HITTITE HMCAD1102

HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Features
Typical Applications
• 80 MSPS Maximum Sampling Rate
• Medical Imaging
• Ultra Low Power Dissipation
59 mW/Channel at 80MSPS
• Wireless Infrastructure
• Test and Measurement
• 70.1 dB SNR at 8 MHz FIN
• Instrumentation
• 0.5 µs Startup from Sleep
15 µs from Power Down
• Reduced Power Dissipation Modes Available
• Internal Reference Circuitry
with No External Components Required
0
Pin Compatible Parts
• HMCAD1101
• HMCAD1100
• Coarse and Fine Gain Control
• HMCAD1100/01-AC specifications are
also valid for HMCAD1102
• Internal Offset Correction
• 1.8V Supply Voltage
A / D Converters - SMT
• Serial 12-Bit LVDS Output
• 14-bit LVDS Output Available Up to 65MSPS
• 64 Lead 9 x 9 mm SMT Package
Functional Diagram
Figure 1. Functional Block Diagram
0-1
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
General Description
HMCAD1102 is a high performance low power octal analog-to-digital converter (ADC). The ADC is based on a
proprietary structure and employs internal reference circuitry, a serial control interface and serial LVDS output data.
Data and frame synchronization output clocks are supplied for data capture at the receiver.
Various modes and configuration settings can be applied to the ADC through the serial control interface (SPI). Each
channel can be powered down independently and data format can be selected through this interface. A full chip idle
mode can be set by a single external pin. Register settings determine the exact function of this external pin.
The HMCAD1102 is designed to easily interface with field-programmable gate arrays (FPGAs) from several vendors.
The very low start up times for the HMCAD1102 allows significant power reduction in duty-cycled systems, by utilizing
the Sleep Modes or Power Down Mode when the receive path is idle.
0
Electrical Specifications
AVDD = 1.8V, DVDD = 1.8V, OVDD = 1.8V, 80 MSPS clock, 50% clock duty cycle, -1 dBFS 8 MHz input signal, 12 bit output, unless otherwise noted
Parameter
Description
Min
Typ
Max
Unit
DC accuracy
No Missing Codes
Offset Error
Guaranteed
Offset error after internal digital offset correction
1
Gain Error
LSB
±6
%FS
Gain matching between channels. ±3sigma
value at worst case conditions
±0.5
%FS
DNL
Differential nonlinearity (12-bit level)
±0.2
LSB
INL
Integral nonlinearity (12-bit level)
±0.6
LSB
VCM
Common mode voltage output
VAVDD/2
Gain Matching
Analog Input
Input Common Mode
Analog input common mode voltage
Full Scale Range
Differential input voltage range
Input Capacitance
Differential input capacitance
Bandwidth
Input Bandwidth
VCM -0.1
VCM +0.2
2
V
Vpp
2
pF
500
A / D Converters - SMT
DC Electrical Specifications
MHz
Power Supply
Analog Supply Voltage
1.7
1.8
2
V
Digital Supply Voltage
Digital and output driver supply voltage (up to
65 MSPS)
1.7
1.8
2
V
Digital Supply Voltage
Digital and output driver supply voltage (above
65 MSPS)
1.8
1.9
2
V
OVDD Supply Voltage
Digital CMOS Input Supply Voltage
1.7
1.8
3.6
V
Operating free-air temperature
-40
85
°C
Temperature
Operating Temperature
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0-2
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
AC Electrical Specifications - 80 MSPS
AVDD = 1.8V, DVDD = 1.8V, OVDD = 1.8V, 80 MSPS clock, 50% clock duty cycle, -1 dBFS 8 MHz input signal, 12 bit output, unless otherwise noted
Parameter
Description
Min
Typ
Max
Unit
68.5
70.1
dBFS
70
dBFS
69.6
dBFS
69.5
dBFS
77
dBc
76
dBc
90
dBc
90
dBc
77
dBc
76
dBc
FIN = 8 MHz
11.3
bits
FIN = 30 MHz
11.3
bits
Signal applied to 7 channels (FIN0). Measurement taken on one channel with full scale at FIN1.
FIN1=8MHz, FIN0=9.9MHz
95
dBc
173
mA
88
mA
Analog Power
312
mW
Digital Power
158
mW
Total Power Dissipation
470
mW
Performance
SNR
Signal to Noise Ratio
FIN = 8 MHz
FIN = 30 MHz
SINAD
Signal to Noise and Distortion Ratio
FIN = 8 MHz
68
FIN = 30 MHz
SFDR
0
FIN = 8 MHz
74
FIN = 30 MHz
HD2
A / D Converters - SMT
Spurious Free Dynamic Range
Second order Harmonic Distortion
FIN = 8 MHz
85
FIN = 30 MHz
HD3
Third order Harmonic Distortion
FIN = 8 MHz
75
FIN = 30 MHz
ENOB
Crosstalk
Effective number of Bits
Power Supply
Analog Supply Current
Digital Supply Current
Digital and output driver supply
Power Down
Power down mode dissipation
10
µW
Sleep Mode
Deep sleep mode power dissipation
56
mW
Power dissipation with all channels in sleep channel
mode (Light sleep)
116
mW
Power dissipation savings per channel off
44
mW
Sleep Channel Mode
Sleep Channel Savings
Clock Inputs
Max. Conversion Rate
Min. Conversion Rate
0-3
80
MSPS
20
MSPS
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Digital and Switching Specifications
AVDD = 1.8V, DVDD = 1.8V, OVDD = 1.8V, unless otherwise noted
Parameter
Description
Min
Typ
Max
Unit
80
% high
Clock Inputs
Duty Cycle
20
Compliance
CMOS, LVDS, LVPECL
Input range, diff
Differential input swing
±200
mVpp
Input range, sine
Differential input swing, sine wave clock input
±800
mVpp
Input range, CMOS
Voltage input range CMOS (CLKN connected
to ground)
Keep voltages within ground and voltage of
OVDD
Input capacitance
0.3
Differential
VOVDD -0.3
2
V
pF
Logic inputs (CMOS)
VHI
High Level Input Voltage. VOVDD ≥ 3.0V
2
V
VHI
High Level Input Voltage. VOVDD = 1.7V – 3.0V
0.8 ·VOVDD
V
VLI
Low Level Input Voltage. VOVDD ≥ 3.0V
0
0.8
VLI
Low Level Input Voltage. VOVDD = 1.7V – 3.0V
0
0.2·VOVDD
V
IHI
High Level Input leakage Current
±10
µA
ILI
Low Level Input leakage Current
±10
µA
CI
Input Capacitance
3
V
pF
Data outputs (LVDS)
Compliance
LVDS
VOUT
Differential output voltage
VCM
Output coding
350
mV
Output common mode voltage
1.2
V
Default/optional
Offset Binary/ 2’s complement
Timing Characteristics
Aperture delay
Aperture jitter
TSU
TSLPCH
Start up time from Power Down Mode
and Deep Sleep Mode to Active Mode.
