AD9963 Analog Devices, AD9963 Datasheet - Page 52

• Manufacturer Part Number: AD9963
• Description: 10-/12-Bit, Low Power, Broadband MxFE
• Manufacturer: Analog Devices

Specifications of AD9963

• Resolution (bits): 12bit
• Throughput Rate: 100MSPS
• # Chan: 2
• Supply V: Multi(+1.8Anlg, +1.8Dig),Multi(+1.8Anlg, +3.3Dig) ,Single(+1.8),Single(+3.3)
• Sample Rate: 100MSPS
• Adc Bits X #adcs-speed: 12x2-100 MHz
• Dac Bits X #dacs-clkspeed: 12x2-170 MHz
• Pkg Type: CSP
• Primary Application: Broadband Wireless

AD9961/AD9963
AUXILIARY CONVERTERS
The AD9961/AD9963 have two fast settling servo DACs, along
with an analog input and two analog I/O pins. All of the
auxiliary converters run off a dedicated supply pin. The input
and output compliance ranges depend on the voltage supplied.
AUXILIARY ADC
The auxiliary ADC is a 12-bit SAR converter that is accessed
and controlled through the serial port registers (Register 0x77
through Register 0x7B). The ADC voltage reference and clock
signals are generated on chip. The auxiliary ADC is preceded by
a seven-input multiplexer. The ADC inputs can be connected to
either the AUXIN1, AUXIO2, AUXIO3 input pins, or one of
four internal signals as shown in Figure 85.
CONVERSION CLOCK
The auxiliary ADC conversion clock is generated through a
programmable binary division of the CLK input signal. The
frequency of the ADC conversion clock is programmable and
can be calculated from the following equation:
where R is programmed through Register 0x7A, Bits[2:0].
For best performance and lowest power consumption, the
conversion clock speed should be set to the lowest speed that
meets the system conversion time requirements. The maximum
allowable auxiliary ADC clock speed is 10 MHz.
Voltage Reference
The auxiliary ADC has an internal, temperature stable, 2.5 V
reference. This results in an input voltage range of 0 V to 3.2 V.
When using the internal voltage reference, the AUXADCREF
pin should be decoupled to AGND through a 0.22 µF capacitor.
The AUXADCREF pin can be used as a reference output to
external devices, but the current load on the pin should be
limited to sourcing less than 5 mA and sinking less than 100 µA.
For systems with tight accuracy requirements, a higher accuracy
external reference can be used to source a voltage into the
AUXREF
f
AUXCLK
CLK
Figure 85. Block Diagram of Auxiliary ADC Circuitry
=
REG 0x7A[2:0]
f
CLK
R
/R
2.5V
AUXADCCLK
DAC10A
DAC10B
AUX
DAC
AUX
AUX
REG 0x77[2:0]
SEL
110
100
101
011
111
000
001
010
VRxCML
VCMLI
VCMLQ
VPTAT
VINT
AUXIO3
AUXIN1
AUXIO2
Rev. 0 | Page 52 of 60
AUXADCREF pin. The input voltage range for external voltage
references is from 1.0 V to 2.5 V. The input impedance of the
AUXADCREF pin is 100 kΩ. The full-scale input voltage of the
ADC is a function of the voltage reference as:
Analog Inputs
The ADC can be configured to sample one of eight analog
inputs. The input is selected through the channels select bits
(Register 0x77, Bits[2:0]). These eight signals are described in
Table 28.
Table 28. Auxiliary ADC Channel Selections
Channel
Select
000
001
010
011
100
101
110
111
When selected, Input Pin 70, Pin 71, and Pin 72 are connected
to the sampling cap of the auxiliary ADC. Therefore, the
circuits driving these inputs need to recover to the desired
accuracy from having a discharged 10 pF capacitor connected
to it at the initiation of the conversion, within the sampling
window. A programmable delay (Register 0x7B, Bits[1:0]) can
be added to the conversion cycle time to allow additional
settling time of the input. If the ADC input is driven from a low
source impedance, like the output of an op amp, a 20-cycle
conversion time should yield good results. Higher impedance
sources may require the 34-cycle conversion time to fully settle.
Where the conversion cycle time is not an issue, it is
recommended that the full 34-cycle conversion time be used.
Conversions where the input multiplexer is switched between
inputs require a longer conversion cycle time than consecutive
conversions from the same multiplexer input.
V
AUXFS
Signal
AUXIN1
AUXIO2
AUXIO3
VPTAT
VCMLI
VCMLQ
RXCML
GND
=
3
2
2 .
5 .
×
V
AUXREF
Description
Pin 72.
Pin 71. The auxiliary DAC10A should be
disabled when using this pin as an input.
Pin 70. The auxiliary DAC10B should be
disabled when using this pin as an input.
Voltage proportional to absolute
temperature scaled to 0.2 °K per LSB.
Therefore, the temperature in degrees C
is:
Common mode level of the I and Q Rx
ADC buffers. Should measure
approximately 0.9 V. The buffer must be
enabled (see Configuration Register
0x7E).
The RXCML output voltage on Pin 10. This
should measure approximately 1.4 V.
Should measure 0 V.
T
(C
o
)
=
ADC
_
5
CODE
−
273
2 .