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TSA0801
8-BIT, 40MSPS, 40mW A/D CONVERTER
s 8-bit A/D converter in deep submicron CMOS s s s s s s s s
technology Single supply voltage: 2.5V Input range: 2Vpp differential 40Msps sampling frequency Ultra low power consumption: 40mW @ 40Msps (10mW @ 5Msps) ENOB=7.97 @ 40Msps, Fin=5MHz SFDR typically up to 68dB @ 40Msps, Fin=5MHz Built-in reference voltage with external bias capability Pinout compatibility with TSA1001, TSA1002 and TSA1201. ORDER CODE
Part Number TSA0801CF TSA0801CFT TSA0801IF TSA0801IFT EVAL0801/AA Temperature Range 0C to +70C 0C to +70C -40C to +85C -40C to +85C Package TQFP48 TQFP48 TQFP48 TQFP48 Conditioning Tray Tape & Reel Tray Tape & Reel Marking SA0801C SA0801C SA0801I SA0801I
Evaluation board
PIN CONNECTIONS (top view)
AGND AVCC VCCB GNDB AVCC VCCB DFSB OEB
NC
NC
NC
DR
index corner
DESCRIPTION
IPOL 1 2 3 4 5 6 7 8 9 10 11 12
48
47 46 45
44 43
42
41 40
39 38 37 36 NC 35 NC 34 NC 33 NC 32 NC 31 D0(LSB)
The TSA0801 is an 8-bit, 40MHz sampling frequency Analog to Digital converter using a deep submicron CMOS technology combining high performances and very low power consumption. The TSA0801 is based on a pipeline structure and digital error correction to provide excellent static linearity and go beyond 7.9 effective bits at Fs=40Msps, and Fin=5MHz. A voltage reference is integrated in the circuit to simplify the design and minimize external components. It is nevertheless possible to use the circuit with an external reference. Differential or single-ended analog inputs can be applied to the converter. A tri-state capability is available on the outputs. The output data can be coded into two different formats. A Data Ready signal is raised as the data is valid on the output and can be used for synchronization purposes. The TSA0801 is available in commercial (0 to +70C) and extended (-40 to +85C) temperature range, in a small 48 pins TQFP package. APPLICATIONS
VREFP VREFM AGND VIN AGND VINB AGND INCM AGND AVCC AVCC
TSA0801
30 D1 29 D2 28 D3 27 D4 26 D5 25 D6
13
14 15
16
17 18 19
20
21
22
23 24
DGND
D7 (MSB)
DVCC
DVCC
DGND
CLK
DGND
NC
GNDB
GNDB
VCCB
OR
PACKAGE
7 x 7 mm TQFP48
s s s s s
Hand-held instrumentation Medical imaging and Ultrasound Camcorders Computer scanners Digital communication
September 2002
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TSA0801
ABSOLUTE MAXIMUM RATINGS
Symbol AVCC DVCC VCCB IDout Tstg ESD Analog Supply voltage Digital Supply voltage
1)
Parameter
Values 0 to 3.3 0 to 3.3
Unit V V V mA C KV
1) 1)
Digital buffer Supply voltage Digital output current Storage temperature Electrical Static Discharge: - HBM - CDM-JEDEC Standard
0 to 3.3 -100 to 100 +150 2 1.5
1) All voltages values, except differential voltage, are with respect to network ground terminal. The magnitude of input and output voltages must never exceed -0.3V or VCC+0V
OPERATING CONDITIONS
Symbol AVCC DVCC VCCB VREFP Analog Supply voltage Digital Supply voltage Digital buffer Supply voltage Forced top reference voltage 1) Parameter Min 2.25 2.25 2.25 0.5 0 0.2 Typ 2.5 2.5 2.5 1 0 0.5 Max 2.7 2.7 2.7 1.8 0.5 1.1 Unit V V V V V V
VREFM Forced bottom reference voltage 1) INCM
1)
Forced input common mode voltage
Condition VRefP-VRefM>0.3V
BLOCK DIAGRAM
+2.5V
VREFP
GNDA VIN INCM VINB stage 1 stage 2 stage n Reference circuit IPOL VREFM
Sequencer-phase shifting CLK
DFSB OEB
Timing
Digital data correction DR DO TO D7 OR GND
Buffers
2/21
TSA0801
PIN CONNECTIONS (top view)
AGND AVCC VCCB
GNDB
AVCC
VCCB
DFSB
OEB
NC
NC
NC
DR
index corner
48 IPO L VREFP VRE FM AG ND V IN AG ND V INB AGN D INCM AG ND AVCC AVCC 1 2 3 4 5 6 7 8 9 10 11 12 13
47 46
45
44
43
42
41
40
39
38
37 36 NC 35 NC 34 NC 33 NC 32 NC 31 D0(LS B)
TSA0801
30 D1 29 D2 28 D3 27 D4 26 D5 25 D6
14 1 5
16
17
18
19
20
21
22
23
24
DGND
D7 (MSB)
DVCC
DVCC
DGND
CLK
DGND
NC
GNDB
GNDB
VCCB
OR
PIN DESCRIPTION