References have reached 99% of final value.
See section “Clock Frequency”
0.8
ns
<0.5
ps
260
992
clock cycles
Start up time from Power Down Mode and
Deep Sleep Mode to Active Mode in µs.
15
µs
Start up time from Sleep Channel Mode to
Active Mode
0.5
µs
TOVR
Out of range recovery time
1
clock cycles
TLAT
Pipeline delay
14
clock cycles
LCLK to data delay time (excluding
programmable phase shift)
250
ps
0
A / D Converters - SMT
Input common mode voltage
VOVDD
LVDS Output Timing Characteristics
tdata
TPROP
Clock propagation delay.
7*TLVDS + 2.6
LVDS bit-clock duty-cycle
45
7*TLVDS + 3.5
Frame clock cycle-to-cycle jitter
7*TLVDS + 4.2
ns
55
%LCLK cycle
2.5
%LCLK cycle
TEDGE
Data rise- and fall time 20% to 80%
0.4
ns
TCLKEDGE
Clock rise- and fall time 20% to 80%
0.4
ns
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0-4
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Absolute Maximum Ratings
Applying voltages to the pins beyond those specified
in Table 1 could cause permanent damage to the
circuit.
Table 1: Absolute Maximum Ratings
Pin
A / D Converters - SMT
0
0-5
Reference pin
Rating
AVDD
AVSS
-0.3V to +2.3V
DVDD
DVSS
-0.3V to +2.3V
OVDD
AVSS
-0.3V to +3.9V
AVSS / DVSS
DVSS / AVSS
-0.3V to +0.3V
Analog inputs and
outputs
AVSS
-0.3V to +2.3V
CLKx
AVSS
-0.3V to +3.9V
LVDS outputs
DVSS
-0.3V to +2.3V
Digital inputs
DVSS
-0.3V to +3.9V
ELECTROSTATIC SENSITIVE DEVICE
OBSERVE HANDLING PRECAUTIONS
Stresses above those listed under Absolute Maximum
Ratings may cause permanent damage to the device. This
is a stress rating only; functional operation of the device
at these or any other conditions above those indicated in
the operational section of this specification is not implied.
Exposure to absolute maximum rating conditions for
extended periods may affect device reliability.
Table 2: Maximum Temperature Ratings
Operating Temperature
-40 to +85 °C
Storage Temperature
-60 to +150 °C
Maximum Junction Temperature
Thermal Resistance (Rth)
Soldering Profile Qualification
110 °C
25 °C/W
J-STD-020
ESD Sensivity HBM
Class 1C
ESD Sensivity CDM
Class III
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Pin Configuration and Description
Figure 2. Package diagram
Table 3: Pin Descriptions
Pin Number
Function
Description
49, 50, 57
AVDD
Analog power supply, 1.8V
60
OVDD
Digital CMOS Inputs supply voltage
3, 6, 9, 37, 40, 43, 46
AVSS
Analog ground
1
IP1
Positive differential input signal, channel 1
2
IN1
Negative differential input signal, channel 1
4
IP2
Positive differential input signal, channel 2
5
IN2
Negative differential input signal, channel 2
7
IP3
Positive differential input signal, channel 3
8
IN3
Negative differential input signal, channel 3
10
IP4
Positive differential input signal, channel 4
11
IN4
Negative differential input signal, channel 4
38
IP5
Positive differential input signal, channel 5
39
IN5
Negative differential input signal, channel 5
41
IP6
Positive differential input signal, channel 6
42
IN6
Negative differential input signal, channel 6
44
IP7
Positive differential input signal, channel 7
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
A / D Converters - SMT
0
0-6
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Table 3: Pin Descriptions
A / D Converters - SMT
0
0-7
Pin Number
Function
Description
45
IN7
Negative differential input signal, channel 7
47
IP8
Positive differential input signal, channel 8
48
IN8
Negative differential input signal, channel 8
0, 12, 14, 36
DVSS
Digital ground
35
DVDD
Digital and I/O power supply, 1.8V
13
PD
Power-down input. Activate after applying power in order to initialize the ADC
correctly. Alternatively use the SPI power down feature
15
D1P
LVDS channel 1, positive output
16
D1N
LVDS channel 1, negative output
17
D2P
LVDS channel 2, positive output
18
D2N
LVDS channel 2, negative output
19
D3P
LVDS channel 3, positive output
20
D3N
LVDS channel 3, negative output
21
D4P
LVDS channel 4, positive output
22
D4N
LVDS channel 4, negative output
27
D5P
LVDS channel 5, positive output
LVDS channel 5, negative output
28
D5N
29
D6P
LVDS channel 6, positive output
30
D6N
LVDS channel 6, negative output
31
D7P
LVDS channel 7, positive output
32
D7N
LVDS channel 7, negative output
33
D8P
LVDS channel 8, positive output
34
D8N
LVDS channel 8, negative output
23
FCLKP
LVDS frame clock (1X), positive output
24
FCLKN
LVDS frame clock (1X), negative output
25
LCKP
LVDS bit clock, positive output
26
LCKN
LVDS bit clock, negative output
51
NC
Not connected
52
TP
Test pin, leave unconnected or connect to ground
53
VCM
Common mode output pin, 0.5*AVDD
54
NC
Not connected
55
NC
Not connected
56
NC
Not connected
58
CLKP
Positive differential input clock
59
CLKN
Negative differential input clock.
