Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsData collecting ICsData acquisition IC - AD converter (ADC) External , Internal QFN 52

LTC2172-12/

LTC2171-12/LTC2170-12

21721012fb

Typical applicaTion

DescripTion

12-Bit, 65Msps/40Msps/

25Msps Low Power Quad ADCs

The LTC

2172-12/LTC2171-12/LTC2170-12 are 4-channel,

simultaneous sampling 12-bit A/D converters designed for

digitizing high frequency, wide dynamic range signals. They

are perfect for demanding communications applications

with AC performance that includes 71dB SNR and 90dB

spurious free dynamic range (SFDR). An ultralow jitter of

0.15ps

RMS

allows undersampling of IF frequencies with

excellent noise performance.

DC specifications include ±0.3LSB INL (typ), ±0.1LSB

DNL (typ) and no missing codes over temperature. The

transition noise is a low 0.3LSB

RMS

The digital outputs are serial LVDS to minimize the num-

ber of data lines. Each channel outputs two bits at a time

(2-lane mode) or one bit at a time (1-lane mode). The LVDS

drivers have optional internal termination and adjustable

output levels to ensure clean signal integrity.

The ENC

and ENC

–

inputs may be driven differentially

or single-ended with a sine wave, PECL, LVDS, TTL or

CMOS inputs. An internal clock duty cycle stabilizer al-

lows high performance at full speed for a wide range of

clock duty cycles.

LTC2172-12, 65Msps,

2-Tone FFT, f

= 70MHz and 75MHz

FeaTures

applicaTions

4-Channel Simultaneous Sampling ADC

71dB SNR

90dB SFDR

Low Power: 306mW/198mW/160mW Total,

77mW/50mW/40mW per Channel

Single 1.8V Supply

Serial LVDS Outputs: One or Tw o Bits per Channel

Selectable Input Ranges: 1V

P-P

to 2V

P-P

800MHz Full Power Bandwidth Sample-and-Hold

Shutdown and Nap Modes

Serial SPI Port for Configuration

Pin-Compatible 14-Bit and 12-Bit Versions

52-Pin (7mm × 8mm) QFN Package

Communications

Cellular Base Stations

Software Defined Radios

Portable Medical Imaging

Multichannel Data Acquisition

Nondestructive Testing

DATA

SERIALIZER

ENCODE

INPUT

SERIALIZED

LVDS

OUTPUTS

1.8V

OUT1A

OUT1B

OUT2A

OUT2B

OUT3A

OUT3B

OUT4A

OUT4B

DATA

CLOCK

OUT

FRAME

OGND

GND

217212 TA01

S/H

CHANNEL 1

ANALOG

INPUT

12-BIT

ADC CORE

S/H

CHANNEL 2

ANALOG

INPUT

12-BIT

ADC CORE

S/H

CHANNEL 3

ANALOG

INPUT

12-BIT

ADC CORE

S/H

CHANNEL 4

ANALOG

INPUT

12-BIT

ADC CORE

PLL

FREQUENCY (MHz)

–100

–110

–120

–70

–60

–80

–90

AMPLITUDE (dBFS)

–50

–30

–40

–20

–10

20 30

217212 TA01b

L, LT, LT C , LT M, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

Summary of content (34 pages)

