VCA2612Y/250

VCA2612_14 TI1 | Alldatasheet

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Technical content

Dual, VARIABLE GAIN AMPLIFIER with Low Noise Preamp FEA TURES G LOW NOISE PREAMP:

• Low Input Noise: 1.25nV/√Hz
• Active Termination Noise Reduction
• Switchable Termination Value
• 80MHz Bandwidth
• 5dB to 25dB Gain Range
• Differential Input/Output G LOW NOISE VARIABLE GAIN AMPLIFIER:
• Low Noise VCA: 3.3nV/ √Hz, Differential Programming Optimizes Noise Figure
• 24dB to 45dB Gain
• 40MHz Bandwidth
• Differential Input/Output G LOW CROSSTALK: 52dB at Max Gain, 5MHz G HIGH-SPEED VARIABLE GAIN ADJUST G SWITCHABLE EXTERNAL PROCESSING APPLICA TIONS G ULTRASOUND SYSTEMS G WIRELESS RECEIVERS G TEST EQUIPMENT VCA2612VCA2612

DESCRIPTION

The VCA2612 is a highly integrated, dual receive channel, signal processing subsystem. Each channel of the product consists of a low noise preamplifier (LNP) and a Variable Gain Amplifier (VGA). The LNP circuit provides the neces- sary connections to implement Active Termination (AT), a method of cable termination which results in up to 4.6dB noise figure improvement. Different cable termination char- acteristics can be accommodated by utilizing the VCA2612’s switchable LNA feedback pins. The LNP has the ability to accept both differential and single-ended inputs, and gener- ates a differential output signal. The LNP provides strappable gains of 5dB, 17dB, 22dB, and 25dB. The output of the LNP can be accessed externally for further signal processing, or fed directly into the VGA. The VCA2612’s VGA section consists of two parts: the Voltage Controlled Attenuator (VCA) and the Programmable Gain Amplifier (PGA). The gain and gain range of the PGA can be digitally programmed. The combination of these two programmable elements results in a variable gain ranging from 0dB up to a maximum gain as defined by the user through external connections. The output of the VGA can be used in either a single-ended or differential mode to drive high-performance Analog-to-Digital (A/D) converters. The VCA2612 also features low crosstalk and outstanding distortion performance. The combination of low noise and gain range programmability make the VCA2612 a versatile building block in a number of applications where noise performance is critical. The VCA2612 is available in a TQFP-48 package. Low Noise Preamp 5dB to 25dB Programmable Gain Amplifier 24 to 45dB Voltage Controlled Attenuator Analog Control Maximum Gain Select RF 2 RF 1 FB SWFB LNP INPC C C F LNP INN LNP GS1 LNP GS2 LNP GS3 LNP Gain Set Input LNP OUT P SELVCA INP LNP OUT NV C A INNV C A CNTLFBSW CNTL VCA OUT P VCA OUT N MGS 1 MGS 2 MGS 3 Maximum Gain Select VCA2612 (1 of 2 Channels) www.ti.com Copyright © 2000-2004, Texas Instruments Incorporated Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. SBOS117C – SEPTEMBER 2000 – REVISED APRIL 2004 PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. All trademarks are the property of their respective owners.