Chip select enable. Active low
61
CSN
62
SDATA
Serial data input
63
SCLK
Serial clock input
64
RESETN
Reset SPI interface. Active low
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Serial Interface
The HMCAD1102 configuration registers can be accessed through a serial interface formed by the pins SDATA (serial
interface data), SCLK (serial interface clock) and CSN (chip select, active low). The following occurs when CSN is set
low:
•
•
•
Serial data are shifted into the chip
At every rising edge of SCLK, the value present at SDATA is latched
SDATA is loaded into the register every 24th rising edge of SCLK
Multiples of 24-bit words data can be loaded within a single active CSN pulse. If more than 24 bits are loaded into
SDATA during one active CSN pulse, only the first 24 bits are kept. The excess bits are ignored. Every 24-bit word is
divided into two parts:
•
•
The first eight bits form the register address
The remaining 16 bits form the register data
Acceptable SCLK frequencies are from 20 MHz down to a few hertz. Duty-cycle does not have to be tightly controlled.
0
Figure 4 shows the timing of the serial port interface. Table 5 explains the timing variables used in figure 4.
thi
tlo
tcs
CSN
tck
ts
tchi
tch
th
SCLK
SDATA
A7
A6
A5
A4
A3
A2
A1
A0
D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3 D2
D1
D0
Figure 3. Serial Port Interface timing
Table 5: Serial Port Interface timing definitions
Parameter
Description
Minimum Value
Unit
tcs
Setup time between CSN and SCLK
8
ns
tch
Hold time between CSN and SCLK
8
ns
ns
thi
SCLK high time
20
tlo
SCLK low time
20
ns
tck
SCLK period
50
ns
ts
Data setup time
5
ns
th
Data hold time
5
ns
A / D Converters - SMT
Timing Diagram
Start up Initialization
As part of the HMCAD1102 power-on sequence both a reset and a power down cycle have to be applied to ensure
correct start-up initialization. Make sure that the supply voltages are properly settled before the start up initialization
is being performed. Reset can be done in one of two ways:
1. By applying a low-going pulse (minimum 20 ns) on the RESETN pin (asynchronous).
2. By using the serial interface to set the ‘rst’ bit high. Internal registers are reset to default values when this
bit is set. The ‘rst’ bit is self-reset to zero. When using this method, do not apply any low-going pulse on the
RESETN pin.
Power down cycling can be done in one of two ways:
1. By applying a high-going pulse (minimum 20 ns) on the PD pin (asynchronous).
2. By cycling the SPI register 0Fhex ‘pd’ bit to high (reg value ‘0200’hex) and then low (reg value ‘0000’hex).
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0-8
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Timing Diagrams
N+14
Analog input
N+15
ADC clock
0
TLVDS
LCLKP
LCLKN
FCLKN
FCLKP
Dxx<1:0>
D10 D11 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D0
N-2 N-2 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N
D1
N
D2
N
D3
N
D4
N
D5
N
D6
N
D7
N
D8
N
D9
N
D10
N
A / D Converters - SMT
TPROP
0-9
Figure 4. LVDS timing 12 bit output, DDR mode
N+14
Analog input
N+15
ADC clock
TLVDS
LCLKN
LCLKP
FCLKN
FCLKP
Dxx<1:0>
D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D0
N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N
D1
N
D2
N
D3
N
D4
N
D5
N
D6
N
D7
N
D8
N
D9
N
D10 D11 D12 D13
N
N
N
N
TPROP
Figure 5. LVDS timing 14 bit output, DDR mode
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
N+14
Analog input
N+15
ADC clock
TLVDS
LCLKN
LCLKP
FCLKN
FCLKP
Dxx<1:0>
D10 D11 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D0
N-2 N-2 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N
D1
N
D2
N
D3
N
D4
N
D5
N
D6
N
D7
N
D8
N
D9
N
D10
N
0
TPROP
TLVDS
LCLKP
LCLKN
Dxx<1:0>
TLVDS /2
tdata
Figure 7. LVDS data timing, DDR mode
Serial Register Map
Table 6: Summary of functions supported by the serial interface
Name
rst
pd_ch
<8:1>
sleep
pd
pd_pin_cfg
<1:0>
ilvds_lclk
<2:0>
ilvds_
frame<2:0>
ilvds_dat
<2:0>
Description
Default
Self-clearing software
Inactive
reset
Channel-specific powerInactive
down
Go to sleep-mode
Inactive
Go to power-down
Inactive
Configures the PD pin for PD pin configured for
sleep-modes
power-down mode
LVDS current drive
programmability for
3.5 mA drive
LCLKP and LCLKN pins
LVDS current drive
programmability for
3.5 mA drive
FCLKP and FCLKN pins
LVDS current drive
programmability for output
3.5 mA drive
data pins
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
X
X
X
X
X
00
X
X
0F
X
X
Address
In Hex
A / D Converters - SMT
Figure 6. LVDS timing 12 bit output, SDR mode
X
X
X
X
X
X
X
X
X
11
X
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0 - 10
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Table 6: Summary of functions supported by the serial interface
Name
Description
Enables internal
termination for LVDS
buffers
Programmable termination
term_lclk
for LCLKN and LCLKP
<2:0>
buffers
Programmable termination
term_frame
for FCLKN and FCLKP
<2:0>
buffers
term_dat
Programmable termination
<2:0>
for output data buffers
invert_ch
Swaps the polarity of the
<8:1>
analog input pins
Enables a repeating fullen_ramp
scale ramp pattern on the
outputs
Enables the mode
dual_custom_ wherein the output toggles
pat
between two defined
codes
Enables the mode wherein
single_custom_
the output is a constant
pat
specified code
Bits for the single custom
bits_custom1
pattern and for the first
<13:0>
code of the dual custom
pattern. <0> is the LSB
en_lvds_term
A / D Converters - SMT
0
