CN106057129A - AMOLED display driving circuit and driving method thereof - Google Patents

Abstract

The invention provides an AMOLED display driving circuit and a driving method thereof. The AMOLED display driving circuit comprises a current digital-to-analog conversion circuit. The current digital-to-analog conversion circuit is used for receiving digital signals and converting the digital signals into voltage signals, then converting the voltage signals into current signals corresponding to the digital signals and inputting the current signals to a current AMOLED pixel circuit as data signals so as to drive an AMOLED pixel array to emit light. The AMOLED display driving circuit and the driving method thereof are used for solving the problems in the prior art that a current steering digital-to-analog conversion circuit DAC is complex in structure and is high in matching difficulty.

Description

AMOLED display driving circuit and driving method thereof

Technical Field

The invention relates to the technical field of flat panel display, in particular to an AMOLED display driving circuit and a driving method thereof.

Background

In recent years, AMOLED (Active-matrix organic light-emitting diode) is increasingly used in mobile phones, tablet computers and other devices because of its advantages of ultra-thin, wide viewing angle, low power consumption, fast response speed, vivid color and the like compared with other display technologies. The AMOLED driving chip mainly comprises a row driving circuit, a column driving circuit, a power supply module, a time sequence and control module and the like, wherein the column driving circuit is a part for converting an input digital image signal into an analog signal corresponding to a gray value to drive AMOLED pixels to emit light, so that the column driving circuit has very important influence on display performance (such as resolution, uniformity, speed and the like).

The AMOLED driving method mainly includes current driving, voltage driving, and digital driving, wherein the voltage driving is currently the most common driving method. Similar to the AMLCD display driving technology, the voltage type driving is widely applied to AMOLED display driving, the voltage type driving can compensate the threshold voltage drift effect of thin film transistor TFTs by carefully designing AMOLED pixels, but the voltage type driving cannot well compensate the mobility change and the non-ideal effect such as IR drop in the pixels, and for the voltage type driving chip, because the nonlinear relation between the input voltage and the current flowing through the AMOLED pixels, Gamma correction is required in the digital-to-analog conversion, so that the circuit structure is further complicated. The threshold voltage drift of TFTs in digital driving is negligible and does not need to be compensated for within a pixel, but digital driving needs to operate at a very high clock frequency, which results in increased power consumption of the driver chip.

The current-mode driving is the most suitable driving mode for AMOLED display driving, and can effectively solve the non-ideal factors such as threshold voltage drift, mobility change, IR drop and the like. In a conventional current-type AMOLED column driving chip, a Digital-to-Analog Converter (DAC) is required to convert an input Digital signal into a corresponding current value, and the current is input to a pixel as a data signal to drive the pixel to emit light. A current steering digital-to-analog conversion circuit DAC is a current steering digital-to-analog conversion circuit DAC, and as shown in fig. 1, the current steering digital-to-analog conversion circuit DAC is a 10-bit binary coding current steering digital-to-analog conversion circuit DAC, where the digital-to-analog conversion circuit DAC is composed of a plurality of current sources, the number of the current sources is the same as the resolution, and in the digital-to-analog conversion circuit DAC, each sub-circuit current is a binary multiple of a reference current, and the whole circuit is very simple, but the largest problem of the structure is that a large glitch is generated during the middle code conversion, and the problem can be solved by converting the coding mode of the current steering digital-to-analog conversion circuit DAC, such as thermometer coding current steering, segmented current steering, and the like, but the. More importantly, the current steering digital-to-analog conversion circuit DAC cannot realize accurate current source matching, so that errors are generated in digital-to-analog conversion, and due to thousands of digital-to-analog conversion circuit DAC channels in the AMOLED column driving chip, non-uniformity among the channels is increased due to mismatching of the current sources, and further the display effect is reduced.

In summary, the current mode driving method is the most suitable driving method for AMOLED display, but the current steering digital-to-analog conversion circuit DAC adopted in the conventional current mode driving chip has the disadvantages of complex structure, high difficulty in matching degree, and the like, so that a novel conversion circuit needs to be provided to overcome the disadvantages of the prior art.