PAGE 1
LTC2172-12/ LTC2171-12/LTC2170-12 12-Bit, 65Msps/40Msps/ 25Msps Low Power Quad ADCs Description Features n n n n n n n n n n n n 4-Channel Simultaneous Sampling ADC 71dB SNR 90dB SFDR Low Power: 306mW/198mW/160mW Total, 77mW/50mW/40mW per Channel Single 1.
PAGE 2
LTC2172-12/ LTC2171-12/LTC2170-12 Absolute Maximum Ratings Pin Configuration (Notes 1 and 2) OUT1B– OUT1B+ OUT1A– OUT1A+ GND SDO PAR/SER VREF GND SENSE VDD TOP VIEW VDD Supply Voltages VDD , OVDD............................................... –0.3V to 2V Analog Input Voltage (AIN +, AIN –, PAR/SER, SENSE) (Note 3)........... –0.3V to (VDD + 0.2V) Digital Input Voltage (ENC+, ENC–, CS, SDI, SCK) (Note 4)..................................... –0.3V to 3.9V SDO (Note 4)...........................
PAGE 3
LTC2172-12/ LTC2171-12/LTC2170-12 Converter Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) LTC2172-12 PARAMETER CONDITIONS MIN LTC2171-12 TYP MAX MIN LTC2170-12 TYP MAX MIN MAX UNITS l 12 Integral Linearity Error Differential Analog Input (Note 6) l –1 ±0.3 1 –1 ±0.3 1 –1 ±0.3 1 LSB Differential Linearity Error Differential Analog Input l –0.5 ±0.1 0.5 –0.4 ±0.1 0.
PAGE 4
LTC2172-12/ LTC2171-12/LTC2170-12 Dynamic Accuracy The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. AIN = –1dBFS.
PAGE 5
LTC2172-12/ LTC2171-12/LTC2170-12 Digital Inputs And Outputs The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 5) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS ENCODE INPUTS (ENC+, ENC– ) Differential Encode Mode (ENC– Not Tied to GND) VID Differential Input Voltage (Note 8) VICM Common Mode Input Voltage Internally Set Externally Set (Note 8) l 1.1 l 0.
PAGE 6
LTC2172-12/ LTC2171-12/LTC2170-12 Power Requirements The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 9) LTC2172-12 SYMBOL PARAMETER CONDITIONS LTC2171-12 LTC2170-12 MIN TYP MAX MIN TYP MAX MIN TYP MAX UNITS VDD Analog Supply Voltage (Note 10) l 1.7 1.8 1.9 1.7 1.8 1.9 1.7 1.8 1.9 V OVDD Output Supply Voltage (Note 10) l 1.7 1.8 1.9 1.7 1.8 1.9 1.7 1.8 1.
PAGE 7
LTC2172-12/ LTC2171-12/LTC2170-12 Timing Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
PAGE 8
LTC2172-12/ LTC2171-12/LTC2170-12 Timing Diagrams 2-Lane Output Mode, 16-Bit Serialization tAP ANALOG INPUT N+1 N tENCH tENCL ENC– ENC+ tSER DCO– DCO+ tDATA tFRAME FR– FR+ tSER tPD tSER OUT#A– OUT#A+ OUT#B– OUT#B+ D3 D1 DX* 0 D11 D9 D7 D5 D3 D1 DX* 0 D11 D9 D2 D0 DY* 0 D10 D8 D6 D4 D2 D0 DY* 0 D10 D8 SAMPLE N-6 SAMPLE N-5 D7 D6 217212 TD01 SAMPLE N-4 *DX AND DY ARE EXTRA NON-DATA BITS FOR COMPLETE SOFTWARE COMPATIBILITY WITH THE 14-BIT VERSIONS OF THESE A/Ds.
PAGE 9
LTC2172-12/ LTC2171-12/LTC2170-12 timing DIAGRAMS 2-Lane Output Mode, 12-Bit Serialization tAP ANALOG INPUT N+1 N tENCH tENCL ENC– ENC+ tSER DCO– DCO+ tDATA tFRAME FR+ FR– tPD tSER OUT#A– OUT#A+ OUT#B– OUT#B+ tSER D7 D5 D3 D1 D11 D9 D7 D5 D3 D1 D11 D9 D7 D6 D4 D2 D0 D10 D8 D6 D4 D2 D0 D10 D8 D6 SAMPLE N-6 SAMPLE N-5 217212 TD03 SAMPLE N-4 1-Lane Output Mode, 16-Bit Serialization tAP ANALOG INPUT N+1 N tENCH tENCL ENC– ENC+ tSER DCO– DCO+ tFRAME FR– FR+ t
PAGE 10
LTC2172-12/ LTC2171-12/LTC2170-12 timing DIAGRAMS 1-Lane Output Mode, 14-Bit Serialization tAP ANALOG INPUT N+1 N tENCH tENCL ENC– ENC+ tSER DCO– DCO+ tFRAME FR– FR+ OUT#A– OUT#A+ tDATA tSER tPD D1 D0 DX* tSER DY* D11 SAMPLE N-6 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 DX* DY* SAMPLE N-5 D11 D10 D9 D8 217212 TD05 SAMPLE N-4 OUT#B+, OUT#B– ARE DISABLED *DX AND DY ARE EXTRA NON-DATA BITS FOR COMPLETE SOFTWARE COMPATIBILITY WITH THE 14-BIT VERSIONS OF THESE A/Ds.