bits_custom2 Bits for the second code of
<13:0>
the dual custom pattern
gain_ch1
<3:0>
Programmable gain for
channel 1
gain_ch2
<3:0>
gain_ch3
<3:0>
gain_ch4
<3:0>
gain_ch5
<3:0>
gain_ch6
<3:0>
gain_ch7
<3:0>
gain_ch8
<3:0>
Programmable gain for
channel 2
Programmable gain for
channel 3
Programmable gain for
channel 4
Programmable gain for
channel 5
Programmable gain for
channel 6
Programmable gain for
channel 7
Programmable gain for
channel 8
Controls the phase of
LCLK output relative to
data
Enables deskew pattern
mode
Enables sync pattern
mode
phase_ddr
<1:0>
pat_deskew
pat_sync
0 - 11
Default
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Termination disabled
X
Termination disabled
1
X
X
Address
In Hex
X
12
Termination disabled
1
X
X
X
Termination disabled
1
X
X
X
Inactive
X
0
0
Inactive
0
X
0
Inactive
0
0
X
X
X
X
IPx is positive input
X
X
X
X
X
24
25
Inactive
X
X
X
X
X
X
X
X
X
X
X
X
X
X
26
Inactive
X
X
X
X
X
X
X
X
X
X
X
X
X
X
27
X
X
0dB gain
0dB gain
X
X
X
X
X
X
2A
0dB gain
0dB gain
X
X
X
X
0dB gain
X
X
X
X
0dB gain
X
X
X
X
X
X
X
X
2B
0dB gain
X
X
X
0dB gain
90 degrees
X
X
X
X
X
X
X
42
Inactive
0
X
Inactive
X
0
45
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Table 6: Summary of functions supported by the serial interface
btc_mode
msb_first
en_sdr
fall_sdr
perfm_cntrl
<2:0>
ext_vcm_bc
<1:0>
Description
Default
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Binary two’s complement
format for ADC output
Straight offset binary
data
Serialized ADC output
data comes out with MSB
LSB-first output
first
Enable SDR output mode.
LCLK becomes a 12X/14X DDR output mode
input clock
Rising edge of LCLK
comes in the middle of the
Rising edge
data window in SDR mode
ADC performance control
VCM buffer driving
strength control
Controls LVDS power
lvds_pd_mode
down mode
Sets the number of LVDS
lvds_num_bits
output bits
Advance LVDS data bits
lvds_advance and frame clock by one
clock cycle
Delay LVDS data bits and
lvds_delay
frame clock by one clock
cycle
fs_cntrl
Fine adjust ADC full scale
<5:0>
range
clk_freq
Input clock frequency
<1:0>
Address
In Hex
X
X
46
X
X
1
Nominal
X
X
X
50
Nominal
X
X
High z mode
X
12 bit
52
X
Inactive
0
X
Inactive
X
0
0% change
X
X
53
X
X
65 MHz
X
X
55
X
X
56
Description of Serial Registers
Software Reset
Name
Description
Default
rst
Self-clearing
software reset
Inactive
D15
D14
D13
D12
D11
D10
D9
D8
D7
D6
D5
D4
D3
D2
D1
0
D0
Address
In Hex
X
0
A / D Converters - SMT
Name
Setting the rst register bit to ‘1’, resets all internal registers including the rst register bit itself.
Power-Down Modes
Name
Description
Default
pd_ch
<8:1>
Channel-specific
power-down.
Inactive
sleep
Go to sleep-mode.
Inactive
pd
Go to power-down.
Inactive
pd_pin_cfg
<1:0>
Configures the PD
pin for sleep-modes.
PD pin configured
for power-down
mode
lvds_pd_mode
Controls LVDS
power down mode
High z mode
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
X
X
X
X
Address
In Hex
X
X
0F
X
X
X
X
52
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0 - 12
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
There are several ways to power down HMCAD1102, from sleep modes with short start up time to full power down with
extremely low power dissipation. There are two sleep modes, both with the LVDS clocks (FCLK, LCLK) running, such
that the synchronization with the receiver is maintained. The first is a light sleep mode (pd_ch<8:1>) with short start
up time, and the second a deep sleep mode (sleep) with the same start up time as full power down.
Setting pd_ch<n> = ‘1’, sets channel <n> of the ADC in sleep mode. This is a light sleep mode with short start up time.
Setting sleep = ‘1’, powers down all channels, but keeps FCLK and LCLK running to maintain LVDS synchronization.
The start up time is the same as for complete power down. Power consumption is significantly lower than for setting
pd_ch<8:1>=’FFhex’.
Setting pd = ‘1’ completely powers down the chip, including the band-gap reference circuit. Start-up time from this
mode is significantly longer than from the pd_ch<n> mode. The synchronization with the LVDS receiver is lost since
LCLK and FCLK outputs are put in high-Z mode.
A / D Converters - SMT
0
Setting pdn_pin_cfg<1:0> = ‘x1’ configures the circuit to enter sleep channel mode (all channels off) when the PD pin
is set high. This is equal to setting pd_ch<8:1>=’FFhex’. The channels can not be powered down separately using
the PD pin. Setting pdn_pin_cfg<1:0> = ‘10’ configures the circuit to enter (deep) sleep mode when PD pin is set high
(equal to setting sleep=’1’. When pdn_pin_cfg <1:0>= ‘00’, which is the default, the circuit enters power down mode
when the PD pin is set high.
The lvds_pd_mode register configures whether the LVDS data output drivers are powered down or kept alive in sleep
and sleep channel modes. LCLK and FCLK drivers are not affected by this register, and are always on in sleep and
sleep channel modes. If lvds_pd_mode is set low (default), the LVDS output is put in high Z mode, and the driver is
completely powered down. If lvds_pd_mode is set high, the LVDS output is set to constant 0, and the driver is still on
during sleep and sleep channel modes.
LVDS Drive Strength Programmability
Name
Description
Default
ilvds_lclk
<2:0>
LVDS current drive
programmability for LCLKP
and LCLKN pins.
3.5 mA drive
LVDS current drive
ilvds_frame
programmability for FCLKP
<2:0>
and FCLKN pins.
3.5 mA drive
LVDS current drive
programmability for output
data pins.
