LMH6518SQEVK National Semiconductor, LMH6518SQEVK Datasheet

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LMH6518SQEVK

Manufacturer Part Number
LMH6518SQEVK
Description
KIT EVAL FOR LMH6518 VGA
Manufacturer
National Semiconductor
Series
PowerWise®r
Datasheets

Specifications of LMH6518SQEVK

Channels Per Ic
1 - Single
Amplifier Type
Variable Gain
Output Type
Differential
-3db Bandwidth
900MHz
Operating Temperature
-40°C ~ 85°C
Current - Supply (main Ic)
210mA
Voltage - Supply, Single/dual (±)
4.75 V ~ 5.25 V
Board Type
Fully Populated
Utilized Ic / Part
LMH6518
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Current - Output / Channel
-
Slew Rate
-
Lead Free Status / Rohs Status
Supplier Unconfirmed
© 2008 National Semiconductor Corporation
LMH6518
900 MHz, Digitally Controlled, Variable Gain Amplifier
General Description
The LMH6518 is a digitally controlled variable gain amplifier
whose total gain can be varied from −1.16 dB to 38.8 dB for
a 40 dB range in 2 dB steps. The −3 dB bandwidth is 900 MHz
at all gains. Gain accuracy at each setting is typically 0.1 dB.
When used in conjunction with a National Semiconductor
Gsample/second (Gsps) ADC with adjustable full scale (FS)
range, the LMH6518 gain adjustment will accommodate full
scale input signals from 6.8 mV
mV
Aux” and “−OUT Aux”) follows the Main output and is intended
for use in Oscilloscope trigger function circuitry but may have
other uses in other applications.
The LMH6518 gain is programmed via a SPI-1 compatible
serial bus. A signal path combined gain resolution of 8.5 mdB
can be achieved when the LMH6518’s gain and the Gsps
ADC’s FS input are both manipulated. Inputs and outputs are
DC-coupled. The outputs are differential with individual Com-
mon Mode (CM) voltage control (for Main and Auxiliary out-
puts) and have a selectable bandwidth limiting circuitry
(common to both Main and Auxiliary) of 20, 100, 200, 350,
650, 750 MHz or full bandwidth.
Functional Block Diagram
TRI-STATE
PP
nominal at the ADC input. The Auxiliary output (“+OUT
®
is a registered trademark of National Semiconductor Corporation.
PP
to 920 mV
300688
PP
to get 700
Features
Applications
Gain range
Gain step size
Combined gain resolution with
Gsample/second ADC’s
Min gain
Max gain
−3 dB BW
Rise/fall time
Recovery time
Propagation delay variation
HD2 @ 100 MHz
HD3 @ 100 MHz
Input-referred noise (max gain)
Over-voltage clamps for fast recovery
Power consumption
Oscilloscope programmable gain amplifier
Differential ADC drivers
High frequency single-ended input to differential
conversion
Precision gain control applications
Medical applications
RF/IF applications
— Auxiliary turned off
30068801
October 6, 2008
www.national.com
0.98 nV/
−1.16 dB
900 MHz
8.5 mdB
−50 dBc
−53 dBc
<500 ps
38.8 dB
100 ps
0.75W
40 dB
<5 ns
1.1W
2 dB
Hz

Related parts for LMH6518SQEVK

LMH6518SQEVK Summary of contents

Page 1

... The −3 dB bandwidth is 900 MHz at all gains. Gain accuracy at each setting is typically 0.1 dB. When used in conjunction with a National Semiconductor Gsample/second (Gsps) ADC with adjustable full scale (FS) range, the LMH6518 gain adjustment will accommodate full scale input signals from 6 ...

Page 2

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. ESD Tolerance (Note 5) Human Body Model Machine Model Charge Device Model Supply Voltage V (5V nominal (3.3V nominal) DD Differential Input Input Common Mode Voltage ...

Page 3

Symbol Parameter IMD3 Intermodulation Distortion (Note 12) OIP3_1 Intermodulation Intercept (Note 12) P_1dB_main −1 dB Compression P_1dB_aux Gain Parameters A Max Gain V_DIFF_MAX A Min Gain V_DIFF_MIN Gain_Step Gain Step Size Gain Step Size with ADC (See Application Information section) ...

Page 4

Symbol Parameter V Voltage range at each output pin OUT_MAX1 (clamped) V OUT_MAX2 V OUT_MAX3 V OUT_MAX4 Z Differential Output Impedance OUT_DIFF V Output Offset Voltage OOS V Output Offset Voltage Shift OOS_shift1 V OOS_shift2 TCV Output Offset Voltage Drift ...

Page 5

Symbol Parameter Power Requirements I Supply Current S1 I S1_off I DD Bandwidth Limiting Filter Specifications Filter Parameter 20 MHz Pass Band Tolerance (All Gains) 100 MHz Pass Band Tolerance (All Gains) 200 MHz Pass Band Tolerance (All Gains) 350 ...

Page 6

V OOS 23. V O_CM 24. V OS_CM ΔV 25. O_CM 26. ΔV 27. OUT Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is ...

Page 7

Connection Diagram Ordering Information Package Part Number LMH6518SQ 16-Pin LLP LMH6518SQE LMH6518SQX 16-Pin 30068888 Top View Package Marking Transport Media 1k Units Tape and Reel L6518SQ 250 Units Tape and Reel 4.5k Units Tape and Reel 7 NSC Drawing SQA16A ...

Page 8

Typical Performance Characteristics = 1.2V, Single-ended input drive, V AUX V differential (both Main and Auxiliary Outputs), Main output specification (Auxiliary is labeled “Auxiliary”), full bandwidth setting, PP gain = 18.8 dB (Preamp LG ladder attenuation), Full Power ...