Pin No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Name IPOL VREFP VREFM AGND VIN AGND VINB AGND INCM AGND AVCC AVCC DVCC DVCC DGND CLK DGND NC DGND GNDB GNDB VCCB OR Description Analog bias current input Top voltage reference Bottom voltage reference Analog ground Analog input Analog ground Inverted analog input Analog ground Input common mode Analog ground Analog power supply Analog power supply Digital power supply Digital power supply Digital ground Clock input Digital ground Non connected Digital ground Digital buffer ground Digital buffer ground Digital buffer power supply Out Of Range output 0V 0V 0V 2.5V CMOS output (2.5V) CMOS output (2.5V) 1V 0V 0V 1Vpp 0V 1Vpp 0V 0.5V 0V 2.5V 2.5V 2.5V 2.5V 0V 2.5V compatible CMOS input 0V Observation Pin No 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 Name D6 D5 D4 D3 D2 D1 D0(LSB) NC NC NC NC NC NC DR VCCB GNDB VCCB NC NC OEB DFSB AVCC AVCC AGND Description Digital output Digital output Digital output Digital output Digital output Digital output Digital output Non connected Non connected Non connected Non connected Non connected Non connected Data Ready output Digital Buffer power supply Digital Buffer ground Digital Buffer power supply Non connected Non connected Output Enable input Data Format Select input Analog power supply Analog power supply Analog ground 2.5V compatible CMOS input 2.5V compatible CMOS input 2.5V 2.5V 0V CMOS output (2.5V) 2.5V 0V 2.5V Observation CMOS output (2.5V) CMOS output (2.5V) CMOS output (2.5V) CMOS output (2.5V) CMOS output (2.5V) CMOS output (2.5V) CMOS output (2.5V)
D7(MSB) Most Significant Bit output
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TSA0801
ELECTRICAL CHARACTERISTICS AVCC = DVCC = VCCB = 2.5V, Fs= 40Msps,Fin=1MHz, Vin@ -1.0dBFS, VREFM = 0V Tamb = 25C (unless otherwise specified) TIMING CHARACTERISTICS
Symbol FS DC TC1 TC2 Tod Tpd Ton Toff Parameter Sampling Frequency Clock Duty Cycle Clock pulse width (high) Clock pulse width (low) Data Output Delay (Fall of Clock 10pF load capacitance to Data Valid) Data Pipeline delay Falling edge of OEB to digital output valid data Rising edge of OEB to digital output tri-state Test conditions Min 0.5 30 11 11 50 12.5 12.5 5 5.5 1 1 Typ Max 40 70 Unit MHz % ns ns ns cycles ns ns
TIMING DIAGRAM
N+3
N+6
N+2 N-1 N N+1
N+7 N+8
CLK
Tpd + Tod OEB Tod Toff N-6 N-5 N-4 N-3 N-2 N-1 Ton N+1 N+2
DATA OUT
N-7
DR
HZ state
4/21
TSA0801
CONDITIONS AVCC = DVCC = VCCB = 2.5V, Fs= 40Msps,Fin= 1MHz, Vin@ -1.0dBFS, VREFM= 0V Tamb = 25C (unless otherwise specified) ANALOG INPUTS
Symbol Parameter Test conditions Min Typ 2.0 13 5.0 Vin@-1dBFS, FS=40Msps 1000 60 Max Unit Vpp
VIN-VINB Full scale reference voltage Req Cin BW ERB Equivalent input resistor Input capacitance Analog Input Bandwidth Effective Resolution Bandwidth1)
k
pF MHz MHz
1) See parameters definition for more information
REFERENCE VOLTAGE
Symbol VREFP Parameter Top internal reference voltage Test conditions Min 0.89 Tmin= -40C to Tmax= 85C1) 0.88 1.19 Vpol Ipol Ipol VINCM Analog bias voltage Analog bias current Analog bias current Input common mode voltage Tmin= -40C to Tmax= 85C1) Normal operating mode Shutdown mode 0.46 Tmin= -40C to Tmax= 85C1) 0.46 1.18 50 70 0 0.57 0.66 0.66 1.27 Typ 1.03 Max 1.16 1.16 1.35 1.36 100 Unit V V V V A A V V
1) Not fully tested over the temperature range. Guaranteed by sampling.
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TSA0801
CONDITIONS AVCC = DVCC = VCCB = 2.5V, Fs= 40Msps, Fin= 1MHz, Vin@ -1.0dBFS, VREFP=1V, VREFM= 0V Tamb = 25C (unless otherwise specified) POWER CONSUMPTION
Symbol ICCA Parameter
1)
Test conditions
Min
Typ 12.6
Max 20 21
Unit mA mA mA mA mA mA A mW mW mW C/W C/W
Analog Supply current Tmin= -40C to Tmax= 85C2)
1)
1.3
2)
2 2
ICCD
Digital Supply Current
1)
Tmin= -40C to Tmax= 85C ICCB Digital Buffer Supply Current Digital Buffer Supply Current in High Impedance Mode Power consumption in normal operation mode Power consumption in High Impedance mode Junction-ambient thermal resistor (TQFP48) Junction-case thermal resistor (TQFP48)
2.1
5 5
Tmin= -40C to Tmax= 85C2)
1)
ICCBZ
50 40 85C2) 35 80 18
110 60 62 55
1)
Pd
Tmin= -40C to Tmax=
1)
PdZ Rthja Rthjc
1) Rpol= 18K. Equivalent load: Rload= 470 and Cload= 6pF 2) Not fully tested over the temperature range. Guaranteed by sampling.
