CN100546195C - A kind of improved voltage marking D/A converter - Google Patents
A kind of improved voltage marking D/A converter Download PDFInfo
- Publication number
- CN100546195C CN100546195C CNB2007101345023A CN200710134502A CN100546195C CN 100546195 C CN100546195 C CN 100546195C CN B2007101345023 A CNB2007101345023 A CN B2007101345023A CN 200710134502 A CN200710134502 A CN 200710134502A CN 100546195 C CN100546195 C CN 100546195C
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- China
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- voltage
- network
- fine tuning
- resistor network
- operational amplifier
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Abstract
The present invention relates to a kind of circuit, refer in particular to a kind of improved voltage marking D/A converter, be mainly used in audio systems such as USB (USB) earphone, Mike and phone.According to technical scheme provided by the invention, in a string and combined resistance network, voltage is divided into roughly adjusted rheostat network and two parts of fine tuning resistor network, and be connected with the operational amplifier positive terminal at the output of roughly adjusted rheostat network, the output of fine tuning resistor network is connected with the negative phase end of operational amplifier, have the quantification diverter switch respectively on each resistance on roughly adjusted rheostat network and the fine tuning resistor network, correction resistance is connected in parallel on the fine tuning resistor network; During work, import binary data to be converted earlier, and these data are divided into a high position and low level, wherein low level goes to control the quantification diverter switch of fine tuning resistor network after decoding.The present invention reduces the cost of product by reducing the quantity of resistance, improves the conversion accuracy of product.
Description
Technical field
The present invention relates to a kind of circuit, refer in particular to a kind of improved voltage marking D/A converter, be mainly used in audio systems such as USB (USB) earphone, Mike and phone.
Background technology
Traditional simple and easy voltage marking digital-to-analogue conversion (DAC) is by utilizing 2
nThe resistance string that individual resistance is formed is with V
RefBe divided into equal 2
nSection as shown in Figure 2, thereby realizes intrinsic monotonicity.Every group of binary switch tree is selected corresponding to given input data bit.Its another advantage is if the magnitude of voltage V that the top node of resistance string is connected with bottom node
hAnd V
lBe an arbitrary value, then DAC will be at V
hAnd V
lBetween with having 2
nThe resolution of individual quantification step is carried out interpolation.But maximum resistance number (2
n) and switch number (2
N+1-2) the potential measurement DAC of reality is limited in the scope of n≤8, the area that mainly is subject to resistance is too big, and the relative accuracy of resistance effective performance wayward and electronic switch does not reach designing requirement.Thereby influenced the conversion accuracy of DAC.
Summary of the invention
The objective of the invention is to seek a kind of improved voltage marking D/A converter,, reduce the cost of product, improve the conversion accuracy of product by reducing the quantity of resistance.
According to technical scheme provided by the invention, in a string and combined resistance network, voltage is divided into roughly adjusted rheostat network and two parts of fine tuning resistor network, and be connected with the operational amplifier positive terminal at the output of roughly adjusted rheostat network, the output of fine tuning resistor network is connected with the negative phase end of operational amplifier, have the quantification diverter switch respectively on each resistance on roughly adjusted rheostat network and the fine tuning resistor network, correction resistance is connected in parallel on the fine tuning resistor network; During work, import binary data to be converted earlier, and these data are divided into a high position and low level, wherein low level goes to control the quantification diverter switch of fine tuning resistor network after decoding; Go to control the quantification diverter switch of roughly adjusted rheostat network after the high-order decoding, after quantizing, take out the positive terminal that a voltage is given operational amplifier from the roughly adjusted rheostat network, the fine tuning resistor network takes out the negative phase end that a voltage is given operational amplifier, through computing, draw the voltage after the conversion.
Utilize operational amplifier to carry out computing when computing, operational formula is: U
O=2U
M-U
N, U wherein
MCoarse tuning voltage after referring to quantize, U
NFine tuning voltage after referring to quantize, U
oOutput voltage after referring to change.The output of fine tuning resistor network is connected with the negative phase end of operational amplifier after through a follower; The fine tuning resistor network takes out a voltage is given operational amplifier behind follower negative phase end.Wherein decoding again after the negate of low level elder generation.
After applying the present invention to USB voice control chip, can better improve Audio Processing speed.Therefore compare with traditional voltage marking DAC, needed resistance number is few, analog switch is few, has advantages such as precision height, speed are fast, monotonicity.The DAC of traditional voltage marking 16bit needs 2
16(about 6.6 ten thousand) individual resistance.Because multicore sheet area is big more for the high more needed resistance of precision, be not easy to relative accuracy control, electronic switch quantity is many, and the cost price of product is too high.So on performance and cost, be difficult to accomplish the high accuracy DAC of 16bit.And this project adopted is modified model voltage marking DAC, and the resistance number and the analog switch that are adopted significantly reduce.