3.5 mA drive
ilvds_dat
<2:0>
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
X
X
X
X
Address
In Hex
X
11
X
The current delivered by the LVDS output drivers can be configured as shown in table 7. The default current is 3.5 mA,
which is what the LVDS standard specifies.
Setting the ilvds_lclk<2:0> register controls the current drive strength of the LVDS clock output on the LCLKP and
LCLKN pins.
Setting the ilvds_frame<2:0> register controls the current drive strength of the frame clock output on the FCLKP and
FCLKN pins.
Setting the ilvds_dat<2:0> register controls the current drive strength of the data outputs on the D[8:1]P and D[8:1]N
pins.
0 - 13
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Table 7: LVDS Output Drive
Strength for LCLK, FCLK and Data
LVDS drive strength
000
3.5 mA (default)
001
2.5 mA
010
1.5 mA
011
0.5 mA
100
7.5 mA
101
6.5 mA
110
5.5 mA
111
4.5 mA
LVDS Internal Termination Programmability
Address
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
In Hex
Name
Description
Default
en_lvds_
term
Enables internal termination
for LVDS buffers
Termination
disabled
X
Programmable termination for Termination
LCLKN and LCLKP buffers
disabled
1
term_frame Programmable termination for Termination
<2:0>
FCLKN and FCLKP buffers
disabled
1
term_lclk
<2:0>
term_dat
<2:0>
Programmable termination for Termination
DxP and DxN buffers
disabled
X
X
X
12
1
X
X
X
X
X
X
The off-chip load on the LVDS buffers may represent a characteristic impedance that is not perfectly matched with
the PCB traces. This may result in reflections back to the LVDS outputs and loss of signal integrity. This effect can be
mitigated by enabling an internal termination between the positive and negative outputs of each LVDS buffer. Internal
termination mode can be selected by setting the en_lvds_term bit to ‘1’. Once this bit is set, the internal termination
values for the bit clock, frame clock, and data buffers can be independently programmed using sets of three bits. Table
8 shows how the internal termination of the LVDS buffers are programmed. The values are typical values and can vary
by up to ±20% from device to device and across temperature.
Table 8: LVDS Output Internal
Termination for LCLK, FCLK and Data
term_*<2:0>
LVDS Internal Termination
0
Termination disabled
1
280Ω
10
165Ω
11
100Ω
100
125Ω
101
82Ω
110
67Ω
111
56Ω
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0
A / D Converters - SMT
ilvds_*<2:0>
0 - 14
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Analog Input Invert
Name
Description
Default
invert_ch
<8:1>
Swaps the polarity of
the analog input pins
IPx is
positive
input
D15
D14
D13 D12 D11 D10
D9
D8
D7
D6
D5
D4
D3
X
X
X
X
X
D2 D1 D0
X
X
Address
In Hex
X
24
The IPx pin represents the positive analog input pin, and INx represents the negative (complementary) input. Setting
the bits marked invert_ch<8:1> (individual control for each channel) causes the inputs to be swapped. INx would then
represent the positive input, and IPx the negative input.
LVDS Test Patterns
A / D Converters - SMT
0
Name
Description
Default
en_ramp
Enables a repeating fullscale ramp pattern on the
outputs
Inactive
X
0
0
Enables the mode wherein
dual_custom_
the output toggles between Inactive
pat
two defined codes
0
X
0
Enables the mode wherein
the output is a constant
Inactive
specified code
0
0
X
single_
custom_pat
bits_custom1
<13:0>
Bits for the single custom
pattern and for the first
code of the dual custom
pattern. <0> is the LSB
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
Address
In Hex
25
Inactive
X
X
X
X
X
X
X
X
X
X
X
X
X
X
26
bits_custom2 Bits for the second code of
Inactive
<13:0>
the dual custom pattern
X
X
X
X
X
X
X
X
X
X
X
X
X
X
27
pat_deskew
pat_sync
Enables deskew pattern
mode
Inactive
0
X
Enables sync pattern mode Inactive
X
0
45
To ease the LVDS synchronization setup of HMCAD1102, several test patterns can be set up on the outputs.
Normal ADC data are replaced by the test pattern in these modes. Setting en_ramp to ‘1’ sets up a repeating full-scale
ramp pattern on all data outputs. The ramp starts at code zero and is increased 1LSB every clock cycle. It returns to
zero code and starts the ramp again after reaching the full-scale code.
A constant value can be set up on the outputs by setting single_custom_pat to ‘1’, and programming the desired value
in bits_custom1<13:0>. In this mode, bits_custom1<13:0> replaces the ADC data at the output, and is controlled by
LSB-first and MSB-first modes in the same way as normal ADC data are.
The device may also be made to alternate between two codes by programming dual_custom_pat to ‘1’. The two codes
are the contents of bits_custom1<13:0> and bits_custom2<13:0>. Two preset patterns can also be selected:
1. Deskew pattern: Set using pat_deskew, this mode replaces the ADC output with ‘01010101010101’ (two
LSBs removed in 12 bit mode).
2. Sync pattern: Set using pat_sync, the normal ADC word is replaced by a fixed ‘11111110000000’ word
(‘111111000000’ in 12 bit mode)
Note: Only one of the above patterns should be selected at the same time.
0 - 15
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Programmable Gain
Name
Description
Default
D15 D14 D13 D12 D11 D10
gain_ch1
<3:0>
Programmable gain
for channel 1
0 dB gain
gain_ch2
<3:0>
Programmable gain
for channel 2
0 dB gain
gain_ch3
<3:0>
Programmable gain
for channel 3
0 dB gain
gain_ch4
<3:0>
Programmable gain
for channel 4
0 dB gain
X
X
X
X
gain_ch5
<3:0>
Programmable gain
for channel 5
0 dB gain
X
X
X
X
gain_ch6
<3:0>
Programmable gain
for channel 6
0 dB gain
gain_ch7
<3:0>
Programmable gain
for channel 7
0 dB gain
gain_ch8
<3:0>
Programmable gain
for channel 8
0 dB gain
D9
D8
D7
D6
D5
D4
D3
X
X
X
X
D2 D1 D0
X
X
Address
In Hex
X
X
2A
X
X
X
X
X
X
X
2B
X
X
X
X
X
X
X
X
HMCAD1102 includes a purely digital programmable gain option in addition to the Full-scale Control. The programmable
gain of each channel can be individually set using four bits, indicated as gain_chx<3:0> for Channel x. The gain
setting is coded in binary from 0 dB to 12 dB, as shown in Table 9.