DIGITAL INPUTS AND OUTPUTS
Symbol Digital inputs VIL VIH Logic "0" voltage Logic "1" voltage 2.0 0.8 V V Parameter Test conditions Min Typ Max Unit
Digital Outputs VOL VOH IOZ CL Logic "0" voltage Logic "1" voltage Iol=10A Ioh=10A 2.4 -1.5 1.5 15 0.4 V V A pF
High Impedance leakage current OEB set to VIH Output Load Capacitance
ACCURACY
Symbol OE DNL INL 6/21 Parameter Offset Error Differential Non Linearity Integral Non Linearity Monotonicity and no missing codes Test conditions Min -40 -0.5 -1 Typ 5 Max 40 +0.5 +1 Guaranteed Unit mV LSB LSB
TSA0801
CONDITIONS AVCC = DVCC = 2.5V, Fs= 40Msps, Vin@ -1.0dBFS, VREFP=1V, VREFM= 0V Tamb = 25C (unless otherwise specified) DYNAMIC CHARACTERISTICS
Symbol Parameter Test conditions Fin= 5MHz Fin= 10MHz Fin= 24MHz SFDR Spurious Free Dynamic Range Fin= 5MHz Fin= 10MHz Fin= 24MHz Fin= 5MHz Fin= 10MHz Fin= 24MHz SNR Signal to Noise Ratio Fin= 5MHz Fin= 10MHz Fin= 24MHz Fin= 5MHz Fin= 10MHz Fin= 24MHz THD Total Harmonic Distortion Fin= 5MHz Fin= 10MHz Fin= 24MHz Fin= 5MHz Fin= 10MHz Fin= 24MHz Fin= 5MHz Fin= 10MHz Fin= 24MHz Fin= 5MHz Fin= 10MHz Fin= 24MHz ENOB Effective Number of Bits Fin= 5MHz Fin= 10MHz Fin= 24MHz
2) 1) 2) 1) 2) 1) 2) 1) 2) 1)
Min
Typ -68 -68 -67.7
Max -60 -60 -60 -60 -60 -59.8
Unit
dBc
dBc
48 48 48 48 48 48
48.8 48.8 48.8 dB
dB
-72.5 -72.5 -67
-56 -56 -56 -57 -55 -57 dB dB
48 48 48 48 48 48 7.8 7.8 7.8 7.8 7.8 7.8
48.7 48.7 48.7 dB
SINAD
Signal to Noise and Distortion Ratio
dB
7.97 7.97 7.96 bits
bits
1) Rpol= 18K. Equivalent load: Rload= 470 and Cload= 6pF 2) Tmin= -40C to Tmax= 85C. Not fully tested over the temperature range. Guaranteed by sampling.
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TSA0801
DEFINITIONS OF SPECIFIED PARAMETERS STATIC PARAMETERS Static measurements are performed through method of histograms on a 2MHz input signal, sampled at 40Msps, which is high enough to fully characterize the test frequency response. The input level is +1dBFS to saturate the signal. Differential Non Linearity (DNL) The average deviation of any output code width from the ideal code width of 1LSB. Integral Non linearity (INL) An ideal converter presents a transfer function as being the straight line from the starting code to the ending code. The INL is the deviation for each transition from this ideal curve. DYNAMIC PARAMETERS Dynamic measurements are performed by spectral analysis, applied to an input sine wave of various frequencies and sampled at 40Msps. Spurious Free Dynamic Range (SFDR) The ratio between the amplitude of fundamental tone (signal power) and the power of the worst spurious signal (not always an harmonic) over the full Nyquist band. It is expressed in dBc. Total Harmonic Distortion (THD) The ratio of the rms sum of the first five harmonic distortion components to the rms value of the fundamental line. It is expressed in dB. Signal to Noise Ratio (SNR) The ratio of the rms value of the fundamental component to the rms sum of all other spectral components in the Nyquist band (fs/2) excluding DC, fundamental and the first five harmonics. SNR is reported in dB. Signal to Noise and Distortion Ratio (SINAD) Similar ratio as for SNR but including the harmonic distortion components in the noise figure (not DC signal). It is expressed in dB. From the SINAD, the Effective Number of Bits (ENOB) can easily be deduced using the formula: SINAD= 6.02 x ENOB + 1.76 dB. When the applied signal is not Full Scale (FS), but has an A0 amplitude, the SINAD expression becomes: SINAD= 6.02 x ENOB + 1.76 dB + 20 log (2A0/FS) The ENOB is expressed in bits. Analog Input Bandwidth The maximum analog input frequency at which the spectral response of a full power signal is reduced by 3dB. Higher values can be achieved with smaller input levels. Effective Resolution Bandwidth (ERB) The band of input signal frequencies that the ADC is intended to convert without loosing linearity i.e. the maximum analog input frequency at which the SINAD is decreased by 3dB or the ENOB by 1/2 bit. Pipeline delay Delay between the initial sample of the analog input and the availability of the corresponding digital data output, on the output bus. Also called data latency. It is expressed as a number of clock cycles.