Description of drawings
Fig. 1 is the system diagram that applies the present invention to the USB audio control chip.
Fig. 2 is traditional voltage marking digital-to-analogue conversion figure.
Fig. 3 is voltage marking digital-to-analogue conversion figure of the present invention.
Fig. 4 is 16 DAC resistor network schematic diagrames.
Fig. 5 is the computing circuit that takes out voltage.
Embodiment
Mentality of designing of the present invention is: utilize in the CMOS technology, the advantage that the relative accuracy of device can accurately be controlled, a string and combined resistance network have been designed, voltage is divided into roughly adjusted rheostat networking and two parts of fine tuning resistor network, cooperates 1 operational amplifier to realize high-precision 16 figure place weighted-voltage D/A converters at last.Employed resistance number only is 2
9+ 2
7Individual, add 37 in addition and revise resistor network (as shown in Figure 4).Adopt 0.35um CMOS 3.3V/5V technology, polysilicon is done resistance, and the electric resistance array layout structure has effectively dwindled area through ingenious design, and relative accuracy is controlled easily like this, is convenient to integrated.
Under the load of 10k ohm, THD+N (3dB) is-74.29dB, the processing signals bandwidth is 20kHz, SNR is 93.6dB, and silent SNR can reach 98.2dB.1LSB can reach 34uV, and it is 1.25Vrms that Dynamic Range can reach 93.8dB.Output Vltage (rms), Output Vltage Swing is that 0.5v is to 4v, conversion speed is fast, and the precision height has advantages such as monotonicity.And the foundation of signal and sampling cooperate response fast and high sensitivity operational amplifier to be able to quick conversion.What the reference voltage of amplifier adopted is the high accuracy band-gap reference with temperature-compensating.V
RefFor 2.25V. guarantees that reference voltage is not subjected to power supply and Temperature Influence, thereby guarantee the precision of DAC.The changing voltage formula
D in the formula
15D
14... D
0Be the 16 bit data input of DA, Uc is the DA bias voltage, R
bIt is according to the value of Uc and fixed biasing resistor.
The effect of Uc: owing to will in resistor network, extract different voltage out, and minimum voltage is very little again, the transmission of voltage is to adopt the NMOS of switching mode to finish, because transmission voltage has the threshold value loss, therefore be necessary for adopt voltage provide a dc offset voltage to come the bucking voltage loss, guarantee the precision of sampled voltage.And for the amplifier of back provides biasing.Its voltage swing with output is relevant simultaneously, so the design tradeoff value is the Vt+Vo value of NMOS.
Operation principle is as follows
Can obtain from Fig. 4:
So the electric current of entire circuit is: I
d=V
Ref/ [(2
9+ 1+2) R+R
b] ... 2
U
c=I
d*R
b
Obtain U by 1 and 2
Bc=I
d* R
Bc=I
d* 2R=2*U
m... 3
R
BcRefer to the resistance that the b point is ordered to c among Fig. 4,
U
mRefer to the pressure drop of a resistance on the roughly adjusted rheostat network, 2
9An ohmically dividing potential drop size is I in the resistor network
d* R ... 4
U
nBe 2
7Ohmically dividing potential drop size in the resistor network gets by 1 and 3:
U
n=U
bc/2
7=2U
m/2
7=2U
m/2
6......5
That is: U
m=2
6U
n
Fig. 5 is the computing circuit that takes out voltage.
The output voltage of DAC is by 2
9Resistor network and 2
7Resistor network is respectively got a voltage and is obtained through computing:
U
M=U
m*(D
15~D
7+1)+U
bc+U
C
U
N=U
n*(D
6~D
0)+U
C
We can obtain U by computing circuit
O=2U
M-U
N
U
O=2[U
m(D
15~D
7+1)+U
bc+U
C]-U
n(D
6~D
0)+U
C
Solve
If
That is: U
O=LSB*[2
7(D
15~D
7+ 1)-(D
6~D
0)]+U
T
Because (D
6~D
0)=(2
7-1)-(D
6~D
0)
So U
O=LSB*[2
7(D
15~D
7+ 1)-(2
7-1)-(D
6~D
0)]+U
T
=LSB*[2
7(D
15~D
7)+(D
6~D
0)+1]+U
T
Because 2
7(D
15~D
7) be equivalent to (D
15~D
7) be moved to the left 7, with (D
6~D
0) addition just obtains:
U
O=LSB*(D
15~D
0+1)+U
T
The changing voltage formula:
So the scope of output voltage is [U
T+ LSB~U
T+ 2
16* LSB].