SBOS117Cwww.ti.com

ELECTRICAL CHARACTERISTICS

At TA = +25°C, VDDA = VDDB = VDDR = +5V, load resistance = 500Ω on each output to ground, MGS = 011, LNP = 22dB and fIN = 5MHz, unless otherwise noted. The input to the preamp (LNP) is single-ended, and the output from the VCA is single-ended unless otherwise noted. ABSOLUTE MAXIMUM RATINGS (1) NOTE: (1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. PACKAGE PACKAGE ORDERING TRANSPORT PRODUCT PACKAGE-LEAD DESIGNATOR MARKING NUMBER MEDIA, QUANTITY VCA2612Y TQFP-48 PFB VCA2612Y VCA2612Y/250 Tape and Reel, 250 """ " VCA2612Y/2K Tape and Reel, 2000 PACKAGE/ORDERING INFORMATION (1) NOTE: (1) For the most current package and ordering information, see the Package Option Addendum located at the end of this data sheet. ELECTROSTATIC DISCHARGE SENSITIVITY This integrated circuit can be damaged by ESD. Texas Instru- ments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. VCA2612Y PARAMETER CONDITIONS MIN TYP MAX UNITS PREAMPLIFIER Input Resistance 600 k Ω Input Capacitance 15 pF Input Bias Current 1n A CMRR f = 1MHz, VCA CNTL = 0.2V 50 dB Maximum Input Voltage Preamp Gain = +5dB 1 V PP Preamp Gain = +25dB 112 mV PP Input Voltage Noise(1) Preamp Gain = +5dB 3.5 nV/ √Hz Preamp Gain = +25dB 1.25 nV/ √Hz Input Current Noise Independent of Gain 0.35 pA/ √Hz Noise Figure, RS = 75Ω , RIN = 75Ω (1) R F = 550Ω , Preamp Gain = 22dB, 6.2 dB PGA Gain = 39dB Bandwidth Gain = 22dB 80 MHz PROGRAMMABLE VARIABLE GAIN AMPLIFIER Peak Input Voltage Differential 2 V PP –3dB Bandwidth 40 MHz Slew Rate 300 V/ µs Output Signal Range R L ≥ 500Ω Each Side to Ground 2 V PP Output Impedance f = 5MHz 1 Ω Output Short-Circuit Current ±40 mA Third Harmonic Distortion f = 5MHz, V OUT = 1VPP , VCACNTL = 3.0V –45 –71 dBc Second Harmonic Distortion f = 5MHz, V OUT = 1VPP , VCACNTL = 3.0V –45 –63 dBc IMD, Two-Tone V OUT = 2VPP , f = 1MHz –80 dBc VOUT = 2VPP , f = 10MHz –80 dBc 1dB Compression Point f = 5MHz, Output Referred, Differential 6 V PP Crosstalk VOUT = 1VPP , f = 1MHz, Max Gain Both Channels 68 dB Group Delay Variation 1MHz < f < 10MHz, Full Gain Range ±2n s DC Output Level, VIN = 0 2.5 V ACCURACY Gain Slope 10.9 dB/V Gain Error ±1(2) dB Output Offset Voltage ±50 mV Total Gain VCA CNTL = 0.2V 18 21 24 dB VCA CNTL = 3.0V 47 50 53 dB GAIN CONTROL INTERFACE Input Voltage (VCACNTL ) Range 0.2 to 3.0 V Input Resistance 1M Ω Response Time 45dB Gain Change, MGS = 111 0.2 µs POWER SUPPLY Operating Temperature Range –40 +85 °C Specified Operating Range 4.75 5.0 5.25 V Power Dissipation Operating, Both Channels 410 495 mW Thermal Resistance, θJA TQFP-48 56.5 °C/W NOTE: (1) For preamp driving VGA. (2) Referenced to best fit dB-linear curve.

SBOS117C www.ti.com PIN CONFIGURATION 1V DD A Channel A +Supply (+5V)

2 NC Do Not Connect

3 NC Do Not Connect

4 VCA

INNA Channel A VCA Negative Input

5 VCA INPA Channel A VCA Positive Input

6L N P OUT NA Channel A LNP Negative Output 7L N P OUT PA Channel A LNP Positive Output

8 SWFBA Channel A Switched Feedback Output

9 FBA Channel A Feedback Output

10 COMP1A Channel A Frequency Compensation 1

11 COMP2A Channel A Frequency Compensation 2

12 LNP

INNA Channel A LNP Inverting Input

13 LNP GS3 A Channel A LNP Gain Strap 3

14 LNP GS2 A Channel A LNP Gain Strap 2

15 LNP GS1 A Channel A LNP Gain Strap 1

16 LNP INPA Channel A LNP Noninverting Input

17 V DD R +Supply for Internal Reference (+5V)

18 V BIAS 0.01µF Bypass to Ground 19 V CM 0.01µF Bypass to Ground

20 GNDR Ground for Internal Reference

21 LNP

INPB Channel B LNP Noninverting Input

22 LNP GS1 B Channel B LNP Gain Strap 1

23 LNP GS2 B Channel B LNP Gain Strap 2

24 LNP GS3 B Channel B LNP Gain Strap 3

25 LNP INNB Channel B LNP Inverting Input

26 COMP2B Channel B Frequency Compensation 2

27 COMP1B Channel B Frequency Compensation 1

28 FBB Channel B Feedback Output

29 SWFBB Channel B Switched Feedback Output

30 LNP

OUT PB Channel B LNP Positive Output

31 LNP OUT NB Channel B LNP Negative Output

32 VCA INPB Channel B VCA Positive Input

33 VCA INNB Channel B VCA Negative Input

34 NC Do Not Connect

35 NC Do Not Connect

DD B Channel B +Analog Supply (+5V)