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TSA0801
Static parameter: Integral Non Linearity Fs=40MSPS; Fin=1MHz; Icca=11mA; N=65536pts
0 .1
0 .0 5
INL (LSBs)
0
-0 .0 5
-0 .1
-0 .1 5 0 50 100 O u tp u t C o d e 150 200 250
Static parameter: Differential Non Linearity Fs=40MSPS; Fin=1MHz; Icca=11mA; N=65536pts
0 .0 8 0 .0 6 0 .0 4 0 .0 2 DNL (LSBs) 0 -0 .0 2 -0 .0 4 -0 .0 6 -0 .0 8 -0 .1 0 50 100 O u tp u t C o d e 150 200 250
Linearity vs. Fs Fin=5MHz; Rpol adjustment
60 8 ENOB 55 50 45 40 35 30 20 30 40 50 60 SNR SINAD 6.5 6 5.5 5 7.5 7
Distortion vs. Fs Fin=5MHz; Rpol adjustment
-30
Dynamic parameters (dB)
Dynamic parameters (dB)
-40 -50 -60 -70 -80 -90 -100 20 30 40 50 60 SFDR THD
Fs (MHz)
ENOB (bits)
Fs (MHz)
9/21
TSA0801
Linearity vs. Fs Fin=15MHz; Rpol adjustment
56 8 ENOB 7.9 7.8 SNR SINAD
Distortion vs. Fs Fin=15MHz; Rpol adjustment
-40
Dynamic parameters (dB)
54 52 50 48 46 44 42 40 20 30 40
Dynamic parameters (dB)
-50 -60 -70 SFDR -80 -90 -100 20 30 40 50 60 THD
7.6 7.5 7.4 7.3 7.2 7.1 7 50 60
ENOB (bits)
7.7
Fs (MHz)
Fs (MHz)
Linearity vs. Fin Fs=40MSPS; Icca=11mA
55 8
Distortion vs. Fin Fs=40MSPS; Icca=11mA
-40
Dynamic parameters (dB)
Dynamic parameters (dB)
54 53 52 51 50 49 48 47 46 45 0 20 40 60 SINAD SNR ENOB
7.95 7.9
-45 -50 -55 -60 -65 -70 -75 -80 -85 -90 0 20 40 60 THD SFDR
7.8 7.75 7.7 7.65 7.6 7.55 7.5
ENOB (bits)
7.85
Fin (MHz)
Fin (MHz)
Linearity vs. Temperature Fs=40MSPS; Icca=11mA; Fin=5MHz
55
Distortion vs. Temperature Fs=40MSPS; Icca=11mA; Fin=5MHz;
8 7.95 7.9 7.85 7.8 7.75 7.7 7.65 7.6 7.55 7.5
90
Dynamic Parameters (dB)
54 53 52 51 50 49 48 47 46 45 -40 10
Dynamic Parameters (dB)
ENOB
85 80 75 70 65 SFDR 60 55 50 -40 10 60 THD
SNR SINAD
60
Temperature (C)
Temperature (C)
10/21
TSA0801
Power spectrum Fs=40MSPS - Icca=11mA - Fin=1MHz
0
Power spectrum (dBm) Power spectrum (dBm) Power spectrum (dBm)
-20
-40
-60
-80
-100
Power spectrum Fs=40MSPS - Icca=11mA - Fin=10MHz
0
-20
-40
-60
-80
100
Power spectrum Fs=40MHz - Icca=11mA - Fin=50MSPS
0
-20
-40
-60
-80
-100 0 2 4 6 8 10 12 14 16 18
Frequency (MHz)
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TSA0801
Linearity vs. AVcc Fs=40MSPS; Icca=11mA; Fin=1MHz
50 8 7.99 SNR SINAD 7.98 7.97 7.96 ENOB 7.95 7.94 7.93 7.92 7.91 7.9 2.35 2.45 2.55 2.65
Distortion vs. AVcc Fs=40MSPS; Icca=11mA; Fin=1MHz
Dynamic parameters (dB)
49.5 49 48.5 48 47.5 47 46.5 46 2.25
Dynamic Parameters (dB)
-61 -63 -65 -67 -69 SFDR -71 -73 -75 2.25 THD
ENOB (bits)
2.35
2.45
2.55
2.65
AVCC (V)
AVCC (V)
Linearity vs. DVcc Fs=40MSPS; Icca=11mA; Fin=1MHz
55 54 Dynamic parameters 53 52 51 50 49 48 47 46 45 2.25 2.35 2.45 2.55 2.65 SINAD SNR EN0B 8 7.95 7.9
Distortion vs. DVcc Fs=40MSPS; Icca=11mA; Fin=1MHz
-50
Dynamic parameters (dB)
-55 -60 -65 -70 SFDR -75 -80 2.25
7.8 7.75 7.7 7.65 7.6 7.55 7.5
ENOB (bits)
7.85
THD
2.35
2.45
2.55
2.65
DVCC (V)
DVCC (V)
Linearity vs. VccB Fs=40MSPS; Icca=11mA; Fin=1MHz
53 8
Distortion vs. VccB Fs=40MSPS; Icca=11mA; Fin=1MHz
-50
Dynamic parameters (dB)
52
Dynamic parameters (dB)
-55 -60 -65 -70 -75 -80 2.25 SFDR
50 49
SNR SINAD
7.9
48 47 46 2.25
ENOB (bits)
51
ENOB
7.95
7.85
THD
7.8 2.35 2.45 2.55 2.65
2.35
2.45
2.55
2.65
VCCB (V)
VCCB (V)
12/21
TSA0801 APPLICATION NOTE
DETAILED INFORMATION The TSA0801 is a High Speed analog to digital converter based on a pipeline architecture and the latest deep submicron CMOS process to achieve the best performances in terms of linearity and power consumption. The pipeline structure consists of 9 internal conversion stages in which the analog signal is fed and sequentially converted into digital data. Each 8 first stages consists of an Analog to Digital converter, a Digital to Analog converter, a Sample and Hold and a gain of 2 amplifier. A 1.5bit conversion resolution is achieved in each stage. The latest stage simply is a comparator. Each resulting LSB-MSB couple is then time shifted to recover from the conversion delay. Digital data correction completes the processing by recovering from the redundancy of the (LSB-MSB) couple for each OPERATIONAL MODES DESCRIPTION Inputs Analog input differential level (VIN-VINB) > RANGE -RANGE > (VIN-VINB) RANGE> (VIN-VINB) >-RANGE (VIN-VINB) > RANGE -RANGE > (VIN-VINB) RANGE> (VIN-VINB) >-RANGE X Data Format Select (DFSB) When set to low level (VIL), the digital input DFSB provides a two's complement