Quiz: SAR ADC Input Types
TIPL 4003
TI Precision Labs – SAR
Created by Art Kay
1
Quiz: SAR ADC Input Types
1. The circuit in the figure below is a ____.
Single ended ADC.
Pseudo-differential ADC.
Fully Differential ADC.
True Differential ADC.
IOP1
-
22Ω
3V
2V
AVDD
Vref
DVDD
AIN_P
+
C1 1nF
+
a.
b.
c.
d.
0V to
3V
ADS7043
+1.5V
AIN_M
AGND
DGND
2
Quiz: SAR ADC Input Types
2. (T/F) The signal below can be directly applied to an ADC with a fully
differential input.
a. True.
b. False.
ADC Input Viltage
Common Mode Voltage
ADC Input Voltage
5
AIN_M
4
3
2
1
AIN_P
0
0
0.5
1
1.5
Time
2
2.5
3
Common Mode Voltage (V)
ADC Input
5
4
Vcm =
3
AIN_P + AIN_M
2
2
1
0
0
0.5
1
1.5
2
2.5
3
Time
3
Quiz: SAR ADC Input Types
3. (T/F) The signal below can be directly applied to an ADC with a fully
differential input.
a. True.
b. False.
ADC Input Voltage
ADC Input Voltages
Common Mode Voltage
Common Mode Voltage (V)
ADC Input Voltage (V)
5
AIN_M
4
3
2
1
AIN_P
0
5
Vcm =
4
AIN_P + AIN_M
2
3
2
1
0
0
0.5
1
1.5
Time
2
2.5
3
0
0.5
1
1.5
Time
2
2.5
3
4
Quiz: SAR ADC Input Types
4. Which type of ADC would require a wide bandwidth amplifier and a RC charge
bucket filter?
a. A high voltage SAR with an internal PGA.
b. A switched capacitor input SAR ADC.
5. (T/F) In general, a fully differential input has double the range of a single
ended input assuming the same reference voltage.
a. True.
b. False.
5
Quiz: SAR ADC Input Types
6. The circuit in the figure below has a ____.
a. Unipolar, differential input.
b. Bipolar, differential input.
5V
3V
3V
Vref
AVDD
DVDD
AIN_P
AIN_M
3V
3V
Vref
AVDD
DVDD
AIN_P
AIN_P
AIN_P
Vin
0V Vin_dif
-5V
5V
ADS8881
Vin
5V Vin_dif
+5V
AIN_M
AIN_M
AGND
DGND
Negative Full Scale Input
AIN_M
AGND
Vin
0V
DGND
1.0
Vin
5V
ADS8881
Positive Full Scale Input
6
Solutions
7
Solutions Quiz: SAR ADC Input Types
1. The circuit in the figure below is a ____.
Single ended ADC.
Pseudo-differential ADC.
Fully Differential ADC.
True Differential ADC.
IOP1
-
22Ω
3V
2V
AVDD
Vref
DVDD
AIN_P
+
C1 1nF
+
a.
b.
c.
d.
0V to
3V
ADS7043
+1.5V
AIN_M
AGND
DGND
8
Solutions Quiz: SAR ADC Input Types
2. (T/F) The signal below can be directly applied to an ADC with a fully
differential input.
a. True.
b. False.
ADC Input Viltage
Common Mode Voltage
ADC Input Voltage
5
AIN_M
4
3
2
1
AIN_P
0
0
0.5
1
1.5
Time
2
2.5
3
Common Mode Voltage (V)
ADC Input
5
4
Vcm =
3
AIN_P + AIN_M
2
2
1
0
0
0.5
1
1.5
2
2.5
3
Time
9
Solutions Quiz: SAR ADC Input Types
3. (T/F) The signal below can be directly applied to an ADC with a fully
differential input.
a. True.
b. False.
ADC Input Voltage
ADC Input Voltages
Common Mode Voltage
Common Mode Voltage (V)
ADC Input Voltage (V)
5
AIN_M
4
3
2
1
AIN_P
0
5
Vcm =
4
AIN_P + AIN_M
2
3
2
1
0
0
0.5
1
1.5
Time
2
2.5
3
0
0.5
1
1.5
Time
2
2.5
3
10
Solutions Quiz: SAR ADC Input Types
4. Which type of ADC would require a wide bandwidth amplifier and a RC charge
bucket filter?
a. A high voltage SAR with an internal PGA.
b. A switched capacitor input SAR ADC.
5. (T/F) In general, a fully differential input has double the range of a single
ended input assuming the same reference voltage.
a. True.
b. False.
11
Solutions Quiz: SAR ADC Input Types
6. The circuit in the figure below has a ____.
a. Unipolar, differential input.
b. Bipolar, differential input.
5V
3V
3V
Vref
AVDD
DVDD
AIN_P
AIN_M
3V
3V
Vref
AVDD
DVDD
AIN_P
AIN_P
AIN_P
Vin
0V Vin_dif
-5V
5V
ADS8881
Vin
5V Vin_dif
+5V
AIN_M
AIN_M
AGND
DGND
Negative Full Scale Input
AIN_M
AGND
Vin
0V
DGND
1.0
Vin
5V
ADS8881
Positive Full Scale Input
12