Disclosure of Invention

In view of the above drawbacks of the prior art, an object of the present invention is to provide an AMOLED display driving circuit and a driving method thereof, which are used to solve the problems of complicated structure, difficult matching degree, and the like of the current steering type digital-to-analog conversion circuit DAC in the prior art.

To achieve the above and other related objects, the present invention provides an AMOLED display driving circuit, comprising: the current type digital-to-analog conversion circuit is used for receiving a digital signal, converting the digital signal into a voltage signal, converting the voltage signal into a current signal corresponding to the digital signal, and inputting the current signal into the AMOLED current type pixel circuit as a data signal so as to drive the AMOLED pixel array to emit light.

Preferably, the current-mode digital-to-analog conversion circuit comprises a voltage-mode digital-to-analog conversion circuit, a voltage-current conversion circuit and a current mirror circuit; the voltage type digital-to-analog conversion circuit is used for receiving a digital signal and converting the digital signal into an output voltage signal of the voltage type digital-to-analog conversion circuit; the voltage-current conversion circuit is connected with the output end of the voltage-type digital-to-analog conversion circuit and is used for converting the received output voltage signal of the voltage-type digital-to-analog conversion circuit into a current signal; the current mirror circuit is connected with the output end of the voltage-current conversion circuit and used for receiving the current signal and mirroring to form a mirror current signal, and the mirror current signal is input to the current type pixel circuit as a data signal to drive the AMOLED pixel array to emit light.

Preferably, the current source digital-to-analog conversion circuit further comprises a bias circuit for providing a reference voltage or/and a reference current for the current source digital-to-analog conversion circuit.

Preferably, the voltage type digital-to-analog conversion circuit is a cyclic digital-to-analog conversion circuit or a resistor string digital-to-analog conversion circuit.

Preferably, the voltage-current conversion circuit includes a first transistor and a second transistor, and a drain terminal of the first transistor, a gate terminal of the second transistor, and a drain terminal of the second transistor are commonly connected to an output terminal of the voltage-type digital-to-analog conversion circuit; the source end of the first transistor and the source end of the second transistor are connected with the input end of the current mirror circuit together; and the grid end of the first transistor is connected with grid voltage.

Preferably, the gate voltage of the first transistor is regulated so that the first transistor always operates in a linear region and the second transistor always operates in a saturation region.

Preferably, the current mirror circuit includes a third transistor and a fourth transistor, and a drain terminal and a gate terminal of the third transistor are commonly connected to the output terminal of the voltage-to-current conversion circuit; a gate terminal of the fourth transistor is connected to a gate terminal of the third transistor, and a drain terminal of the fourth transistor is connected to an input terminal of the current-mode pixel circuit and serves as an output terminal of the current-mode digital-to-analog conversion circuit; and the source ends of the third transistor and the fourth transistor are grounded.

Preferably, the AMOLED current type pixel circuit is an AMOLED current type pixel circuit of a 5T1C structure or a 4T2C structure.

Preferably, the expression of the current signal input as the data signal into the current type pixel circuit is:

$I_{OUT}={\mathrm{mV}}_A+n=m(\frac{V_{REFH}-V_{REFL}}{2^n}\underset{i=0}{\overset{n-1}{\Σ}}{2}^i{b}_i+V_{REFL})+n$

wherein m and n are constants, V_AIs the output voltage, V, of a voltage-type digital-to-analog converter_REFHAnd V_REFLThe reference levels are respectively a high reference level and a low reference level of the voltage type digital-to-analog conversion circuit DAC, and bi is a digital signal.

The invention also comprises a driving method of the AMOLED display driving circuit, which comprises the following steps: the method comprises the steps of receiving a digital signal, converting the digital signal into a voltage signal, converting the voltage signal into a current signal corresponding to the digital signal, and inputting the current signal serving as a data signal into an AMOLED current type pixel circuit to drive an AMOLED pixel array to emit light.

Preferably, the current signal is received and mirrored to form a mirror current signal, and the mirror current signal is input to the current type pixel circuit as a data signal to drive the AMOLED pixel array to emit light.