37 GNDB Channel B Analog Ground

38 VCA

OUT NB Channel B VCA Negative Output

39 VCA OUT PB Channel B VCA Positive Output

40 MGS 3 Maximum Gain Select 3 (LSB)

41 MGS 2 Maximum Gain Select 2

42 MGS 1 Maximum Gain Select 1 (MSB)

43 VCA CNTL VCA Control Voltage

44 VCA INSEL VCA Input Select, HI = External

45 FBSW CNTL Feedback Switch Control: HI = ON

46 VCA OUT PA Channel A VCA Positive Output

47 VCA OUT NA Channel A VCA Negative Output

48 GNDA Channel A Analog Ground

PIN DESIGNATOR DESCRIPTION PIN DESIGNATOR DESCRIPTION PIN DESCRIPTIONS VDD B NC NC VCA INNB VCA INPB LNP OUT NB LNP OUT PB SWFBB FBB COMP1B COMP2B LNP INNB GNDA VCA OUT NA VCA OUT PA FBSW CNTL VCA INSEL VCA CNTL MGS 1 MGS 2 MGS 3 VCA OUT PB VCA OUT NB GNDB LNP GS3 A LNP GS2 A LNP GS1 A LNP INPA VDD R VBIAS VCM GNDR LNP INPB LNP GS1 B LNP GS2 B LNP GS3 B VDD A NC NC VCA INNA VCA INPA LNP OUT NA LNP OUT PA SWFBA FBA COMP1A COMP2A LNP INNA 48 47 46 45 44 43 42 41 40 39 38 13 14 15 16 17 18 19 20 21 22 23 VCA2612

SBOS117Cwww.ti.com TYPICAL CHARACTERISTICS At TA = +25°C, VDDA = VDDB = VDDR = +5V, load resistance = 500Ω on each output to ground, MGS = 011, LNP = 22dB and fIN = 5MHz, unless otherwise noted. The input to the preamp (LNP) is single-ended, and the output from the VCA is single-ended unless otherwise noted. This results in a 6dB reduction in signal amplitude compared to differential operation. GAIN vs VCACNTL VCA CNTL (V) Gain (dB) MGS = 111 MGS = 110 MGS = 101 MGS = 100 MGS = 011 MGS = 010 MGS = 001 MGS = 000 GAIN ERROR vs TEMPERATURE VCA CNTL (V) Gain Error (dB) 2.0 1.5 1.0 0.5 –0.5 –1.0 –1.5 –2.0 +25°C –40°C +85°C GAIN ERROR vs VCA CNTL VCA CNTL (V) Gain Error (dB) 2.0 1.5 1.0 0.5 –0.5 –1.0 –1.5 –2.0 10MHz 1MHz 5MHz GAIN ERROR vs VCA CNTL VCA CNTL (V) Gain Error (dB) 2.0 1.5 1.0 0.5 –0.5 –1.0 –1.5 –2.0 MGS = 011MGS = 000 MGS = 111 GAIN MATCH: CHA to CHB, VCACNTL = 0.2V Delta Gain (dB) Units 100 GAIN MATCH: CHA to CHB, VCACNTL = 3.0V Delta Gain (dB) Units 100

