmark electricity
It presses VR1 using low-pass filter, realizes filtering out for high-frequency noise, obtain stable Ripple Suppression voltage VG1.Ripple Suppression electricity
VG1 is pressed to be lower than power source supplying voltage, voltage value is determined by the payload size of voltage regulator circuit.Depletion mode transistor M1 is connected into
Power supply buffer stage, Ripple Suppression voltage VG1 are sent to the grid of depletion mode transistor M1, available close to line in the source electrode of M1
Wave inhibits the more stable of voltage VG1 to follow voltage VP1, and power input of the VP1 as low-dropout linear voltage-regulating circuit LDO has
There is lesser power supply ripple.
Band-gap reference circuit VBG provides the reference voltage VREF of a 1.2V for low pressure difference linear voltage regulator.Biasing
Current generating circuit IBIAS can control the size of reference current IB, and then control the static function of error amplifier AMP work
Consumption.Resistance R3 and R4 constitute feedback network, and partial pressure VFB is fed back to the positive polarity input terminal of error amplifier AMP.Reference
The difference of voltage VREF and feedback voltage V FB are connected to the grid of adjustment pipe M2 after amplification, carry out to output voltage VO UT
Control.Since the DC voltage VP1 by Ripple Suppression reduces the input power fluctuation of low pressure difference linear voltage regulator LDO, most
The DC output voltage VOUT of wideband high PSRR can be obtained eventually.It is negative to make linear voltage regulator of the invention be supplied to
The output voltage of load has the characteristic of the high Ripple Suppression of wideband.
The present invention is exemplarily described above in conjunction with attached drawing, it is clear that the present invention implements not by aforesaid way
Limitation, as long as the improvement for the various unsubstantialities that the inventive concept and technical scheme of the present invention carry out is used, or without changing
It is within the scope of the present invention into the conception and technical scheme of the invention are directly applied to other occasions.This hair
Bright protection scope should be determined by the scope of protection defined in the claims.