Preferably, the expression of the current signal input as the data signal into the current type pixel circuit is:

$I_{OUT}={\mathrm{mV}}_A+n=m(\frac{V_{REFH}-V_{REFL}}{2^n}\underset{i=0}{\overset{n-1}{\Σ}}{2}^i{b}_i+V_{REFL})+n$

wherein m and n are constants, V_AIs the output voltage, V, of a voltage-type digital-to-analog converter_REFHAnd V_REFLThe reference levels are respectively a high reference level and a low reference level of the voltage type digital-to-analog conversion circuit DAC, and bi is a digital signal.

As described above, the AMOLED display driving circuit and the driving method thereof according to the present invention have the following advantages:

the invention adopts a current type driving mode, and the digital-to-analog conversion process in the circuit is as follows: the voltage-type digital-to-analog conversion circuit DAC can adopt a linear digital-to-analog conversion circuit DAC with a small area, and the voltage/current conversion circuit is completed by skillfully utilizing the complementary characteristics of voltage and current curves of transistors in different working states. The driving circuit not only keeps the advantages that current type driving can effectively solve non-ideal factors such as threshold voltage drift, mobility change, IR drop and the like, but also has the characteristics of simple structure, low power consumption and the like.

Drawings

Fig. 1 shows a conventional 10-bit binary coded current steering dac according to the present invention (prior art).

Fig. 2 is a schematic diagram of the AMOLED display driving circuit according to the present invention.

FIG. 3 shows the voltage V at point A obtained by simulation of the present invention_AAnd I_C1、I_C2And I_OUTSchematic diagram of the relationship of (1).

Description of the element reference numerals

Eighth transistor of 1-current type digital-to-analog conversion circuit MP4

2-current type pixel circuit V_AVoltage at point A

101 n bit voltage type DAC V_BGGate terminal voltage of the first transistor

102 voltage-current conversion circuit b_n-1-b₀Input digital signal of n-bit current type DAC

103 current mirror circuit I_OUTOutput current of current mode DAC

104 bias circuit V_REFHHigh reference level for n-bit voltage-mode DAC

M_C1A first transistor V_REFLLow reference level for n-bit voltage-mode DAC

M_C2Second transistor C_sCapacitor with a capacitor element

M_CM1Third transistor OLED organic light emitting diode

M_CM2Fourth transistor Select [ m ]]A first control signal

Second control signal of fifth transistor Emit [ m ] of MP1

Power signal line of MP2 sixth transistor ELVDD pixel array

Ground signal line of MP3 seventh transistor ELVSS pixel array

I_C1Flows through M_C1Current of drain terminal I_C2Flows through M_C2Current of drain terminal

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Please refer to fig. 2 to fig. 3. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

As shown in fig. 2, the present invention provides an AMOLED display driving circuit, including: the current type digital-to-analog conversion circuit DAC is used for receiving digital signals, converting the digital signals into voltage signals, converting the voltage signals into current signals corresponding to the digital signals, and inputting the current signals into the AMOLED current type pixel circuit as data signals so as to drive the AMOLED pixel array to emit light.

Specifically, the AMOLED display driving circuit includes an n-bit current type digital-to-analog conversion circuit DAC and an AMOLED current type pixel circuit, as an example. The n-bit current type digital-to-analog conversion circuit DAC comprises an n-bit voltage type digital-to-analog conversion circuit DAC, a voltage current conversion circuit, a current mirror circuit and a bias circuit. The n-bit voltage type digital-to-analog conversion circuit DAC is used for receiving a digital signal and converting the digital signal into an output voltage signal of the n-bit voltage type digital-to-analog conversion circuit DAC; the voltage-current conversion circuit is connected with the output end of the voltage-type digital-to-analog conversion circuit DAC and is used for converting the received output voltage signal of the n-bit voltage-type digital-to-analog conversion circuit DAC into an input current signal of the current mirror circuit; the current mirror circuit is connected with the output end of the voltage-current conversion circuit and used for receiving the input current signal, carrying out mirror conversion on the input current signal to form a mirror current signal, and taking the output mirror current signal of the current mirror circuit as the output current of the current type digital-to-analog conversion circuit DACSignal I_OUTThe output current signal I of the current type digital-to-analog conversion circuit DAC is used_OUTThe data signals are input to the AMOLED current type pixel circuit. The AMOLED display driving circuit further comprises a bias circuit which provides reference voltage or reference current for the current type digital-to-analog conversion circuit DAC. In this example, the AMOLED display driving circuit is an AMOLED column driving circuit, and the column driving circuit is a portion that converts an input digital image signal into an analog signal corresponding to a gray scale value to drive the AMOLED pixel to emit light, so the column driving circuit has a very important influence on display performance (such as resolution, uniformity, speed, etc.).