PAGE 11
LTC2172-12/ LTC2171-12/LTC2170-12 timing DIAGRAMS SPI Port Timing (Readback Mode) tDS tS tDH tSCK tH CS SCK tDO SDI SDO R/W A6 A5 A4 A3 A2 A1 A0 XX D7 HIGH IMPEDANCE XX D6 XX D5 XX D4 XX D3 XX D2 XX XX D1 D0 SPI Port Timing (Write Mode) CS SCK SDI SDO R/W HIGH IMPEDANCE A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0 217212 TD07 21721012fb 11
PAGE 12
LTC2172-12/ LTC2171-12/LTC2170-12 Typical Performance Characteristics LTC2172-12: Differential Nonlinearity (DNL) 1.0 1.0 0 0.8 0.8 –10 0.6 0.6 0.4 0.4 0.2 0 –0.2 –0.4 0 –0.2 –0.4 –0.6 –0.8 –0.8 –1.0 –1.0 0 1024 2048 3072 OUTPUT CODE 4096 –30 0.2 –0.
PAGE 13
LTC2172-12/ LTC2171-12/LTC2170-12 Typical Performance Characteristics LTC2172-12: SFDR vs Input Frequency, –1dBFS, 2V Range, 65Msps 110 100 85 80 75 80 70 dBc 60 60 50 40 30 50 30 20 10 10 0 50 100 150 200 250 300 INPUT FREQUENCY (MHz) 0 –80 –70 –60 –50 –40 –30 –20 –10 INPUT LEVEL (dBFS) 350 LTC2172-12: IVDD vs Sample Rate, 5MHz Sine Wave Input, –1dBFS 155 2-LANE, 3.5mA 40 150 145 IOVDD (mA) 130 –10 70 2-LANE, 1.75mA 20 69 68 125 1-LANE, 1.75mA 10 120 71 1-LANE, 3.
PAGE 14
LTC2172-12/ LTC2171-12/LTC2170-12 Typical Performance Characteristics 0 LTC2171-12: 8k Point FFT, fIN = 69MHz, –1dBFS, 40Msps 0 –10 –10 –20 –20 –20 –30 –30 –30 –40 –50 –60 –70 –80 AMPLITUDE (dBFS) –10 AMPLITUDE (dBFS) AMPLITUDE (dBFS) 0 LTC2171-12: 8k Point FFT, fIN = 29MHz, –1dBFS, 40Msps –40 –50 –60 –70 –80 –40 –50 –60 –70 –80 –90 –100 –90 –100 –90 –100 –110 –120 –110 –120 –110 –120 0 20 10 FREQUENCY (MHz) 0 217212 G24 0 14000 –40 12000 –60 –70 71 70 SNR (dBFS) –30 CO
PAGE 15
LTC2172-12/ LTC2171-12/LTC2170-12 Typical Performance Characteristics LTC2170-12: Integral Nonlinearity (INL) 72 71 INL ERROR (LSB) SNR (dBFS) 70 69 68 67 66 0.6 0.7 0.8 0.9 1 1.1 SENSE PIN (V) 1.2 1.0 1.0 0.8 0.8 0.6 0.6 0.4 0.4 0.2 0 –0.2 –0.4 –0.2 –0.4 –0.6 –0.8 0 1024 2048 3072 OUTPUT CODE –1.
PAGE 16
LTC2172-12/ LTC2171-12/LTC2170-12 Typical Performance Characteristics LTC2170-12: SFDR vs Input Frequency, –1dBFS, 2V Range, 25Msps LTC2170-12: SNR vs Input Frequency, –1dBFS, 2V Range, 25Msps 72 95 71 90 70 85 110 LTC2170-12: SFDR vs Input Level, fIN = 70MHz, 2V Range, 25Msps 69 68 80 75 67 70 66 65 dBFS 90 SFDR (dBc AND dBFS) SFDR (dBFS) SNR (dBFS) 100 80 70 dBc 60 50 40 30 20 10 0 100 150 200 250 300 INPUT FREQUENCY (MHz) 50 350 0 50 100 150 200 250 300 INPUT FREQUENCY (MHz)
PAGE 17
LTC2172-12/ LTC2171-12/LTC2170-12 Pin Functions AIN1+ (Pin 1): Channel 1 Positive Differential Analog Input. ENC– (Pin 18): Encode Complement Input. Conversion starts on the falling edge. AIN1– (Pin 2): Channel 1 Negative Differential Analog Input. CS (Pin 19): In serial programming mode (PAR/SER = 0V), CS is the serial interface chip select input. When CS is low, SCK is enabled for shifting data on SDI into the mode control registers.
PAGE 18
LTC2172-12/ LTC2171-12/LTC2170-12 Pin Functions PAR/SER (Pin 47): Programming Mode Selection Pin. Connect to ground to enable serial programming mode. CS, SCK, SDI and SDO become a serial interface that controls the A/D operating modes. Connect to VDD to enable parallel programming mode where CS, SCK, SDI and SDO become parallel logic inputs that control a reduced set of the A/D operating modes. PAR/SER should be connected directly to ground or the VDD of the part and not be driven by a logic signal.