digital output MSB. This can be of interest when performing some further signal processing. When set to high level (VIH), DFSB provides a standard binary output coding. Output Enable (OEB) When set to low level (VIL), all digital outputs remain active and are in low impedance state. DFSB H H H L L L X OEB L L L L L L H OR H H L H H L HZ DR CLK CLK CLK CLK CLK CLK HZ Outputs Most Significant Bit (MSB) D9 D9 D9 Complemented D9 Complemented D9 Complemented D9 HZ stage. The corrected data are outputted through the digital buffers. Signal input is sampled on the rising edge of the clock while digital outputs are delivered on the falling edge of the Data Ready signal. The advantages of such a converter reside in the combination of pipeline architecture and the most advanced technologies. The highest dynamic performances are achieved while consumption remains at the lowest level. Some functionalities have been added in order to simplify as much as possible the application board. These operational modes are described in the following table. The TSA0801 is pin to pin compatible with the 10bits/25Msps TSA1001, the 10bits/50Msps TSA1002 and the 12bits/50Msps TSA1201. This ensures a conformity within the product family and above all, an easy upgrade of the application.
When set to high level (VIH), all digital outputs buffers are in high impedance state. This results in lower consumption while the converter goes on sampling. When OEB is set to low level again, the data is then valid on the output with a very short Ton delay. The timing diagram summarizes this operating cycle.
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TSA0801
Out of Range (OR) This function is implemented on the output stage in order to set up an "Out of Range" flag whenever the digital data is over the full scale range. Typically, there is a detection of all the data being at'0' or all the data being at'1'. This ends up with an output signal OR which is in low level state (VOL) when the data stay within the range, or in high level state (VOH) when the data are out of the range. Data Ready (DR) The Data Ready output is an image of the clock being synchronized on the output data (D0 to D9). This is a very helpful signal that simplifies the synchronization of the measurement equipment or the controlling DSP. As digital output, DR goes in high impedance state when OEB is asserted to High level as described in the timing diagram. REFERENCES AND COMMON MODE CONNECTION VREFM must be always connected externally. Internal reference and common mode In the default configuration, the ADC operates with its own reference and common mode voltages generated by its internal bandgap. VREFM pin is connected externally to the Analog Ground while VREFP (respectively INCM) is set to its internal voltage of 1.03V (respectively 0.57V). It is recommended to decouple the VREFP in order to minimize low and high frequency noise (refer to Figure 1) Figure 1 : Internal reference and common mode setting
1.03V VIN VREFP 0.57V
330pF 10nF 4.7uF 330pF 10nF 4.7uF
application needs (Refer to table 'OPERATING CONDITIONS' page 2 for min/max values). The VREFP, VREFM voltages set the analog dynamic at the input of the converter that has a full scale amplitude of 2*(VREFP-VREFM). In case of analog dynamic lower than 2Vpp, the best linearity and distortion performance is achieved while increasing the VREFM voltage instead of lowering the VREFP one. The INCM is the mid voltage of the analog input signal. It is possible to use an external reference voltage device for specific applications requiring even better linearity, accuracy or enhanced temperature behavior. Using the STMicroelectronics TS821 or TS4041-1.2 Vref leads to optimum performances when configured as shown on Figure 2. Figure 2 : External reference setting
1k
330pF 10nF 4.7uF
VCCA VREFP VIN
TSA0801
VINB VREFM
TS821 TS4041 external reference
TSA0801
VINB INCM VREFM
At 15Msps sampling frequency, 1MHz input frequency and -1dBFS amplitude signal, performances can be improved up to 2dBc on SFDR and 0.3dB on SINAD. At 40Msps sampling frequency, 1MHz input frequency and -1dBFS amplitude signal, performances can be improved up to 1dBc on SFDR and 0.6dB on SINAD. This can be very helpful for example for multichannel application to keep a good matching among the sampling frequency range.