Preferably, the n-bit voltage type digital-to-analog conversion circuit DAC is a cyclic digital-to-analog conversion circuit or a resistor string digital-to-analog conversion circuit. Of course, in other embodiments, the current mode pixel circuit may be any type of current mode pixel, and is not limited herein.

Specifically, the voltage-current conversion circuit comprises a first transistor M_C1And a second transistor M_C2The first transistor M_C1Drain terminal of the second transistor M_C2The grid end and the drain end of the N-bit voltage type digital-to-analog conversion circuit are connected with the output end of the DAC; the first transistor M_C1Is connected to the second transistor M_C2And the common terminal of the source terminal of the voltage-current conversion circuit is used as the output terminal of the voltage-current conversion circuit; the first transistor M_C1Is connected to the bias circuit.

Specifically, the current mirror circuit includes a third transistor M_CM1And a fourth transistor M_CM2The drain end of the third transistor is connected with the grid end of the third transistor, and the common end of the third transistor is connected with the output end of the voltage-current conversion circuit; a gate end of the fourth transistor is connected with a gate end of the third transistor, a drain end of the fourth transistor is connected with an input end of the AMOLED current type pixel circuit, and a drain end of the fourth transistor is used as an output end of the DAC of the current type digital-to-analog conversion circuit; and the source ends of the third transistor and the fourth transistor are grounded.

PreferablyThe current type pixel circuit is a current type pixel circuit with a 5T1C structure or a 4T2C structure. Of course, in other embodiments, the current mode pixel circuit may be any type of current mode pixel, and is not limited herein. As an example, as shown in fig. 2, the structure and principle of the AMOLED current type pixel circuit are described as follows: the AMOLED current type pixel circuit comprises four transistors (fifth transistor MP 1-eighth transistor MP4), a capacitor C_sAn organic light emitting diode OLED and two sets of control signals (first control signal Select [ m ]]And a second control signal Emit m]) And (4) forming. Wherein the sixth transistor M_P2The seventh transistor M_P3And an eighth transistor M_P4A switching transistor for switching, a fifth transistor M_P1A drive transistor for providing drive current for OLED, a capacitor Cs for storing M of the fifth transistor_P1The gate voltage of (c). First control signal Select [ m ]]For selecting the control signal, second control signal Emit m]Is a light emission control signal. ELVDD and ELVSS are power supply signal lines and ground signal lines of the pixel array, respectively. The driving time sequence of the AMOLED current type pixel circuit is divided into two stages, namely a programming stage and a light emitting stage, wherein in the programming stage, a first control signal Select [ m ]]At a low level, the second control signal Emit [ m ]]At a high level, the sixth transistor MP2 and the seventh transistor MP3 are turned on, the eighth transistor MP4 is turned off, the gate and the drain of the fifth transistor MP1 are connected together, and the current flowing through the fifth transistor MP1 is the programming current (i.e., the output current I of the current-type DAC circuit)_OUT) And the gate voltage of the fifth transistor MP1 is stored in the lower plate of the capacitor Cs. After the programming phase is finished, the light-emitting phase is entered, and at this time, the first control signal Select [ m ]]Goes high, the second control signal Emit m]When the voltage level is changed to low level, the sixth transistor MP2 and the seventh transistor MP3 are turned off, the eighth transistor MP4 is turned on, and the light emitting current flows from the power signal line ELVSS to the OLED through the fifth transistor MP1, and since the gate of the fifth transistor MP1 has no charge leakage path, the gate-source voltage of the fifth transistor MP1 is equal to the programming voltage during the light emitting period, i.e., the current flowing through the organic light emitting diode OLED during the light emitting period is equal to the programming current.