Table 9: Gain setting for channels 1-8
gain_chx <3:0>
Channel x Gain Setting
0000
0 dB
0001
1 dB
0010
2 dB
0011
3 dB
0100
4 dB
0101
5 dB
0110
6 dB
0111
7 dB
1000
8 dB
1001
9 dB
1010
10 dB
1011
11 dB
1100
12 dB
1101
Do not use
1110
Do not use
1111
Do not use
0
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
A / D Converters - SMT
X
0 - 16
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
LVDS Clock Programmability and Data Output Modes
Name
Description
Default
phase_ddr
<1:0>
Controls the phase of LCLK
output relative to data.
90 degrees.
btc_mode
A / D Converters - SMT
0
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
X
X
42
Binary two’s complement format Straight offset
for ADC output data.
binary.
msb_first
Serialized ADC output data
comes out with MSB first.
LSB-first
output.
en_sdr
Enable SDR output mode. LCLK
becomes a 12X input clock.
DDR output
mode.
fall_sdr
Rising edge of
Controls whether the LCLK rising
LCLK comes
or falling edge comes in the
in the middle
middle of the data window when
of the data
operating in SDR mode.
window.
Address
In Hex
X
X
X
X
46
1
The output interface of HMCAD1102 is normally a DDR interface, with the LCLK rising and falling edge transitions
in the middle of alternate data windows. The phase for LCLK can be programmed relative to the output frame clock
and data bits using phase_ddr<1:0>. The LCLK phase modes are shown in figure 9. The default timing is identical to
setting phase_ddr<1:0>=’10’.
PHASE_DDR<1:0>='00' (270 deg)
FCLKN
FCLKP
LCLKP
LCLKN
Dxx<1:0>
PHASE_DDR<1:0>='10' (90 deg)
FCLKN
FCLKP
LCLKN
LCLKP
Dxx<1:0>
PHASE_DDR<1:0>='01' (180 deg)
FCLKN
FCLKP
LCLKN
LCLKP
Dxx<1:0>
PHASE_DDR<1:0>='11' (0 deg)
FCLKN
FCLKP
LCLKP
LCLKN
Dxx<1:0>
Figure 8. Phase programmability modes for LCLK
The device can also be made to operate in SDR mode by setting the en_sdr bit to ‘1’. The bit clock (LCLK) is output
at 12x times the input clock in this mode, two times the rate in DDR mode. Depending on the state of fall_sdr, LCLK
may be output in either of the two manners shown in Figure 10. As can be seen in Figure 10, only the LCLK rising (or
falling) edge is used to capture the output data in SDR mode. The SDR mode is not recommended beyond 40 MSPS
because the LCLK frequency becomes very high.
0 - 17
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
EN_SDR='1', FALL_SDR_'0'
FCLKN
FCLKP
LCLKP
LCLKN
Dxx<1:0>
EN_SDR='1', FALL_SDR_'1'
FCLKN
FCLKP
LCLKN
LCLKP
Dxx<1:0>
Figure 9. SDR interface modes
The default data output format is offset binary. Two’s complement mode can be selected by setting the btc_mode bit
to ‘1’ which inverts the MSB.
The first bit of the frame (following the rising edge of FCLKP) is the LSB of the ADC output for default settings.
Programming the msb_first mode results in reverse bit order, and the MSB is output as the first bit following the
FCLKP rising edge.
0
Name
Description
Default D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0
lvds_num_bits
Sets the number of LVDS
output bits
12 bit
lvds_advance
Advance LVDS data bits
and frame clock by one
clock cycle
Inactive
0
X
lvds_delay
Delay LVDS data bits and
frame clock by one clock
cycle
Inactive
X
0
Address
In Hex
X
53
The ADC channels have 13 bits of resolution. There are two options for the serial LVDS outputs, 12 bits or 14 bits,
selected by setting lvds_num_bits to ‘0’ or ‘1’, respectively. In 12 bits mode, the LSB bit from the ADCs are removed
in the output stream. In 14 bit mode, a ‘0’ is added in the LSB position. Power down mode must be activated after or
during a change in the number of output bits.
To ease timing in the receiver when using multiple ADC chips, HMCAD1102 has the option to adjust the timing of the
output data and the frame clock. The propagation delay with respect to the ADC input clock can be moved one LVDS
clock cycle forward or backward, by using lvds_delay and lvds_advance, respectively. See figure 11 for details. Note
that LCLK is not affected by lvds_delay or lvds_advance settings.
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
A / D Converters - SMT
Number of Serial Output Bits and LVDS output timing
0 - 18
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
ADC clock
TLVDS
LCLKP
LCLKN
TPROP
FCLKP
FCLKN
default:
Dxx<1:0>
D3 D4 D5 D6 D7 D8 D9 D10 D11 D0
N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N
TPROP
A / D Converters - SMT
0
lvds_delay = '1':
D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D0
N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N
D3
N
D4
N
D5
N
D6
N
D7
N
D8
N
D9
N
D1
N
D2
N
D3
N
D4
N
D5
N
D6
N
D7
N
D8
N
D3
N
D4
N
D5
N
D6
N
D7
N
D8
N
D9
N
D10
N
D5
D4
D3
X
X
X
TLVDS
TPROP
lvds_advance = '1':
D2
N
TLVDS
FCLKP
FCLKN
Dxx<1:0>
D1
N
FCLKP
FCLKN
Dxx<1:0>
D4 D5 D6 D7 D8 D9 D10 D11 D0
N-1 N-1 N-1 N-1 N-1 N-1 N-1 N-1 N
D1
N
D2
N
Figure 10. LVDS output timing adjustment
Full-Scale Control
Name
Description
Default
fs_cntrl
<5:0>
Fine adjust ADC full
scale range
0%
change
D15
D14
D13 D12 D11 D10
D9
D8
D7
D6
D2 D1 D0
X
X
X
Address
In Hex
55
The full-scale voltage range of HMCAD1102 can be adjusted using an internal 6-bit DAC controlled by the fs_cntrl
register. Changing the value in the register by one step, adjusts the full-scale range by approximately 0.3%. This
leads to a maximum range of ±10% adjustment. Table 10 shows how the register settings correspond to the full-scale
range. Note that the values for full-scale range adjustment are approximate. The DAC is, however, guaranteed to be
monotonous.