SBOS117C www.ti.com TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VDDA = VDDB = VDDR = +5V, load resistance = 500Ω on each output to ground, MGS = 011, LNP = 22dB and fIN = 5MHz, unless otherwise noted. The input to the preamp (LNP) is single-ended, and the output from the VCA is single-ended unless otherwise noted. This results in a 6dB reduction in signal amplitude compared to differential operation. GAIN vs FREQUENCY (Pre-Amp) Frequency (MHz) 0.1 1 10 100 Gain (dB) LNP = 25dB LNP = 22dB LNP = 17dB LNP = 5dB GAIN vs FREQUENCY (VCA and PGA, VCACNTL = 0.2V) Frequency (MHz) 0.1 1 10 100 Gain (dB) 5.0 4.0 3.0 2.0 1.0 0.0 –1.0 –2.0 –3.0 –4.0 –5.0 MGS = 111 MGS = 100 MGS = 011 MGS = 000 GAIN vs FREQUENCY (VCA and PGA, VCACNTL = 3.0V) Frequency (MHz) 0.1 1 10 100 Gain (dB) MGS = 111 MGS = 100 MGS = 011 MGS = 000 GAIN vs FREQUENCY (VCA CNTL = 3.0V) Frequency (MHz) 0.1 1 10 100 Gain (dB) LNP = 25dB LNP = 22dB LNP = 5dB LNP = 17dB GAIN vs FREQUENCY (LNP = 22dB) Frequency (MHz) 0.1 1 10 100 Gain (dB) VCA CNTL = 3.0V VCA CNTL = 1.6V VCA CNTL = 0.2V OUTPUT REFERRED NOISE vs VCA CNTL VCA CNTL (V) Noise (nV/√Hz) 1800 1600 1400 1200 1000 800 600 400 200 R S= 50Ω MGS = 111 MGS = 011

SBOS117Cwww.ti.com TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VDDA = VDDB = VDDR = +5V, load resistance = 500Ω on each output to ground, MGS = 011, LNP = 22dB and fIN = 5MHz, unless otherwise noted. The input to the preamp (LNP) is single-ended, and the output from the VCA is single-ended unless otherwise noted. This results in a 6dB reduction in signal amplitude compared to differential operation. INPUT REFERRED NOISE vs R S R S (Ω ) 1 10 100 1000 Noise (nV√Hz 10.0 1.0 0.1 NOISE FIGURE vs RS (VCA CNTL = 3.0V) R S (Ω ) 10 100 1000 Noise Figure (dB) NOISE FIGURE vs VCA CNTL VCA CNTL (V) Noise Figure (dB) INPUT REFERRED NOISE vs VCA CNTL VCA CNTL (V) Noise (nV/√Hz) MGS = 011 MGS = 111 R S= 50Ω LNP vs FREQUENCY (Differential, 2VPP ) Frequency (MHz) 0.1 1 10 100 Harmonic Distortion (dBc) –45 –50 –55 –60 –65 –70 –75 –80 3rd Harmonic 2nd Harmonic LNP vs FREQUENCY (Single-Ended, 1VPP ) Frequency (MHz) 0.1 1 10 100 Harmonic Distortion (dBc) –45 –50 –55 –60 –65 –70 –75 –80 2nd Harmonic 3rd Harmonic