As shown in fig. 2 to 3, the operation principle of the AMOLED display driving circuit is as follows:

an n-bit digital signal (b) to be inputted to the voltage type DAC circuit_n-1-b₀) Converting the voltage value into an n-bit voltage DAC output terminal and a first transistor M_C1And a second transistor M_C2We denote this point as point a, and the point voltage is denoted as V_A，V_ACan be expressed as:

$V_A=\frac{V_{REFH}-V_{REFL}}{2^n}\underset{i=0}{\overset{n-1}{\Σ}}{2}^i{b}_i+V_{REFL}---\left(1\right)$

wherein, V_REFHAnd V_REFLThe n-bit voltage type DAC has a high reference level and a low reference level, respectively, and bi is an input digital signal.

First transistor M_C1And a second transistor M_C2Constituting a voltage-current conversion circuit, a first transistor M_C1Drain terminal of the second transistor M_C2Gate terminal of and second transistor M_C2The drain terminal of the first transistor M is connected to the point A_C1And a second transistor M_C2Is connected to point B. By reasonably arranging the first transistor M_C1Gate terminal voltage V of_BGMake the first transistor M_C1Always operating in the linear region due to the second transistor M_C2Are connected together, so that the second transistor M_C2Always working in a saturation region. First transistor M_C1And a second transistor M_C2Respectively represented as I_C1And I_C2：

$I_{C1}=K_n{\left(\frac{W}{L}\right)}_1\[(V_{BG}-V_B-V_{THN1})(V_A-V_B)-\frac{{(V_A-V_B)}^2}{2}\]---\left(2\right)$

$I_{C2}=K_n{\left(\frac{W}{L}\right)}_2{(V_A-V_B-V_{THN2})}^2---\left(3\right)$

Wherein,andare respectively a first transistor M_C1And a second transistor M_C2Width to length ratio of V_THN1And V_THN2Are respectively a first transistor M_C1And a second transistor M_C2Herein for simplicity, we consider bothAre equal.

Third transistor M_CM1And a fourth transistor M_CM2Forming a current mirror circuit through the third transistor M_CM1Is caused to flow through the first transistor M_C1And a second transistor M_C2The sum of the drain currents, therefore:

$\begin{array}{c}{I}_{OUT}=I_{CM2}=I_{CM1}=K_n{\left(\frac{W}{L}\right)}_1\[(V_{BG}-V_B-V_{THN1})(V_A-V_B)-\frac{{(V_A-V_B)}^2}{2}\]\\ +K_n{\left(\frac{W}{L}\right)}_2{(V_A-V_B-V_{THN2})}^2\end{array}---\left(4\right)$

will I_OUTTo V_ATaking the derivative, we can get:

$\begin{array}{c}\frac{\∂I_{OUT}}{\∂V_A}=K_n{\left(\frac{W}{L}\right)}_1\[(V_{BG}-V_B-V_{THN1})(1-\frac{\∂V_B}{\∂V_A})-\frac{\∂V_B}{\∂V_A}(V_A-V_B)\]\\ -K_n{\left(\frac{W}{L}\right)}_1(V_A-V_B)(1-\frac{\∂V_B}{\∂V_A})+2K_n{\left(\frac{W}{L}\right)}_2(V_A-V_B-V_{THN2})(1-\frac{\∂V_B}{\∂V_A})\end{array}---\left(5\right)$

at the same time, flows through the third transistor M_CM1The current can also be expressed as:

$I_{CM1}=I_{OUT}=K_n{\left(\frac{W}{L}\right)}_{CM2}{(V_B-V_{THMC2})}^2---\left(6\right)$

thus, it is possible to obtain:

$V_B=\sqrt{\frac{I_{OUT}}{K_n{\left(\frac{W}{L}\right)}_{CM2}}}+V_{THMC2}---\left(7\right)$

the above formula is bilateral pair I_OUTTaking the derivative, we can get:

$\frac{\∂V_B}{\∂I_{OUT}}=\frac{1}{2\sqrt{I_{OUT}{K}_n{\left(\frac{W}{L}\right)}_{CM2}}}---\left(8\right)$

when in useWhen large, it can be considered thatAnd the result obtained by equation (5) is a finite value, it can be found that:

$\frac{\∂V_B}{\∂V_A}=\frac{\∂I_{OUT}}{\∂V_A}\×\frac{\∂V_B}{\∂I_{OUT}}\≈0---\left(9\right)$

equation (5) can therefore be simplified to:

