Algorithm analog-to-digital converter
View Patent ↗Provided is an algorithm analog-to-digital converter (ADC). The algorithm ADC obtains two digital outputs through different capacitor connections for one analog input signal and adds the digital output signals to obtain a final output value, so that a mismatch factor of the capacitor is removed to minimize a linearity limitation resulting from the capacitor mismatch. In addition, the algorithm ADC minimizes power consumption by making the operating frequency slow at a cycle requiring a high resolution and making the operating frequency fast at a cycle requiring a low resolution, i.e., outputting different operating clock frequencies according to a required resolution.
1. An algorithm analog-to-digital converter (ADC), comprising:
a sample-and-hold amplifier (SHA) for sampling and holding an input analog voltage;
two flash ADCs for converting one analog input signal into two digital signals n 1 and n 2 through different capacitor connections and outputting the two digital signals;
one multiplying digital-to-analog converter (MDAC) for amplifying a difference between an output voltage Vs of the SHA and a reference voltage ±Vref through different capacitor connections according to the digital signals output from the flash ADCs and outputting the amplified difference to the flash ADCs again;
a sequential multiphase clock generating circuit for outputting different operating clock frequencies according to the required resolution; and
an output stage for adding the two digital signals n 1 and n 2 output from the flash ADCs to obtain a final output value.
2. The algorithm ADC of claim 1 , wherein the sequential multiphase clock generating circuit outputs a clock signal whose clock cycle is gradually reduced during a clock phase of (n−1) times.
3. The algorithm ADC of claim 1 , wherein the sequential multiphase clock generating circuit outputs a clock signal of a low frequency at a cycle requiring a high resolution, and a clock signal of a high frequency at a cycle requiring a low resolution.
4. The algorithm ADC of claim 1 , wherein the flash ADCs output an n-bit digital signal n 1 at a (n−1)/2 cycle of a first section and an n-bit digital signal n 2 at a (n−1)/2 cycle of a second section.
5. The algorithm ADC of claim 4 , wherein the MADC operates at the (n−1)/2 cycle of the first section such that a second capacitor C 2 amplifies a difference between the output voltage Vs and the reference voltage ±Vref at a second phase Q 2 , and a fourth capacitor C 4 amplifies a difference between the output voltage Vs and the reference voltage ±Vref at a first phase Q 1 .
6. The algorithm ADC of claim 5 , wherein an output V MO1 (Q 2 ) of the MDAC at a second phase Q 2 of the first section is defined by:
V
MO
1
(
Q
2
)
=
(
2
C
1
+
α
C
1
+
α
)
·
(
V
S
-
k
2
2
)
(
D
1
D
2
=
11
->
k
2
=
+
V
REF
,
D
1
D
2
=
10
->
k
2
=
0
,
D
1
D
2
=
00
->
k
2
=
-
V
REF
)
,
where C 2 =C 1 +α.
7. The algorithm ADC of claim 5 , wherein an output V MO1 (Q 1 ) of the MDAC at a first phase Q 1 of the first section is defined by:
V
MO
1
(
Q
1
)
=
(
2
C
3
+
β
C
3
+
β
)
·
(
V
MO
1
(
Q
2
)
-
k
1
2
)
=
(
2
C
3
+
β
C
3
+
β
)
·
(
(
2
C
1
+
α
C
1
+
α
)
·
(
V
S
-
k
2
2
)
-
k
1
2
)
(
D
3
D
4
=
11
->
k
1
=
+
V
REF
,
D
3
D
4
=
10
->
k
1
=
0
,
D
3
D
4
=
00
->
k
1
=
-
V
REF
)
,
where C 4 =C 3 +α.
8. The algorithm ADC of claim 4 , wherein the MADC operates at the (n−1)/2 cycle of the second section such that a first capacitor C 1 amplifies a difference between the output voltage Vs and the reference voltage ±Vref at a second phase Q 2 , and a third capacitor C 3 amplifies a difference between the output voltage Vs and the reference voltage ±Vref at a first phase Q 1 .
9. The algorithm ADC of claim 8 , wherein an output V MO2 (Q 2 ) of the MDAC at the second phase Q 2 of the second section is defined by:
V
MO
2
(
Q
2
)
=
(
2
C
1
+
α
C
1
)
·
(
V
S
-
k
2
2
)
(
D
1
D
2
=
11
->
k
2
=
V
REF
,
D
1
D
2
=
10
->
k
2
=
0
,
D
1
D
2
=
00
->
k
2
=
V
REF
)
,
where C 2 =C 1 +α.
10. The algorithm ADC of claim 8 , wherein an output V MO2 (Q 1 ) of the MDAC at the first phase Q 1 of the second section is defined by:
V
MO
2
(
Q
1
)
=
(
2
C
3
+
β
C
3
)
·
(
V
MO
1
(
Q
2
)
-
k
1
2
)
=
(
2
C
3
+
β
C
3
)
·
(
(
2
C
1
+
α
C
1
)
·
(
V
S
-
k
2
2
)
-
k
1
2
)
(
D
3
D
4
=
11
->
k
1
=
V
REF
,
D
3
D
4
=
10
->
k
1
=
0
,
D
3
D
4
=
00
->
k
1
=
-
V
REF
)
,
where C 4 =C 3 +α.
11. The algorithm ADC of claim 1 , wherein the output stage comprises:
a plurality of latches for storing the digital signals output from the flash ADCs;
a digital correction circuit for correcting an error of the digital signals output from the flash ADCs; and
an adder for adding the two digital signals output from the flash ADCs to output the final output value.
12. The algorithm ADC of claim 7 , wherein the final output value V MO (Q 1 ) at the first phase Q 1 is defined by:
V
MO
(
Q
1
)
=
V
MO
1
(
Q
1
)
+
V
MO
2
(
Q
1
)
=
(
2
C
3
+
β
C
3
+
β
)
·
(
V
MO
1
(
Q
2
)
-
k
1
2
)
+
(
2
C
3
+
β
C
3
)
·
(
V
MO
2
(
Q
2
)
-
k
1
2
)
=
k
1
2
(
2
C
3
+
β
C
3
+
2
C
3
+
β
C
3
+
β
)
+
(
V
S
-
k
2
2
)
[
(
2
C
3
+
β
C
3
+
β
)
·
(
2
C
1
+
α
C
1
+
α
)
+
(
2
C
3
+
β
C
3
)
·
(
2
C
1
+
α
C
1
)
]
≅
k
1
2
(
4
C
3
+
4
C
3
β
C
3
+
β
)
+
(
V
S
-
k
2
2
)
[
8
C
1
2
C
2
2
+
8
C
1
C
2
2
α
+
8
C
1
2
C
2
β
C
1
2
C
2
2
+
C
1
C
2
2
α
+
C
1
2
C
2
β
]
=
2
k
1
+
8
(
V
S
-
k
2
2
)
,
(
C
1
,
C
2
⪡
α
,
β
)
.
13. The algorithm ADC of claim 6 , wherein the final output value V MO (Q 2 ) at the second phase Q 2 is defined by:
V
MO
(
Q
2
)
=
V
MO
1
(
Q
2
)
+
V
MO
2
(
Q
2
)
=
(
2
C
1
+
α
C
1
+
2
C
1
+
α
C
1
+
α
)
·
(
V
S
-
k
2
2
)
≅
(
2
C
1
2
+
2
C
1
α
C
1
2
+
C
1
α
)
·
(
V
S
-
k
2
2
)
=
2
(
V
S
-
k
2
2
)
,
(
C
1
⪡
α
)
.