The full-scale control and the programmable gain features differ in two major ways:
1. The full-scale control feature controls the full-scale voltage range in an analog fashion, whereas the
programmable gain is a digital feature.
2. The programmable gain feature has much coarser gain steps and larger range than the full-scale control.
0 - 19
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Table 10: Register Values with
Corresponding Change in Full-Scale Range
Full-scale range adjustment
111111
9.70%
111110
9.40%
100001
0.30%
100000
0%
011111
−0.3%
000001
−9.7%
000000
−10%
To optimize start up time, a register is provided where the input clock frequency can be set. Some internal circuitry
have start up times that are clock frequency independent. Default counter values are set to accommodate these start
up times at the maximum clock frequency. This will lead to increased start up times at low clock frequency. Setting
the value of this register to the nearest higher clock frequency will reduce the count values of the internal counters,
to better fit the actual start up time, such that the start up time will be reduced. The start up times from Power Down
mode and Deep Sleep mode are changed by this register setting.
Table 11: Clock frequency settings
clk_freq
<1:0>
Clock frequency
range
Startup delay
(clock cycles)
Startup delay (µs)
0
0
50 - 80 MHz
992
12.4 - 19.8
0
1
32.5 - 50 MHz
640
12.8 - 19.7
1
0
20 - 32.5 MHz
420
12.9 - 21
1
1
15 - 20 MHz
260
13 - 17.3
Performance Control
Name
Description
Default
perfm_cntrl
<2:0>
ADC performance
control
Nominal
ext_vcm_bc
<1:0>
VCM buffer driving
strength control
Nominal
D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2 D1 D0
X
X
Address
In Hex
X
50
X
X
0
A / D Converters - SMT
fs_cntrl<5:0>
There are two registers that impact performance and power dissipation.
The perfm_cntrl register adjusts the performance level of the ADC core. If full performance is required, the nominal
setting must be used. The lowest code can be used in situations where power dissipation is critical and performance
is less important. For most conditions the performance at the minimum setting will be similar to nominal setting.
However, only 11 bit performance can be expected at worst case conditions. The power dissipation savings shown in
table 12 are only approximate numbers for the ADC current alone.
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0 - 20
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Table 12: Performance Control Settings
A / D Converters - SMT
0
perfm_cntrl<2:0>
Analog power dissipation
100
-40% (lower performance)
101
-30%
110
-20%
111
-10%
000 (default)
Nominal
001
Do not use
010
Do not use
011
Do not use
The ext_vcm_bc register controls the driving strength in the buffer supplying the voltage on the VCM pin. If this pin is
not in use, the buffer can be switched off. If current is drawn from the VCM pin, the driving strength can be increased
to keep the voltage on this pin at the correct level.
Table 13: External Common
Mode Voltage Buffer Driving Strength
ext_vcm_bc
<1:0>
VCM buffer driving strength [µA] Max current
sinked/sourced from VCM pin with < 50 mV
voltage change.
00
Off (VCM floating)
01 (default)
±6.5
10
±70
11
±140
Theory of Operation
HMCAD1102 is an 8-channel, high-speed, CMOS
ADC. The outputs from each channel are serialized
to 12 or 14 bits and sent out on a single pair of pins
in LVDS format. All eight channels of HMCAD1102
operate from one clock input, which can be differential
or single ended. The sampling clocks for each of the
eight channels are generated from the clock input
using a carefully matched clock buffer tree. The 12x
clock required for the serializer is generated internally
from FCLK using a phase-locked loop (PLL). A 6x and
1x clock are also output in LVDS format, along with
the data to enable easy data capture. HMCAD1102
uses internally generated references. The differential
reference value is 1V. This results in a differential input
of −1V to correspond to the zero code of the ADC, and
a differential input of +1V to correspond to the fullscale code (code 8191).
HMCAD1102 operates from two sets of supplies
and grounds. The analog supply and ground set is
identified as AVDD and AVSS, while the digital set is
identified by DVDD and DVSS.
Recommended Usage
Analog Input
The analog input to HMCAD1102 is a switched
capacitor track-and-hold amplifier optimized for
differential operation. Operation at common mode
voltages at mid supply is recommended even if
performance will be good for the ranges specified.
The VCM pin provides a voltage suitable as common
mode voltage reference. The internal buffer for
the VCM voltage can be switched off, and driving
capabilities can be changed programming the ext_
vcm_bc<1:0> register.
The ADC employs a pipelined converter architecture.
Each stage feeds its output data into the digital error
correction logic, ensuring excellent differential linearity
and no missing codes at 12-bit level.
0 - 21
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
AC-Coupling
Figure 12 shows a simplified drawing of the input
network. The signal source must have sufficiently low
output impedance to charge the sampling capacitors
within one clock cycle. A small external resistor (e.g.
22 Ohm) in series with each input is recommended
as it helps reducing transient currents and dampens
ringing behavior. A small differential shunt capacitor
at the chip side of the resistors may be used to
provide dynamic charging currents and may improve
performance. The resistors form a low pass filter
with the capacitor, and values must therefore be
determined by requirements for the application.
DC-Coupling
Figure 13 shows a recommended configuration for
DC-coupling. Note that the common mode input
voltage must be controlled according to specified
values. Preferably, the CM_EXT output should be
used as reference to set the common mode voltage.
Figure 13. Transformer coupled input
If the input signal is traveling a long physical distance
from the signal source to the transformer (for example
a long cable), kick-backs from the ADC will also
travel along this distance. If these kick-backs are
not terminated properly at the source side, they are
reflected and will add to the input signal at the ADC
input. This could reduce the ADC performance. To
avoid this effect, the source must effectively terminate
the ADC kick-backs, or the traveling distance should
be very short. If this problem could not be avoided, the
circuit in figure 16 can be used.