$\frac{\∂I_{OUT}}{\∂V_A}=K_n(2{\left(\frac{W}{L}\right)}_2-{\left(\frac{W}{L}\right)}_1)V_A+K_n{\left(\frac{W}{L}\right)}_1(V_{BG}-V_{THN1})-2K_n{\left(\frac{W}{L}\right)}_2(V_B+V_{THN2})---\left(10\right)$

as a result of this, it is possible to,therefore we consider V_BIs a constant value, therefore, in formula (8)Then, one can obtain:

$\frac{\∂I_{OUT}}{\∂V_A}=K_n{\left(\frac{W}{L}\right)}_1(V_{BG}-V_B-V_{THN1}-V_{THN2})---\left(11\right)$

it can be seen that formula (10) is AND V_AIndependent constant value, order

$K_n{\left(\frac{W}{L}\right)}_1(V_{BG}-V_B-V_{THN1}-V_{THN2})=m---\left(12\right)$

Then there are:

$I_{OUT}={\mathrm{mV}}_A+n=m(\frac{V_{REFH}-V_{REFL}}{2^n}\underset{i=0}{\overset{n-1}{\Σ}}{2}^i{b}_i+V_{REFL})+n---\left(13\right)$

in the formula (12), m and n are constants, and I is shown_OUTAnd voltage V at point A_AIs a linear relationship, and V_AThe output voltage of the voltage type digital-to-analog conversion circuit DAC is obtained, and therefore the linear conversion process from digital signals to current is effectively completed.

In this embodiment, with the circuit structure of the present invention, circuit simulation is performed, and the voltage at the point a in fig. 2 is subjected to dc scanning, so as to obtain the voltages respectively flowing through the first transistor M_C1And a second transistorM_C2Current of drain terminal I_C1And I_C2And the output current I of the current-mode DAC circuit_OUTThe transmission curve of (1). FIG. 3 is a specific curve obtained by simulation, and we can see the output current I_OUTAnd the output A point voltage V of the DAC circuit_ASubstantially linear over a wide range and due to the input digital signal and the voltage V at point A_AIs linear in relation to the voltage V at point A_AAnd an output current I_OUTIs linear, so that the input digital signal and the output current I can be illustrated_OUTAlso a linear relationship. Output current I_OUTInputting the data signal into a current type pixel circuit, programming the pixel, and driving the organic light emitting diode OLED to emit light due to the input of the digital signal and the current I_OUTThe linear relationship is adopted, so that the brightness of the organic light-emitting diode OLED and the input digital signal are also in the linear relationship, and the influence of non-ideal factors such as threshold voltage drift, mobility change, IR drop and the like can be eliminated.

Of course, those skilled in the art can make appropriate changes to the pixel circuit structure and driving method proposed in the present invention, for example, to appropriately change the type (P-type or N-type) of each switching transistor of the pixel circuit, and to interchange the electrical connection relationship between the source and the drain of each transistor.

In summary, the current type digital-to-analog conversion circuit DAC is formed by cascading the voltage type digital-to-analog conversion circuit DAC and the voltage-to-current linear conversion circuit, wherein the voltage type digital-to-analog conversion circuit DAC can adopt the linear digital-to-analog conversion circuit DAC with a smaller area, and the voltage-to-current conversion circuit is completed by ingeniously utilizing the complementary characteristics of the voltage-to-current curves of the transistors in different working states. Compared with the traditional current steering digital-to-analog conversion circuit DAC, the current type digital-to-analog conversion circuit DAC has the advantages of simple structure, low power consumption and the like.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (12)

1. An AMOLED display driving circuit, comprising: the current type digital-to-analog conversion circuit is used for receiving a digital signal, converting the digital signal into a voltage signal, converting the voltage signal into a current signal corresponding to the digital signal, and inputting the current signal into the AMOLED current type pixel circuit as a data signal so as to drive the AMOLED pixel array to emit light.

2. The AMOLED display driver circuit of claim 1, wherein: the current type digital-to-analog conversion circuit comprises a voltage type digital-to-analog conversion circuit, a voltage current conversion circuit and a current mirror circuit;

the voltage type digital-to-analog conversion circuit is used for receiving a digital signal and converting the digital signal into an output voltage signal of the voltage type digital-to-analog conversion circuit;

the voltage-current conversion circuit is connected with the output end of the voltage-type digital-to-analog conversion circuit and is used for converting the received output voltage signal of the voltage-type digital-to-analog conversion circuit into a current signal;

the current mirror circuit is connected with the output end of the voltage-current conversion circuit and used for receiving the current signal and mirroring to form a mirror current signal, and the mirror current signal is input to the current type pixel circuit as a data signal to drive the AMOLED pixel array to emit light.