SBOS117C www.ti.com TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VDDA = VDDB = VDDR = +5V, load resistance = 500Ω on each output to ground, MGS = 011, LNP = 22dB and fIN = 5MHz, unless otherwise noted. The input to the preamp (LNP) is single-ended, and the output from the VCA is single-ended unless otherwise noted. This results in a 6dB reduction in signal amplitude compared to differential operation. HARMONIC DISTORTION vs FREQUENCY (Differential, 2VPP , MGS = 000) Frequency (MHz) 0.1 1 10 Harmonic Distortion (dBc) –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 VCA CNTL = 0.2V, H2 VCA CNTL = 0.2V, H3 VCA CNTL = 3.0V, H2 VCA CNTL = 3.0V, H3 HARMONIC DISTORTION vs FREQUENCY (Differential, 2VPP , MGS = 011) Frequency (Hz) 0.1 1 10 Harmonic Distortion (dBc) –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 VCA CNTL = 0.2V, H2 VCA CNTL = 0.2V, H3 VCA CNTL = 3.0V, H2 VCA CNTL = 3.0V, H3 HARMONIC DISTORTION vs FREQUENCY (Differential, 2VPP , MGS = 111) Frequency (MHz) 0.1 1 10 Harmonic Distortion (dBc) –30 –35 –40 –45 –50 –55 –60 –65 –70 –75 –80 VCA CNTL = 0.2V, H2 VCA CNTL = 0.2V, H3 VCA CNTL = 3.0V, H2 VCA CNTL = 3.0V, H3 HARMONIC DISTORTION vs FREQUENCY (Single-Ended, 1VPP , MGS = 000) Frequency (MHz) 0.1 1 10 Harmonic Distortion (dBc) –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 VCA CNTL = 0.2V, H2 VCA CNTL = 0.2V, H3 VCA CNTL = 3.0V, H2 VCA CNTL = 3.0V, H3 HARMONIC DISTORTION vs FREQUENCY (Single-Ended, 1VPP , MGS = 011) Frequency (MHz) 0.1 1 10 Harmonic Distortion (dBc) –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 –90 VCA CNTL = 0.2V, H2 VCA CNTL = 0.2V, H3 VCA CNTL = 3.0V, H2 VCA CNTL = 3.0V, H3 HARMONIC DISTORTION vs FREQUENCY (Single-Ended, 1VPP , MGS = 111) Frequency (MHz) 0.1 1 10 Harmonic Distortion (dBc) –30 –35 –40 –45 –50 –55 –60 –65 –70 –75 –80 –85 VCA CNTL = 0.2V, H2 VCA CNTL = 0.2V, H3 VCA CNTL = 3.0V, H2 VCA CNTL = 3.0V, H3

SBOS117Cwww.ti.com TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VDDA = VDDB = VDDR = +5V, load resistance = 500Ω on each output to ground, MGS = 011, LNP = 22dB and fIN = 5MHz, unless otherwise noted. The input to the preamp (LNP) is single-ended, and the output from the VCA is single-ended unless otherwise noted. This results in a 6dB reduction in signal amplitude compared to differential operation. –1dB COMPRESSION vs VCA CNTL VCA CNTL (V) PIN (dBm) –10 –15 –20 –25 –30 –35 –40 3rd-ORDER INTERCEPT vs VCA CNTL VCA CNTL (V) IP3 (dBm) –10 –15 –20 –25 –30 –35 –40 –45 –50 HARMONIC DISTORTION vs VCA CNTL (Differential, 2VPP ) VCA CNTL (V) Harmonic Distortion (dBc) –45 –50 –55 –60 –65 –70 –75 –80 MGS = 000, H2 MGS = 011, H2 MGS = 111, H2 MGS = 000, H3 MGS = 011, H3 MGS = 111, H3 HARMONIC DISTORTION vs VCA CNTL (Single-Ended, 1VPP ) VCA CNTL (V) Harmonic Distortion (dBc) –45 –50 –55 –60 –65 –70 –75 –80 MGS = 000, H2 MGS = 011, H2 MGS = 111, H2 MGS = 000, H3 MGS = 011, H3 MGS = 111, H3 INTERMODULATION DISTORTION (Differential, 2VPP , f = 10MHz) Frequency (MHz) 9.989.96 10 10.2 10.4 Power (dBFS) –15 –25 –35 –45 –55 –65 –75 –85 –95 –105 INTERMODULATION DISTORTION (Single-Ended, 1VPP , f = 10MHz) Frequency (MHz) 9.989.96 10 10.2 10.4 Power (dBFS) –15 –25 –35 –45 –55 –65 –75 –85 –95 –105

SBOS117C www.ti.com TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VDDA = VDDB = VDDR = +5V, load resistance = 500Ω on each output to ground, MGS = 011, LNP = 22dB and fIN = 5MHz, unless otherwise noted. The input to the preamp (LNP) is single-ended, and the output from the VCA is single-ended unless otherwise noted. This results in a 6dB reduction in signal amplitude compared to differential operation. CMRR vs FREQUENCY (LNP only) Frequency (MHz) 0.1 1 10 100 CMRR (dB) –10 –20 –30 –40 –50 –60 –70 –80 PULSE RESPONSE (BURSTS) (Differential, VCACNTL = 3.0V, MGS = 111) 200ns/div Output 500mV/div Input 1mV/div OVERLOAD RECOVERY (Differential, VCACNTL = 3.0V, MGS = 111) Input 1mV/div Output 1V/div 200ns/div GAIN RESPONSE (Differential, VCACNTL Pulsed, MGS = 111) Output 500mV/div Input 2V/div 100ns/div CMRR vs FREQUENCY (VCA only) Frequency (MHz) 0.1 1 10 100 CMRR (dB) –10 –20 –30 –40 –50 –60 –70 –80 –90 VCA CNTL = 0.2V VCA CNTL = 1.4V VCA CNTL = 3.0V CROSS TALK vs FREQUENCY (Single-Ended, 1Vp-p, MGS = 011) Frequency (MHz) 1 10 100 Cross Talk (dB) –10 –20 –30 –40 –50 –60 –70 –80 –90 VCA CNTRL = 0V VCA CNTRL = 1.5V VCA CNTRL = 3.0V