External reference and common mode Each of the voltages VREFM, VREFP and INCM can be fixed externally to better fit to the
14/21
TSA0801
DRIVING THE ANALOG INPUT Differential inputs The TSA0801 has been designed to obtain optimum performances when being differentially driven. An RF transformer is a good way to achieve such performances. Figure 3 describes the schematics. The input signal is fed to the primary of the transformer, while the secondary drives both ADC inputs. Figure 3 : Differential input configuration with transformer
Analog source ADT1-1 1:1 VIN
50 100pF
Figure 4 represents the biasing of a differential input signal in AC-coupled differential input configuration. Both inputs VIN and VINB are centered around the common mode voltage, that can be let internal or fixed externally. Figure 5 shows a DC-coupled configuration with forced INCM to the DC analog input (mid-voltage) while VREFM is connected to ground and VFREFP let internal (to 1V); we achieve a 2Vpp differential amplitude. Figure 5 : DC-coupled 2Vpp differential analog input
analog DC analog AC+DC VIN
VREFP
TSA0801
VINB INCM
TSA0801
VINB
VREFM
INCM DC
330pF 10nF
4.7uF
330pF
10nF
4.7uF
VREFP-VREFM = 1 V
The common mode voltage of the ADC (INCM) is connected to the center-tap of the secondary of the transformer in order to bias the input signal around this common voltage, internally set to 0.57V. The INCM is decoupled to maintain a low noise level on this node. Our evaluation board is mounted with a 1:1 ADT1-1WT transformer from Minicircuits. You might also use a higher impedance ratio (1:2 or 1:4) to reduce the driving requirement on the analog signal source. For example, with internal references, each analog input can drive a 1Vpp amplitude input signal, so the resultant differential amplitude is 2Vpp. Figure 4 : AC-coupled differential input
Single-ended input configuration The single-ended input configuration of the TSA0801 requires particular biasing and driving. The structure being fully differential, care has to be taken in order to properly bias the inputs in single-ended mode. Figure 6 summarizes the link from the differential configuration to the single-ended one; a wrong configuration is also presented. - With differential driving, both inputs are centered around the INCM voltage. - The transition to single-ended configuration implies to connect the unused input (VINB for instance) to the DC component of the single input (VIN) and also to the input common mode in order to be well balanced. The mid-code is achieved at the crossing between VIN and VINB, therefore inputs are conveniently biased. - Unlikely other structures of converters in which the unused channel can be grounded; in our case it will end with unbalanced inputs and saturation of the internal amplifiers leading to a non respect of the output codes.
15/21
50 common mode
10nF 100k 33pF 100k 10nF
VIN INCM
TSA0801
VINB
50
TSA0801
Figure 6 : Input dynamic range for the various configurations
Differential configuration +FS: code 1023 VIN - VINB +FS: code 1023 VIN - VINB VINB VIN INCM VIN 0: code 511 0: code 511 INCM VIN Single-ended configuration: balanced inputs Single-ended configuration: unbalanced inputs +FS + offset: code > 1023 VIN - VINB
INCM
-FS: code 0 -FS: code 0 Ao + ac VIN VINB Ao + ac VIN VINB Ao
-FS + offset: code > 0
Ao + ac
VIN VINB
Ao + ac
INCM Ao
INCM
INCM
Ao Wrong configuration!
The applications requiring single-ended inputs can be configured like reported on Figure 7 for an AC-coupled input or on Figure 8 and 9 for a DC-coupled input. In the case of AC-coupled analog input, the analog inputs VIN and VINB are biased to the same voltage that is the common mode voltage of the circuit (INCM). The INCM and reference voltages may remain at their internal level but can also be fixed externally.
Figure 8 : DC-coupled 2Vpp analog input
Analog DC AC+DC VIN
VREFP
TSA0801
VINB
VREFM
INCM
330pF
10nF
4.7uF
VREFP-VREFM = 1 V
Figure 7 : AC-coupled Single-ended input Figure 9 describes a configuration for a 1Vpp analog signal with a 0.5V DC input. In this case, while VREFP is kept internally at 1V, VREFM is connected to VINB and INCM externally to 0.5V; the dynamic is then 1Vpp (VREFP-VREFM=0.5V).
TSA0801
Signal source
10nF 50 common mode 33pF 100k
VIN INCM
100k
Figure 9 : DC-coupled 1Vpp analog input
Analog DC AC+DC VIN
VINB
TSA0801
VINB VREFM INCM
In the case of DC-coupled analog input with 1V DC signal, the DC component of the analog input set the common mode voltage. As an example figure 8, INCM is set to the 1V DC analog input while VREFM is connected to ground and VREFP is let internal (1V); we achieve a 2Vpp differential amplitude.