PAGE 19
LTC2172-12/ LTC2171-12/LTC2170-12 Functional Block Diagram ENC+ ENC– 1.8V 1.8V VDD CHANNEL 1 ANALOG INPUT SAMPLEAND-HOLD 12-BIT ADC CORE CHANNEL 2 ANALOG INPUT SAMPLEAND-HOLD 12-BIT ADC CORE OVDD OUT1A PLL OUT1B OUT2A OUT2B DATA SERIALIZER CHANNEL 3 ANALOG INPUT OUT3A 12-BIT ADC CORE SAMPLEAND-HOLD OUT3B OUT4A CHANNEL 4 ANALOG INPUT VREF 1µF SAMPLEAND-HOLD 12-BIT ADC CORE OUT4B DATA CLOCK OUT 1.
PAGE 20
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information CONVERTER OPERATION The LTC2172-12/LTC2171-12/LTC2170-12 are low power, 4-channel, 12-bit, 65Msps/40Msps/25Msps A/D converters that are powered by a single 1.8V supply. The analog inputs should be driven differentially. The encode input can be driven differentially for optimal jitter performance, or single-ended for lower power consumption. The digital outputs are serial LVDS to minimize the number of data lines.
PAGE 21
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information Transformer Coupled Circuits Amplifier Circuits Figure 3 shows the analog input being driven by an RF transformer with a center-tapped secondary. The center tap is biased with VCM, setting the A/D input at its optimal DC level. At higher input frequencies a transmission line balun transformer (Figures 4 to 6) has better balance, resulting in lower A/D distortion. Figure 7 shows the analog input being driven by a high speed differential amplifier.
PAGE 22
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information Reference Encode Input The LTC2172-12/LTC2171-12/LTC2170-12 has an internal 1.25V voltage reference. For a 2V input range using the internal reference, connect SENSE to VDD. For a 1V input range using the internal reference, connect SENSE to ground. For a 2V input range with an external reference, apply a 1.25V reference voltage to SENSE (Figure 9). The signal quality of the encode inputs strongly affects the A/D noise performance.
PAGE 23
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information The differential encode mode is recommended for sinusoidal, PECL, or LVDS encode inputs (Figures 12 and 13). The encode inputs are internally biased to 1.2V through 10k equivalent resistance. The encode inputs can be taken above VDD (up to 3.6V), and the common mode range is from 1.1V to 1.6V. In the differential encode mode, ENC – should stay at least 200mV above ground to avoid falsely triggering the single-ended encode mode.
PAGE 24
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information Table 1. Maximum Sampling Frequency for All Serialization Modes. Note That These Limits Are for the LTC2172-12. The Sampling Frequency for the Slower Speed Grades Cannot Exceed 40MHz (LTC2171-12) or 25MHz (LTC2170-12). SERIALIZATION MODE MAXIMUM SAMPLING FREQUENCY, fS (MHz) DCO FREQUENCY FR FREQUENCY SERIAL DATA RATE 2-Lane 16-Bit Serialization 65 4 • fS fS 8 • fS 2-Lane 14-Bit Serialization 65 3.5 • fS 0.
PAGE 25
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information Digital Output Randomizer Interference from the A/D digital outputs is sometimes unavoidable. Digital interference may be from capacitive or inductive coupling or coupling through the ground plane. Even a tiny coupling factor can cause unwanted tones in the ADC output spectrum. These unwanted tones can be randomized by randomizing the digital output before it is transmitted off chip, which reduces the unwanted tone amplitude.
PAGE 26