0
A / D Converters - SMT
Figure 11. Input configuration
A signal transformer or series capacitors can be
used to make an AC-coupled input network. Figure
14 shows a recommended configuration using a
transformer. Make sure that a transformer with
sufficient linearity is selected, and that the bandwidth
of the transformer is appropriate. The bandwidth
should exceed the sampling rate of the ADC with at
least a factor of 10. It is also important to minimize
phase mismatch between the differential ADC inputs
for good HD2 performance. This type of transformer
coupled input is the preferred configuration for high
frequency signals as most differential amplifiers do
not have adequate performance at high frequencies.
Magnetic coupling between the transformers and PCB
traces may impact channel crosstalk, and must hence
be taken into account during PCB layout.
Figure 12. DC coupled input
The input amplifier could be inside a companion chip
or it could be a dedicated amplifier. Several suitable
single ended to differential driver amplifiers exist in the
market. The system designer should make sure the
specifications of the selected amplifier is adequate for
the total system, and that driving capabilities comply
with HMCAD1102 input specifications.
Figure 14. AC coupled input
Detailed configuration and usage instructions must be
found in the documentation of the selected driver, and
the values given in figure 13 must be varied according
to the recommendations for the driver.
Figure 15 shows AC-coupling using capacitors.
Resistors from the CM_EXT output, RCM, should be
used to bias the differential input signals to the correct
voltage. The series capacitor, CI, form the high-
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0 - 22
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
pass pole with these resistors, and the values must
therefore be determined based on the requirement to
the high-pass cut-off frequency.
Note that Start Up Time from Sleep Mode and Power
Down Mode will be affected by this filter as the time
required to charge the series capacitors is dependent
on the filter cut-off frequency.
A / D Converters - SMT
0
0 - 23
If the input signal has a long traveling distance, and the
kick-backs from the ADC are not effectively terminated
at the signal source, the input network of figure 16 can
be used. The configuration in figure 16 is designed to
attenuate the kickback from the ADC and to provide
an input impedance that looks as resistive as possible
for frequencies below Nyquist.
Figure 15. Alternative input network
Values of the series inductor will however depend on
board design and conversion rate. In some instances
a shunt capacitor in parallel with the termination
resistor (e.g. 33pF) may improve ADC performance
further. This capacitor attenuate the ADC kick-back
even more, and minimize the kicks traveling towards
the source. However, the impedance match seen into
the transformer becomes worse.
Clock Input and Jitter Considerations
Typically high-speed ADCs use both clock edges to
generate internal timing signals. In HMCAD1102 only
the rising edge of the clock is used. Hence, input clock
duty cycles between 20% and 80% are acceptable.
The input clock can be supplied in a variety of formats.
The clock pins are AC-coupled internally, hence a wide
common mode voltage range is accepted. Differential
clock sources such as LVDS, LVPECL or differential
sine wave can be connected directly to the input pins.
For CMOS inputs, the CLKN pin should be connected
to ground, and the CMOS clock signal should be
connected to CLKP. For differential sine wave clock
input the amplitude must be at least ± 0.8 Vpp. No
additional configuration is needed to set up the clock
source format.
The quality of the input clock is extremely important for
high-speed, high-resolution ADCs. The contribution to
SNR from clock jitter with a full scale signal at a given
frequency is shown in equation 1.
SNRjitter = 20 · log (2 · π · ƒIN · єt)
(1)
where fIN is the signal frequency, and εt is the total
rms jitter measured in seconds. The rms jitter is the
total of all jitter sources including the clock generation
circuitry, clock distribution and internal ADC circuitry.
For applications where jitter may limit the obtainable
performance, it is of utmost importance to limit the clock
jitter. This can be obtained by using precise and stable
clock references (e.g. crystal oscillators with good jitter
specifications) and make sure the clock distribution
is well controlled. It might be advantageous to use
analog power and ground planes to ensure low noise
on the supplies to all circuitry in the clock distribution.
It is of utmost importance to avoid crosstalk between
the ADC output bits and the clock and between the
analog input signal and the clock since such crosstalk
often results in harmonic distortion.
The jitter performance is improved with reduced rise
and fall times of the input clock. Hence, optimum jitter
performance is obtained with LVDS or LVPECL clock
with fast edges. CMOS and sine wave clock inputs will
result in slightly degraded jitter performance.
If the clock is generated by other circuitry, it should
be re-timed with a low jitter master clock as the last
operation before it is applied to the ADC clock input.
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
HMCAD1102
v03.0611
Octal 12-Bit 80 MSPS
A/D Converter
Outline Drawing
Table 14: Dimensions
Symbol
Millimeter
Min
Typ
A
A1
Inch
Max
Typ
0.9
0.01
0.05
A2
0.65
0.7
A3
0.2 REF.
b
Min
0
0.2
D
0.25
0
0.0004
0.002
0.026
0.028
0.008 REF.
0.3
0.008
9.00 bsc
D1
Max
0.035
0.01
0.012
0.354 bsc
8.75 bsc
0.344 bsc
D2
5
5.2
5.4
0.197
0.205
0.213
L
0.3
0.4
0.5
0.012
0.016
0.02
e
0.50 bsc
Θ1
0°
F
1.3
G
0.24
A / D Converters - SMT
0
0.020 bsc
12°
0°
12°
0.05
0.42
0.6
0.0096
0.0168
0.024
Package Information
Part Number
Package Body Material
Lead Finish
MSL [1]
Package Marking [2]
HMCAD1102
RoHS-compliant Low Stress Injection Molded Plastic
100% matte Sn
Level 2A
HAD1102
XXXX
[1] MSL, Peak Temp: The moisture sensitivity level rating classified according to the JEDEC industry standard and to peak solder temperature.
[2] Proprietary marking XXXX, 4-Digit lot number XXXX
For price, delivery and to place orders: Hittite Microwave Corporation, 2 Elizabeth Drive, Chelmsford, MA 01824
978-250-3343 tel • 978-250-3373 fax • Order On-line at www.hittite.com
Application Support: [email protected]
0 - 24