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VCA2618
VCA 261 8
SBOS254A - JULY 2002 - REVISED NOVEMBER 2002
Dual, VARIABLE GAIN AMPLIFIER with Input Buffer
FEATURES
q q q q q q GAIN RANGE: 27dB to 45dB 30MHz BANDWIDTH LOW CROSSTALK: 65dB at Max Gain, 5MHz HIGH-SPEED VARIABLE GAIN ADJUST POWER SHUTDOWN MODE HIGH IMPEDANCE INPUT BUFFER
DESCRIPTION
The VCA2618 is a highly integrated, dual receive channel, Variable Gain Amplifier (VGA) with analog gain control. The VCA2618'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 single-ended unity gain input buffer provides predictable high input impedance. 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. A separate power-down pin reduces power consumption. The VCA2618 also features low crosstalk and outstanding distortion performance. The combination of low noise and gain range programmability make the VCA2618 a versatile building block in a number of applications where noise performance is critical. The VCA2618 is available in a TQFP-32 package.
CP2A CP1A
APPLICATIONS
q q q q ULTRASOUND SYSTEMS WIRELESS RECEIVERS TEST EQUIPMENT RADAR
VCA2618 (1 of 2 Channels) NOUTA Voltage Control Attenuator Programmable Gain Amplifier
INA
Buffer
POUTA
MGS1 VCACNTL Analog Control Maximum Gain Select MGS2 MGS3
Maximum Gain Select
NOUTB Voltage Control Attenuator Programmable Gain Amplifier
INB
Buffer
POUTB
CP2B
CP1B
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.
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.
Copyright (c) 2002, Texas Instruments Incorporated
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ABSOLUTE MAXIMUM RATINGS(1)
Power Supply (+VS) ............................................................................. +6V Analog Input ............................................................. -0.3V to (+VS + 0.3V) Logic Input ............................................................... -0.3V to (+VS + 0.3V) Case Temperature ......................................................................... +100C Junction Temperature .................................................................... +150C Storage Temperature ...................................................... -40C to +150C NOTE: (1) Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. Exposure to absolute maximum conditions for extended periods may affect device reliability.
ELECTROSTATIC DISCHARGE SENSITIVITY
This integrated circuit can be damaged by ESD. Texas Instruments 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.
PACKAGE/ORDERING INFORMATION
PACKAGE DESIGNATOR(1) PBS SPECIFIED TEMPERATURE RANGE -40C to +85C PACKAGE MARKING VCA2618Y ORDERING NUMBER VCA2618YT VCA2618YR TRANSPORT MEDIA, QUANTITY Tape and Reel, 250 Tape and Reel, 2000
PRODUCT VCA2618Y
PACKAGE-LEAD TQFP-32 Surface-Mount
"
"
"
"
"
NOTE: (1) For the most current specifications and package information, refer to our web site at www.ti.com.
ELECTRICAL CHARACTERISTICS
At TA = +25C, VDD = 5V, load resistance = 500 on each output to ground differential output (2Vp-p), MGS = 111, and fIN = 5MHz, unless otherwise noted. VCA2618Y PARAMETER BUFFER Input Resistance Input Capacitance Input Bias Current Maximum Input Voltage Input Voltage Noise Input Current Noise Noise Figure Bandwidth CONDITIONS MIN TYP MAX UNITS
PGA Gain = 45dB, RS = 50 Independent of Gain RF = 550, PGA Gain = 45dB, RS = 75
600 5 1 1 5.4 350 13 100 1 30 300 2.5 1 1 40 -50 -50 -60 -40 to -45 5 -59 65 13 16 2(1) 50 0.2 to 3.0 1 0.2 4.75 5.0 120 9.2 5.25 150
k pF nA Vp-p nV/Hz fA/Hz dB MHz Vp-p MHz V/s V mA dBc dBc dBc dB ns dBc dB ns dB/V dB mV V M s V mW mW
PROGRAMMABLE VARIABLE GAIN AMPLIFIER Peak Input Voltage -3dB Bandwidth Slew Rate Output Signal Range RL 500 Each Side to Ground Output Impedance Output Short-Circuit Current 3rd-Harmonic Distortion VOUT = 2Vp-p, VCACNTL = 3.0V 2nd-Harmonic Distortion VOUT = 2Vp-p, VCACNTL = 3.0V 2nd-Harmonic Distortion VOUT = 2Vp-p, VCACNTL = 3.0V, MGS = 011 Overload Performance (2nd-Harmonic Input Signal = 1Vp-p, VCACNTL = 2V Distortion) Time Delay IMD, 2-Tone VOUT = 2Vp-p, f = 9.95MHz Crosstalk Group Delay Variation 1MHz < f < 10MHz, Full Gain Range ACCURACY Gain Slope Gain Error Output Offset Voltage GAIN CONTROL INTERFACE Input Voltage (VCACNTL) Range Input Resistance Response Time POWER SUPPLY Specified Operating Range Power Dissipation Power-Down NOTE: (1) Referenced to best fit dB-linear curve. VCACNTL = 0.2V to 3.0V