SBOS117Cwww.ti.com TYPICAL CHARACTERISTICS (Cont.) At TA = +25°C, VDDA = VDDB = VDDR = +5V, load resistance = 500Ω on each output to ground, MGS = 011, LNP = 22dB and fIN = 5MHz, unless otherwise noted. The input to the preamp (LNP) is single-ended, and the output from the VCA is single-ended unless otherwise noted. This results in a 6dB reduction in signal amplitude compared to differential operation. 79.5 78.5 77.5 76.5 ICC vs TEMPERATURE Temperature (°C) –40 –10 5–25 35 50 20 65 80 95 ICC (mA) GROUP DELAY vs FREQUENCY Frequency (MHz) 1 10 100 Group Delay (ns) VCA CNTL = 3.0V VCA CNTL = 0.2V –45 –40 –35 –30 –25 –20 –15 –10 PSRR vs FREQUENCY Frequency (Hz) 10 1k 100 100k 1M 10k 10M PSRR (dB)

each circuit block are provided in the following sections. large bias currents required in both input and output stages. same role for signals on the –IN side. FIGURE 4. Schematic of the Low Noise Preamplifier (LNP). 59µs at the lowest gain (25dB).

SBOS117C www.ti.com LNP GAIN (dB) Input-Referred Output-Referred 25 1.54 2260 22 1.59 1650 17 1.82 1060 5 4.07 597 The LNP is capable of generating a 2VPP differential signal. The maximum signal at the LNP input is therefore 2VPP divided by the LNP gain. An input signal greater than this would exceed the linear range of the LNP, an especially important consideration at low LNP gain settings. ACTIVE FEEDBACK WITH THE LNP One of the key features of the LNP architecture is the ability to employ active-feedback termination to achieve superior noise performance. Active feedback termination achieves a lower noise figure than conventional shunt termination, es- sentially because no signal current is wasted in the termina- tion resistor itself. Another way to understand this is as follows: Consider first that the input source, at the far end of the signal cable has a cable-matching source resistance of R S. Using conventional shunt termination at the LNP input, a second terminating resistor of value RS is connected to ground. Therefore, the signal loss is 6dB due to the voltage divider action of the series and shunt R S resistors. The effective source resistance has been reduced by the same factor of 2, but the noise contribution has been reduced by only the √2, only a 3dB reduction. Therefore, the net theoreti- cal SNR degradation is 3dB, assuming a noise-free amplifier input. (In practice, the amplifier noise contribution will de- grade both the unterminated and the terminated noise fig- ures, somewhat reducing the distinction between them.) See Figure 5 for an amplifier using active feedback. This diagram appears very similar to a traditional inverting ampli- fier. However, the analysis is somewhat different because the gain A in this case is not a very large open-loop op amp gain; rather, it is the relatively low and controlled gain of the LNP itself. Thus, the impedance at the inverting amplifier terminal will be reduced by a finite amount, as given in the familiar relationship of Equation (3): R R AIN F= +( )1 where RF is the feedback resistor (supplied externally be- tween the LNPINP and FB terminals for each channel), A is the user-selected gain of the LNP, and RIN is the resulting amplifier input impedance with active feedback. In this case, unlike the conventional termination above, both the signal voltage and the R S noise are attenuated by the same factor It is also possible to create other gain settings by connecting an external resistor between LNPGS1 on one side, and LNPG S2 and/or LNPGS3 on the other. In that case, the internal resistor values shown in Figure 4 should be com- bined with the external resistor to calculate the effective value of R S for use in Equation (1). The resulting expression for external resistor value is given in Equation (2). R RR R R G a i nRR Gain R REXT S L FIX L S FIX S L = +• where REXT is