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information Serial Programming Mode To use the serial programming mode, PAR/SER should be tied to ground. The CS, SCK, SDI and SDO pins become a serial interface that program the A/D mode control registers. Data is written to a register with a 16-bit serial word. Data can also be read back from a register to verify its contents. Serial data transfer starts when CS is taken low. The data on the SDI pin is latched at the first 16 rising edges of SCK.
PAGE 27
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information REGISTER A2: OUTPUT MODE REGISTER (ADDRESS 02h) D7 ILVDS2 D6 D5 D4 D3 D2 D1 D0 ILVDS1 ILVDS0 TERMON OUTOFF OUTMODE2 OUTMODE1 OUTMODE0 Bits 7-5 ILVDS2:ILVDS0 LVDS Output Current Bits 000 = 3.5mA LVDS Output Driver Current 001 = 4.0mA LVDS Output Driver Current 010 = 4.5mA LVDS Output Driver Current 011 = Not Used 100 = 3.0mA LVDS Output Driver Current 101 = 2.5mA LVDS Output Driver Current 110 = 2.
PAGE 28
LTC2172-12/ LTC2171-12/LTC2170-12 Applications Information GROUNDING AND BYPASSING The LTC2172-12/LTC2171-12/LTC2170-12 requires a printed circuit board with a clean unbroken ground plane. A multilayer board with an internal ground plane in the first layer beneath the ADC is recommended. Layout for the printed circuit board should ensure that digital and analog signal lines are separated as much as possible.
PAGE 29
LTC2172-12/ LTC2171-12/LTC2170-12 Typical Applications Silkscreen Top Top Side Inner Layer 2 GND Inner Layer 3 21721012fb 29
PAGE 30
LTC2172-12/ LTC2171-12/LTC2170-12 TYPICAL Applications Inner Layer 4 Inner Layer 5 Power Bottom Side Silkscreen Bottom 21721012fb 30
PAGE 31
LTC2172-12/ LTC2171-12/LTC2170-12 TYPICAL Applications LTC2172 Schematic SENSE C17 1µF PAR/SER C4 1µF R14 1k SDO VDD C5 1µF C3 0.1µF 10 11 AIN3 12 AIN3 13 C59 0.1µF 14 OUT1B– OUT1B+ OUT1A– OUT1A+ SDO GND PAR/SER GND VREF 37 AIN2– DCO+ REFH DCO– LTC2172 OVDD REFH 35 34 33 REFL OGND REFL FR+ 32 AIN3+ FR– 31 AIN3– OUT3A+ 30 VCM34 OUT3A– 29 AIN4+ OUT3B+ 28 AIN4– OUT3B– 27 VDD AIN4 AIN4 DIGITAL OUTPUTS 36 C16 0.
PAGE 32
LTC2172-12/ LTC2171-12/LTC2170-12 Package Description UKG Package 52-Lead Plastic QFN (7mm × 8mm) (Reference LTC DWG # 05-08-1729 Rev Ø) 7.50 ±0.05 6.10 ±0.05 5.50 REF (2 SIDES) 0.70 ±0.05 6.45 ±0.05 6.50 REF 7.10 ±0.05 8.50 ±0.05 (2 SIDES) 5.41 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 7.00 ± 0.10 (2 SIDES) 0.75 ± 0.05 0.00 – 0.05 R = 0.115 TYP 5.50 REF (2 SIDES) 51 52 0.40 ± 0.
PAGE 33
LTC2172-12/ LTC2171-12/LTC2170-12 Revision History REV DATE DESCRIPTION A 03/10 Changed Sampling Frequency Max for LTC2171-12 from 45MHz to 40MHz in the Timing Characteristics section. 6 Added full part numbers to Grounding and Bypassing and Heat Transfer sections in Applications Information. 28 Revised Descriptions and Comments in the Related Parts section 34 Revised Software Reset paragraph and Table 4 in the Applications Information section.
PAGE 34
LTC2172-12/ LTC2171-12/LTC2170-12 Related Parts PART NUMBER DESCRIPTION COMMENTS LTC2170-14/LTC217114/LTC2172-14 14-Bit, 25Msps/40Msps/65Msps 1.8V Quad ADCs, Ultralow Power 162mW/202mW/311mW, 73.7dB SNR, 90dB SFDR, Serial LVDS Outputs, 7mm × 8mm QFN-52 LTC2173-14/LTC217414/LTC2175-14 14-Bit, 80Msps/105Msps/125Msps 1.8V Quad ADCs, Ultralow Power 376mW/450mW/558mW, 73.4 dB SNR, 88dB SFDR, Serial LVDS Outputs, 7mm × 8mm QFN-52 LTC2173-12/LTC217412/LTC2175-12 12-Bit, 80Msps/105Msps/125Msps 1.