3. The AMOLED display driver circuit of claim 2, wherein: the current type digital-to-analog conversion circuit further comprises a bias circuit used for providing reference voltage or/and reference current for the current type digital-to-analog conversion circuit.

4. The AMOLED display driver circuit of claim 2, wherein: the voltage type digital-to-analog conversion circuit is a circulating digital-to-analog conversion circuit or a resistor string digital-to-analog conversion circuit.

5. The AMOLED display driver circuit of claim 2, wherein: the voltage-current conversion circuit comprises a first transistor and a second transistor, and the drain terminal of the first transistor, the gate terminal of the second transistor and the drain terminal of the second transistor are connected with the output end of the voltage-type digital-to-analog conversion circuit; the source end of the first transistor is connected with the source end of the second transistor, and the common end of the first transistor is used as the output end of the voltage-current conversion circuit; and the grid end of the first transistor is connected with grid voltage.

6. The AMOLED display driving circuit of claim 5, wherein: the gate voltage of the first transistor is regulated, so that the first transistor always works in a linear region, and the second transistor always works in a saturated region.

7. The AMOLED display driver circuit of claim 2, wherein: the current mirror circuit comprises a third transistor and a fourth transistor, wherein the drain end of the third transistor is connected with the gate end of the third transistor, and the common end of the third transistor is connected with the output end of the voltage-current conversion circuit; a gate end of the fourth transistor is connected with a gate end of the third transistor, a drain end of the fourth transistor is connected with an input end of the current type pixel circuit, and a drain end of the fourth transistor is used as an output end of the current type digital-to-analog conversion circuit; and the source ends of the third transistor and the fourth transistor are grounded.

8. The AMOLED display driver circuit of claim 1, wherein: the AMOLED current type pixel circuit is an AMOLED current type pixel circuit with a 5T1C structure or a 4T2C structure.

9. The AMOLED display driving circuit of any one of claims 1-8, wherein: the expression of the current signal input as a data signal into the current-type pixel circuit is:

$I_{OUT}={\mathrm{mV}}_A+n=m(\frac{V_{REFH}-V_{REFL}}{2^n}\underset{i=0}{\overset{n-1}{\Σ}}{2}^i{b}_i+V_{REFL})+n$

wherein m and n are constants, V_AIs the output voltage, V, of a voltage-type digital-to-analog converter_REFHAnd V_REFLThe reference levels are the high reference level and the low reference level of the voltage type digital-to-analog conversion circuit, and bi is a digital signal.

10. A driving method of an AMOLED display driving circuit is characterized by comprising the following steps:

the method comprises the steps of receiving a digital signal, converting the digital signal into a voltage signal, converting the voltage signal into a current signal corresponding to the digital signal, and inputting the current signal serving as a data signal into an AMOLED current type pixel circuit to drive an AMOLED pixel array to emit light.

11. The driving method of the AMOLED display driving circuit of claim 10, wherein:

receiving a digital signal, converting the digital signal into a voltage signal, converting the voltage signal into a current signal corresponding to the digital signal, receiving the current signal and mirroring to form a mirror current signal, and inputting the mirror current signal into a current type pixel circuit as a data signal to drive the AMOLED pixel array to emit light.

12. The driving method of the AMOLED display driving circuit of claim 10 or 11, wherein: the expression of the current signal input as a data signal into the current-type pixel circuit is:

$I_{OUT}={\mathrm{mV}}_A+n=m(\frac{V_{REFH}-V_{REFL}}{2^n}\underset{i=0}{\overset{n-1}{\Σ}}{2}^i{b}_i+V_{REFL})+n$

wherein m and n are constants, V_AIs the output voltage, V, of a voltage-type digital-to-analog converter_REFHAnd V_REFLThe reference levels are the high reference level and the low reference level of the voltage type digital-to-analog conversion circuit, and bi is a digital signal.