the externally selected resistor value needed to achieve the desired gain setting, RS1 is the fixed parallel resistor in Figure 4, and RFIX is the effective fixed value of the remaining internal resistors: RS2, RS3, or (RS2 || RS3) depend- ing on the pin connections. Note that the best process and temperature stability will be achieved by using the pre-programmed fixed gain options of Table I, since the gain is then set entirely by internal resistor ratios, which are typically accurate to ±0.5%, and track quite well over process and temperature. When combining exter- nal resistors with the internal values to create an effective R S value, note that the internal resistors have a typical tempera- ture coefficient of +700ppm/°C and an absolute value toler- ance of approximately ±5%, yielding somewhat less predict- able and stable gain settings. With or without external resis- tors, the board layout should use short Gain Strap connec- tions to minimize parasitic resistance and inductance effects. The overall noise performance of the VCA2612 will vary as a function of gain. Table II shows the typical input- and output-referred noise densities of the entire VCA2612 for maximum VCA and PGA gain; i.e., VCA CNTL set to 3.0V and all MGS bits set to 1. Note that the input-referred noise values include the contribution of a 50Ω fixed source imped- ance, and are therefore somewhat larger than the intrinsic input noise. As the LNP gain is reduced, the noise contribu- tion from the VCA/PGA portion becomes more significant, resulting in higher input-referred noise. However, the output- referred noise, which is indicative of the overall SNR at that gain setting, is reduced. NOISE (nV/√ Hz) TABLE II. Noise Performance for MGS = 111 and VCACNTL = 3.0V. LNP PIN STRAPPING LNP GAIN (dB) LNPG S1, LNPGS2, LNPGS3 Connected Together 25 LNPG S1 Connected to LNPGS3 22 LNPG S1 Connected to LNPGS2 17 All Pins Open 5 TABLE I. Pin Strappings of the LNP for Various Gains. (3) (2) where RL is the load resistor in the drains of Q3 and Q8, and R S is the resistor connected between the sources of the input transistors Q4 and Q7. The connections for various RS com- binations are brought out to device pins LNPGS1, LNPGS2, and LNPG S3 (pins 13-15 for channel A, 22-24 for channel B). These Gain Strap pins allow the user to establish one of four fixed LNP gain options as shown in Table I. To preserve the low noise performance of the LNP, the user should take care to minimize resistance in the input lead. A parasitic resistance of only 10Ω will contribute 0.4nV/ √Hz .

www.ti.com 10-Jun-2014 Addendum-Page 1 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/Ball Finish (6) MSL Peak Temp (3) Op Temp (°C) Device Marking (4/5) Samples VCA2612Y/250 ACTIVE TQFP PFB 48 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR VCA2612Y (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

www.ti.com 10-Jun-2014 Addendum-Page 2

*All dimensions are nominal Device Package Type Package Drawing Pins SPQ Reel Diameter (mm) Reel Width W1 (mm) (mm) (mm) (mm) (mm) W (mm) Pin1 Quadrant PACKAGE MATERIALS INFORMATION www.ti.com 21-May-2014 Pack Materials-Page 1

*All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) VCA2612Y/250 TQFP PFB 48 250 336.6 336.6 31.8 PACKAGE MATERIALS INFORMATION www.ti.com 21-May-2014 Pack Materials-Page 2

MTQF019A – JANUARY 1995 – REVISED JANUARY 1998 POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 PFB (S-PQFP-G48) PLASTIC QUAD FLATPACK 4073176/B 10/96 Gage Plane 0,13 NOM 0,25 0,45 0,75 Seating Plane 0,05 MIN 0,17 0,27 SQ 7,20 6,80 5,50 TYP SQ8,80 9,20 1,05 0,95 1,20 MAX 0,08 0,50 M0,08 0°–7° NOTES: A. All linear dimensions are in millimeters. B. This drawing is subject to change without notice. C. Falls within JEDEC MS-026

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