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0.5V power supply
330pF
10nF
4.7uF
VREFP-VREFM = 0.5 V
TSA0801
Dynamic characteristics, while not being as remarkable as for differential configuration, are still of very good quality. Power consumption optimization The internal architecture of the TSA0801 enables to optimize the power consumption according to the sampling frequency of the application. For this purpose, a resistor is placed between IPOL and the analog Ground pins. The TSA0801 will combine highest performances and lowest consumption at 40Msps when Rpol is equal to 18k. At lower sampling frequency range (< 10Msps), this value of resistor may be adjusted in order to decrease the analog current without any degradation of dynamic performances. As an example, 10mW total power consumption is achieved at 5Msps with a Rpol value of 390k. The table below sums up the relevant data. Total power consumption optimization depending on Rpol value
Fs (Msps) Rpol (k) Optimized power (mW) 5 390 10 15 40 25 25 25 35 40 18 40
Linearity, distortion performance towards Clock Duty Cycle variation The TSA0801 has an outstanding behaviour towards clock duty cycle variation and it may be also reinforced with adjustment of analog current consumption. Linearity vs. Duty cycle Fs=40MSPS; Icca=11mA; Fin=1MHz
80 8 ENOB 7.5 7 6.5 6 5.5 5 30 40 50 60 70
Distortion vs. Duty cycle Fs=40MSPS; Icca=11mA; Fin=1MHz
0
Dynamic parameters (dB)
75 70 65 60 55 50 45 40 35 30
Dynamic parameters (dB)
-10 -20 -30 -40 -50 -60 -70 -80 -90 -100 30 40 50 60 70 SFDR THD
SNR SINAD
Duty Cycle (%)
ENOB (bits)
Duty Cycle (%)
Linearity vs. Duty cycle Fs=40MSPS; consumption optimized; Fin=1MHz
70 Dynamic parameters (dB), analog current cons. (mA) 60 50 SINAD 40 6.5 30 20 10 0 30 40 50 60 70 6 Icca (mA) 5.5 5 ENOB 8
Distortion vs. Duty cycle Fs=40MSPS; consumption optimized; Fin=1MHz
-20 -30 Dynamic parameters (dB), analog current cons. (mA) -40 -50 -60 -70 -80 -90 -100 -110 -120 30 40 50 60 70
ICCA THD SFDR
100 90 80 70 60 50 40 30 20 10 0 analog current cons. (mA)
7.5 SNR 7
ENOB (bits)
Duty Cycle (%)
Duty Cycle (%)
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TSA0801
Clock input The converter quality is very dependant on clock input accuracy, in terms of aperture jitter; the use of low jitter crystal controlled oscillator is recommended. The clock power supplies must be separated from the ADC output ones to avoid digital noise modulation at the output. It is recommended to keep the circuit clocked, to avoid random states, before applying the supply voltages. Layout precautions To use the ADC circuits in the best manner at high frequencies, some precautions have to be taken for power supplies: - First of all, the implementation of 4 separate proper supplies and ground planes (analog, digital, internal and external buffer ones) on the PCB is recommended for high speed circuit applications to provide low inductance and low resistance common return. The separation of the analog signal from the digital part is essential to prevent noise from coupling onto the input signal. - Power supply bypass capacitors must be placed as close as possible to the IC pins in order to improve high frequency bypassing and reduce harmonic distortion. - Proper termination of all inputs and outputs must be incorporated with output termination resistors; then the amplifier load will be only resistive and the stability of the amplifier will be improved. All leads must be wide and as short as possible especially for the analog input in order to decrease parasitic capacitance and inductance. - To keep the capacitive loading as low as possible at digital outputs, short lead lengths of routing are essential to minimize currents when the output changes. To minimize this output capacitance, buffers or latches close to the output pins will relax this constraint. - Choose component sizes as small as possible (SMD). EVAL0801 evaluation board The characterization of the board has been made with a fully ADC devoted test bench as shown on Figure 10. The analog signal must be filtered to be very pure. The dataready signal is the acquisition clock of the logic analyzer. The ADC digital outputs are latched by the octal buffers 74LCX573. All characterization measurements have been made with: SFSR=+0.2dB for static parameters.SFSR=-0.5dB for dynamic parameters.
Figure 10 : Analog to Digital Converter characterization bench
HP8644 Sine Wave Generator Vin ADC evaluation board
Data Logic Analyzer Clk Clk HP8133 Pulse Generator PC
HP8644
Sine Wave Generator
