AD10465/PCB Analog Devices Inc, AD10465/PCB Datasheet - Page 12

• Manufacturer Part Number: AD10465/PCB
• Description: KIT EVAL PCB FOR AD10465
• Manufacturer: Analog Devices Inc

Specifications of AD10465/PCB

• Rohs Status: RoHS non-compliant
• Number Of Adc's: 2
• Number Of Bits: 14
• Sampling Rate (per Second): 65M
• Data Interface: Parallel
• Inputs Per Adc: 1 Single Ended
• Input Range: ±2 V
• Power (typ) @ Conditions: 3.5W @ 65MSPS
• Voltage Supply Source: Analog and Digital, Dual ±
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD10465
• Lead Free Status / RoHS Status: Not Compliant

AD10465
THEORY OF OPERATION
The AD10465 is a high dynamic range, 14-bit, 65 MHz pipeline
delay (three pipelines) analog-to-digital converter. The custom
analog input section maintains the same input ranges (1 V p-p,
2 V p-p, and 4 V p-p) and input impedance (100 Ω, 200 Ω, and
400 Ω) as the AD10242.
The AD10465 employs four monolithic Analog Devices
components per channel (AD8037, AD8138, AD8031, and
AD6644), along with multiple passive resistor networks and
decoupling capacitors to fully integrate a complete 14-bit
analog-to-digital converter.
The input signal is passed through a precision laser trimmed
resistor divider allowing the user to externally select operation
with a full-scale signal of ±0.5 V, ±1.0 V, or ±2.0 V by choosing
the proper input terminal for the application.
The AD10465 analog input includes an AD8037 amplifier
featuring an innovative architecture that maximizes the
dynamic range capability on the amplifiers inputs and outputs.
The AD8037 amplifier provides a high input impedance and
gain for driving the AD8138 in a single-ended to differential
amplifier configuration. The AD8138 has a −3 dB bandwidth at
300 MHz and delivers a differential signal with the lowest
harmonic distortion available in a differential amplifier. The
AD8138 differential outputs help balance the differential inputs
to the AD6644, maximizing the performance of the ADC.
The AD8031 provides the buffer for the internal reference of the
AD6644. The internal reference voltage of the AD6644 is
designed to track the offsets and drifts of the ADC and is used
to ensure matching over an extended temperature range of
operation. The reference voltage is connected to the output
common-mode input on the AD8138. The AD6644 reference
voltage sets the output common mode on the AD8138 at 2.4 V,
which is the midsupply level for the AD6644.
Table 5. Input Impedance Options
Input
A
A
A
IN
IN
IN
1
2
3
Impedance
100 Ω
75 Ω
50 Ω
200 Ω
100 Ω
75 Ω
50 Ω
400 Ω
100 Ω
75 Ω
50 Ω
Condition
When A
When A
When A
When A
When A
When A
When A
When A
When A
When A
Rev. A | Page 12 of 24
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
2 and A
3 is shorted to GND
2 is shorted to GND
3 is open
3 is shorted to GND
2 to A
2 to A
3 has an external resistor of 133 Ω to GND
3 has an external resistor of 92 Ω to GND
3 has an external resistor of 57 Ω to GND
The AD6644 has complementary analog input pins, AIN and
AIN . Each analog input is centered at 2.4 V and should swing
±0.55 V around this reference. Since AIN and AIN are 180° out
of phase, the differential analog input signal is 2.2 V peak-to-
peak. Both analog inputs are buffered prior to the first track-
and-hold, TH1. The high state of the ENCODE pulse places
TH1 in hold mode. The held value of TH1 is applied to the
input of a 5-bit coarse ADC1. The digital output of ADC1
drives 14 bits of precision, which is achieved through laser
trimming. The output of DAC1 is subtracted from the delayed
analog signal at the input of TH3 to generate a first residue
signal. TH2 provides an analog pipeline delay to compensate for
the digital delay of ADC1.
The first residue signal is applied to a second conversion stage
consisting of a 5-bit ADC2, 5-bit DAC2, and pipeline TH4. The
second DAC requires 10 bits of precision, which is met by the
process with no trim. The input to TH5 is a second residue
signal generated by subtracting the quantized output of DAC2
from the first residue signal held by TH4. TH5 drives a final
6-bit ADC3.
The digital outputs from ADC1, ADC2, and ADC3 are added
together and corrected in the digital error correction logic to
generate the final output data. The result is a 14-bit parallel
digital CMOS-compatible word, coded as twos complement.
USING THE FLEXIBLE INPUT
The AD10465 has been designed with the user’s ease of opera-
tion in mind. Multiple input configurations have been included
on board to allow the user a choice of input signal levels and
input impedance. While the standard inputs are ±0.5 V, ±1.0 V,
and ±2.0 V, the user can select the input impedance of the
AD10465 on any input by using the other inputs as alternate
locations for GND or an external resistor. Table 5 summarizes
the impedance options available at each input location.
IN
IN
3 has an external resistor of 300 Ω, with A
3 has an external resistor of 100 Ω, with A
IN
3 are open
IN
IN
3 shorted to GND
3 shorted to GND