Calculate by deriving, we can obtain full scale (FS)=U of DAC
T+ 2
16* LSB, and realized 16 precision.Full scale, be divided into 2
16Part, and by changing input data, 2
16Individual scale can both reach.
Wherein, I
dRefer to total current, V
RefThe reference voltage that finger provides, U
cRefer to the voltage that c is ordered, U
BcRefer to that the b point is to the voltage between the c point, R
bRefer to c point resistance to earth, U
MCoarse tuning voltage after referring to quantize, U
NFine tuning voltage after referring to quantize, U
oRefer to the output voltage after the conversion, D refers to the binary data of the preparation conversion imported, and LSB refers to minimum quantization unit, U
TRefer to constant, D refers to the D negate.
Claims (3)
1, a kind of improved voltage marking D/A converter, it is characterized in that: in a string and combined resistance network, voltage is divided into roughly adjusted rheostat network and two parts of fine tuning resistor network, and be connected with the operational amplifier positive terminal at the output of roughly adjusted rheostat network, the output of fine tuning resistor network is connected with the negative phase end of operational amplifier, have the quantification diverter switch respectively on each resistance on roughly adjusted rheostat network and the fine tuning resistor network, correction resistance is connected in parallel on the fine tuning resistor network; During work, import binary data to be converted earlier, and these data are divided into a high position and low level, wherein low level goes to control the quantification diverter switch of fine tuning resistor network after decoding; Go to control the quantification diverter switch of roughly adjusted rheostat network after the high-order decoding, after quantizing, take out the positive terminal that a voltage is given operational amplifier from the roughly adjusted rheostat network, the fine tuning resistor network takes out the negative phase end that a voltage is given operational amplifier, through computing, draw the voltage after the conversion;
Utilize operational amplifier to carry out computing when computing, operational formula is: U
O=2U
M-U
N, U wherein
MCoarse tuning voltage after referring to quantize, U
NFine tuning voltage after referring to quantize, U
oOutput voltage after referring to change.
2, improved according to claim 1 voltage marking D/A converter is characterized in that: the output of fine tuning resistor network is connected with the negative phase end of operational amplifier after through a follower; The fine tuning resistor network takes out a voltage is given operational amplifier behind follower negative phase end.
3, improved according to claim 1 voltage marking D/A converter is characterized in that: wherein decoding again after the negate of low level elder generation.
Priority Applications (1)
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CNB2007101345023A CN100546195C (en) | 2007-10-31 | 2007-10-31 | A kind of improved voltage marking D/A converter |
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CNB2007101345023A CN100546195C (en) | 2007-10-31 | 2007-10-31 | A kind of improved voltage marking D/A converter |
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CN100546195C true CN100546195C (en) | 2009-09-30 |
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Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2011040904A (en) * | 2009-08-07 | 2011-02-24 | Renesas Electronics Corp | D/a converter |
CN102130688B (en) * | 2010-01-20 | 2015-06-03 | 上海华虹宏力半导体制造有限公司 | Resistance network type digital to analog converter structure |
EP2800276A4 (en) * | 2011-12-26 | 2016-04-13 | Qixing Chen | Multi-level parallel super-high speed adc and dac using logarithmic companding law |
CN109817169A (en) * | 2017-11-20 | 2019-05-28 | 上海视涯信息科技有限公司 | The driving circuit and image display device of display panel |
CN107809251B (en) * | 2017-11-22 | 2021-02-26 | 京东方科技集团股份有限公司 | Digital-to-analog conversion circuit and method thereof and display device |
JPWO2021131909A1 (en) * | 2019-12-27 | 2021-07-01 | ||
CN111565049B (en) * | 2020-07-20 | 2020-10-23 | 微龛(广州)半导体有限公司 | Binary weighted current generating circuit and digital-to-analog converter |
CN116195188A (en) * | 2021-09-26 | 2023-05-30 | 京东方科技集团股份有限公司 | Phase shifter, use method thereof and antenna system |
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Denomination of invention: An improved voltage marking D/A converter Effective date of registration: 20150728 Granted publication date: 20090930 Pledgee: Bank of Jiangsu, Limited by Share Ltd, Wuxi branch Pledgor: Wuxi Youxin Integrated Circuit Design Co.Ltd Registration number: 2015320010005 |
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