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J9 DFSB J11 1 2 1 2 1 2 VCCB2 C34
+
J10 OEB J13 1 2
J17 VDDBUFF3V
R10 47K R11 47K R12 47K R13 47K C16 AVCC 470nF C15 470nF C27 470nF C39 C28 VCCB1 47 C37
J2 Raj1 47K 10nF C14 R2 1K 330pF 330pF R14 R15 R16 R17 R18 R19 47K 47K 47K 47K 47K 47K 330pF 10nF C25 10nF C26 DR DO D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 74LCX573 C41 10F C29 6 2 4
+
1 2
VrefP
1 2
J6
J5
1 2
VrefM C32 470nF AGND AVCC AVCC DFSB OEB NC NC 2.5VCCBUFF GNDBUFF 2.5VCCBUFF DR D0 C1 100pF 10nF C30 330pF 470nF 10nF 330pF C31 C13 C12 C11 48 47 46 45 44 43 42 41 40 39 38 37
J1 Vin
1
T2
6
Figure 11: TSA0801 evaluation board schematic
R1 50 3
2
4 T2-AT1-1WT C9 8-14bits ADC TSA0801 74LCX573 330pF C5 C3 330pF AVCC 470nF 10nF 330pF C4 C2 C8
1 2 3 4 5 6 7 8 9 10 OEB VCC D0 Q0 D1 Q1 D2 Q2 D3 Q3 D4 U2 Q4 D5 Q5 D6 Q6 D7 Q7 GND LE
20 19 18 17 16 15 14 13 12 11
J7
C10
1 2 C6
470nF 10nF
Regl com mode J8
C7
1 2 13 14 15 16 17 18 19 20 21 22 23 24
Mes com Mode J12
DVCC DVCC DGND CLK DGND NC DGND GNDBUFF GNDBUFF 2.5VCCBUFF OR D13
470nF 10nF
1 2 3 4 5 6 7 8 9 10 11 12 Ipol VrefP VrefM AGND Vin AGND VINB AGND INCM AGND AVCC AVCC 1 2 3 4 5 6 7 8 9 10 OEB VCC D0 Q0 D1 U3 Q1 D2 Q2 D3 Q3 D4 Q4 D5 Q5 D6 Q6 D7 Q7 GND LE 20 19 18 17 16 15 14 13 12 11 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12
36 35 34 33 32 31 30 29 28 27 26 25
2 1
AVCC
+
C42 47F
D13 C38 OR
J19 C20 10F C17
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 470nF C40 32PIN
1 2
AGND
J20 1 330pF C21 3 R3 50 10nF C19 470nF C24 10
+
1 2 10nF C22 470nF C23 10
+
T1 T2-AT1-1WT 330pF C18
10nF C33 330pF
DGND
J21
1 2
GndB2 C36 47 2 1 J4 CLJ/SMB C35 47 VCCB1
J22
1 2 2 1
J15 DVCC
J16 CON2
J18 VccB1
2 1
GndB1
TSA0801
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TSA0801
Figure 12: circuit board - Top side silkscreen
Printed circuit board - List of components
P art T ype 10 uF 10 uF 10 uF 10 uF 10 0pF 10 nF 10 nF 10 nF 10 nF 10 nF 10 nF 10 nF 10 nF 10 nF 10 nF 10 nF 1K 3 2P IN 3 30pF 3 30pF D es i gn F o o t pr int at o r C 24 C 23 C 41 C 29 C1 C 12 C 39 C 15 C 40 C 27 C4 C 21 C 31 C6 C9 C 18 R2 J6 C 25 C 26 1210 1210 1210 1210 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 ID C 32 6 03 6 03 P ar t T ype 330 pF 330 pF 330 pF 330 pF 330 pF 330 pF 330 pF 330 pF 330 pF 47uF 47uF 47uF 47uF 470 nF 470 nF 470 nF 470 nF 470 nF 470 nF 470 nF D es ign F o o t pr int at o r C 33 C 20 C8 C2 C5 C 11 C 30 C 17 C 14 C 36 C 34 C 35 C 42 C 22 C 32 C 37 C 38 C 13 C 28 C 10 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 CA P CA P CA P CA P 8 05 8 05 8 05 8 05 8 05 8 05 8 05 P ar t T ype 47 0nF 47 0nF 47 0nF 47 0nF 47 K 47 K 47 K 47 K 47 K 47 K 47 K 47 K 47 K 47 K 47 K 50 50 D es i gn F o o t pr int at o r C7 C 16 C 19 C3 R 12 R 14 R 11 R aj1 R 10 R 19 R 13 R 15 R 16 R 17 R 18 R3 R1 8 05 8 05 8 05 8 05 6 03 6 03 6 03 VR 5 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 6 03 T S S OP 2 0 T S S OP 2 0 S IP 2 P ar t T ype A VC C C L J /S M B A GN D DF SB D GN D D VC C GndB 1 GndB 2 D es ign at o r J 12 J4 J 19 J9 J20 J 15 J22 J21 F IC H E 2M M S M B /H F IC H E 2M M F IC H E 2M M F IC H E 2M M F IC H E 2M M F IC H E 2M M F IC H E 2M M F IC H E 2M M F IC H E 2M M F IC H E 2M M ADT ADT F IC H E 2M M F IC H E 2M M S M B /H F IC H E 2M M F IC H E 2M M T QF P 48 F o o t pr int
M es co m mo de J 8 OE B J 10
R egl co m mo de J 7 T 2-A T 1-1W T T 2-A T 1-1W T VccB 1 VD D B U F F 3V Vin Vr ef M Vr ef P T S A 08 01 T2 T1 J 18 J 17 J1 J5 J2 U1
74 L C X5 73 U 3 74 L C X5 73 U 2 C ON 2 J 16
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TSA0801
PACKAGE MECHANICAL DATA: 48 PINS - PLASTIC PACKAGE
A A2 48 1 e A1 37 36 0,10 mm .004 inch SEATING PLANE
12 13 24
25
E3 E1 E
D3 D1 D
L1
L
K
Millimeters Dim. Min. A A1 A2 B C D D1 D3 e E E1 E3 L L1 K 0.05 1.35 0.17 0.09 Typ. Max. 1.60 0.15 1.45 0.27 0.20
0,25 mm .010 inch GAGE PLANE
Min. 0.002 0.053 0.007 0.004
B
c
Inches Typ. Max. 0.063 0.006 0.057 0.011 0.008 1.40 0.22 9.00 7.00 5.50 0.50 9.00 7.00 5.50 0.60 1.00 0.055 0.009 0.354 0.276 0.216 0.0197 0.354 0.276 0.216 0.024 0.039 0.45 0.75 0.018
0.030
0 (min.), 7 (max.)
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics. (c) The ST logo is a registered trademark of STMicroelectronics (c) 2002 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - Canada - China - Finland - France - Germany - Hong Kong - India - Israel - Italy - Japan - Malaysia Malta - Morocco - Singapore - Spain - Sweden - Switzerland - United Kingdom - United States (c) http://www.st.com
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