Page 9

Phase vs. Gain Auxiliary Response Over Temperature 30068855 Response vs. Gain 30068847 Response Over Temperature 30068852 Main vs. Auxiliary Response Phase vs. Gain 9 30068856 30068854 30068848 www.national.com ...

Page 10

Response vs. Gain Balance Error Noise vs. Ladder Attenuation www.national.com Phase vs. Gain 30068849 Linear Phase Deviation and Group Delay 30068853 Noise vs. Ladder Attenuation 30068807 10 30068850 30068840 30068837 ...

Page 11

Noise Figure vs. Gain 30068838 Input Current Noise vs. Frequency 30068879 HD3 vs. Ladder Attenuation 30068875 Input Voltage Noise vs. Frequency HD2 vs. Ladder Attenuation HD2 vs. Ladder Attenuation 11 30068878 30068874 30068872 www.national.com ...

Page 12

HD3 vs. Ladder Attenuation Main and Auxiliary Distortion Comparison Gain vs. Ladder Attenuation www.national.com Main and Auxiliary Distortion Comparison 30068873 Distortion vs. Output Power 30068897 Gain Accuracy vs. Ladder Attenuation 30068871 12 30068896 30068898 30068869 ...

Page 13

Auxiliary Gain Accuracy vs. Ladder Attenuation A V_CM A V_CM Gain Matching vs. Ladder Attenuation 30068870 30068858 −1 dB Compression vs. Ladder Attenuation 30068859 13 30068868 A V_CM 30068857 30068876 www.national.com ...

Page 14

Step Response Step Response Output Offset Voltage (Typical Unit 1) www.national.com Step Response 30068889 Step Response 30068891 Output Offset Voltage (Typical Unit 2) 30068865 14 30068890 30068892 30068866 ...

Page 15

Output Offset Voltage (Typical Unit 3) 30068867 Supply Current vs. Supply Voltage 30068863 Input Bias Current vs. Input CM 30068861 V vs. V OS_CM CM Supply Current vs. Supply Voltage Auxiliary Output Voltage (Hi-Z Mode) 15 30068860 30068864 30068862 www.national.com ...

Page 16

Filter BW vs. Gain Output vs. Input Output vs. Input www.national.com Output vs. Input 30068895 Output vs. Input 30068881 Overdrive Recovery Time (Return to Zero) 30068883 16 30068880 30068882 30068893 ...

Page 17

... Full Scale, FS, adjustment (through their Extended Control Mode or ECM) to provide near-continuous variability (8.5 mdB resolution) to cover a 42 input range. The National Semiconductor GSample/sec- ond ECM control allows the ADC set using the ADC SPI bus. The ADC FS voltage range is from 560 mV to 840 mV with 9 bits of FS voltage control ...

Page 18

FS signal from 6.8 mV LMH6518 input, with 0. 2.62-2) overlap. Assuming a nominal 0.7V output, the LMH6518’s minimum PP FS input swing is limited by the maximum signal path gain possible and vice versa: (or ...

Page 19

TABLE 1. Oscilloscope Example Including Front-End Attenuators “S”, Scope Vertical Row Scope FS Input (V ) Scale (V/DIV 8m-24m 1m-3m 2 24m-80m 3m-10m 3 80m-0.8 10m-0.1 4 0.8-8 0.1-1 5 8-80 1-10 In Table 1, the highest FS ...

Page 20

Required condition: 0 ECM (ratio) 6. Determine the ECM binary code to be sent on ADC SPI bus: Convert the ECM value represented by the ratio calculated above, to binary: ECM (binary) = DEC2BIN{ECM(ratio)* 511, 9} INPUT/OUTPUT CONSIDERATIONS The ...

Page 21

FIGURE 5. Output CM Shift Scheme With the scheme of Figure kept at 1.2V, by proper selection of external resistor values, so that the LMH6518 outputs are not CM-loaded. As was the case with input level shifting, ...

Page 22

From Figure 6, the signal path consists of the input impedance switch, the attenuator switch, Low Noise Amplifier (LNA, JFET amplifier) to drive the LMH6518 input (+IN), and the DAC to provide offset adjust. The LNA must have the follow- ...

Page 23

FIGURE 8. Serial Interface Protocol- Read Operation FIGURE 9. Serial Interface Protocol- Write Operation FIGURE 10. Read Timing FIGURE 11. Write Timing 23 30068884 30068885 30068886 30068887 www.national.com ...

Page 24

D15 D14 D13 D12 D11 (MSB Note: Bits D5, D9, D11-D14 must be “0”. Otherwise, device operation is undefined and specifications are not guaranteed. D15 D14 D13 D12 D11 (MSB ...

Page 25

OSCILLOSCOPE TRIGGER APPLICATIONS With the Auxiliary output of the LMH6518 offering a second output that follows the Main one (except for a slightly reduced distortion performance), the oscilloscope trigger function can be implemented by tapping this output. The “V the ...

Page 26

Trigger. The result could be a loss of Trigger pulse and/or visual distortion of the displayed waveform. To avoid this sce- nario, the oscilloscope should detect an excessive overdrive and go into trigger-loss mode. Done this way, the oscilloscope display ...

Page 27

Table 8 lists other possible JFET candidates that fall in the range of speed (f ) and low noise needed: t TABLE 8. Suitable JFET Candidates Specifications Company Part Number V (V) P Interfet IF140 −2.2 Interfet IF142 −2.2 Interfet ...

Page 28

Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 16-Pin Package NS Package Number SQA16A 28 ...

Page 29

Notes 29 www.national.com ...

Page 30

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock Conditioners www.national.com/timing Data Converters www.national.com/adc Displays www.national.com/displays Ethernet www.national.com/ethernet Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www ...

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