-45 -42
45dB Gain Change
Operating, Each Channel
2
VCA2618
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SBOS254A
PIN CONFIGURATION
Top View NOUTA GNDA POUTA TQFP
32
31
30
29
28
VDDA
DNC
CP2A
CP1A
NC
27
26
+INA NC VDDR VBIAS VCM GNDR NC +INB
1 2 3 4 VCA2618 5 6 7 8
25
24 23 22 21 20 19 18 17
VCACNTL MGS3 MGS2 MGS1 PD NC NC DNC
10
11
12
13
14
15 POUTB
PIN DESCRIPTIONS
PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 DESIGNATOR +INA NC VDDR VBIAS VCM GNDR NC +INB NC DNC CP2B CP1B VDDB GNDB POUTB NOUTB DESCRIPTION Noninverting Input Channel A No Internal Connection Internal Reference Supply Bias Voltage Common-Mode Voltage Internal Reference Ground Not Connected Noninverting Input Channel B No Internal Connection Do Not Connect Coupling Capacitor Channel B Coupling Capacitor Channel B +5V Supply Channel B Ground Channel B Positive Output Channel B Negative Output Channel B PIN 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 DESIGNATOR DNC NC NC PD MGS1 MGS2 MGS3 VCACNTL NOUTA POUTA GNDA VDDA CP1A CP2A DNC NC DESCRIPTION Do Not Connect No Internal Connection No Internal Connection Power-Down (Active LOW) Maximum Gain Select 1 (MSB) Maximum Gain Select 2 Maximum Gain Select 3 (LSB) VCA Analog Control Negative VCA Output Channel A Positive VCA Output Channel A Ground Channel A +5V Supply Channel A Coupling Capacitor Channel A Coupling Capacitor Channel A Do Not Connect No Internal Connection
VCA2618
SBOS254A
NOUTB
VDDB
CP2B
DNC
CP1B
NC
GNDB
16
9
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TYPICAL CHARACTERISTICS
At TA = +25C, VDD = 5V, load resistance = 500 on each output to ground, differential output (2Vp-p) MGS = 111, and fIN = 5MHz, unless otherwise noted.
GAIN vs VCA 50 45 40 35 30 25 20 15 10 5 0 -5 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 VCACNTL (V) MGS = 001 MGS = 010 MGS = 011 MGS = 111 MGS = 110 MGS = 101 MGS = 100 2.0
GAIN ERROR vs TEMPERATURE +85C 1.5 +25C 1.0
Gain Error (dB)
Gain (dB)
0.5 0 -0.5 -40C -1.0 -1.5 -2.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 VCACNTL (V)
GAIN ERROR vs VCACNTL 2.5 2.0 1.5 10MHz 2.5 2.0 1.5
GAIN ERROR vs VCACNTL MGS = 001 MGS = 011
Gain Error (dB)
0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 VCACNTL (V) 5MHz 1MHz
Gain Error (dB)
1.0
1.0 0.5 0 -0.5 -1.0 -1.5 -2.0 -2.5 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 VCACNTL (V) MGS = 111
GAIN MATCH: CHA to CHB, VCACNTL = 0.2V 50 45 40 35 30
45 40 35 30
GAIN MATCH: CHA to CHB, VCACNTL = 3.0V
Units
25 20 15 10 5 0
Units -0.36 -0.30 -0.24 -0.18 -0.12 -0.06 0 0.06 0.12 0.18 0.24 0.30 0.36 0.42 0.48 0.54 0.60 0.66 0.72 0.78 0.84 0.90
25 20 15 10 5 0
Delta Gain (dB)
4
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-0.07 -0.06 -0.05 -0.04 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.10 0.11 0.12 0.13 0.14 0.15 0.16 0.17 0.18
Delta Gain (dB)
VCA2618
SBOS254A
TYPICAL CHARACTERISTICS (Cont.)
At TA = +25C, VDD = 5V, load resistance = 500 on each output to ground, differential output (2Vp-p) MGS = 111, and fIN = 5MHz, unless otherwise noted.
GAIN vs FREQUENCY (VCACNTL = 3.0V) 50 45 40 35
Gain (dB) 40
GAIN vs FREQUENCY
MGS = 111
50
VCACNTL = 3.0V
MGS = 011
30
25 20 15 10 5 0 100k 1M Frequency (Hz) 10M 100M MGS = 001
Gain (dB)
30
20 VCACNTL = 1.6V 10 0 VCACNTL = 0.2V -10 100k 1M Frequency (Hz) 10M 100M
OUTPUT REFERRED NOISE vs VCACNTL 500 450 400 RS= 50 MGS = 111 600 550 500 450 400 350 300 250 200 150 100 50 0
INPUT REFERRED NOISE vs VCACNTL RS= 50
Noise (nV/Hz)
300 250 200 150 100 50 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 VCACNTL (V) MGS = 011
Noise (nV/Hz)
350
MGS = 111
MGS = 011 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 VCACNTL (V)
100
INPUT REFERRED NOISE vs RS
NOISE FIGURE vs RS 24 22 20 Noise Figure (dB) 18 16 14 12 10 8 6 4 2
Noise (nVHz)
10
1 1 10 RS () 100 1k
10
100 RS ()
1k
VCA2618
SBOS254A
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TYPICAL CHARACTERISTICS (Cont.)
At TA = +25C, VDD = 5V, load resistance = 500 on each output to ground, differential output (2Vp-p) MGS = 111, and fIN = 5MHz, unless otherwise noted.
60 55 50 45 40 35 30 25 20 15 10 5 0
NOISE FIGURE vs VCACNTL
HARMONIC DISTORTION vs FREQUENCY (Differential, 2Vp-p, MGS = 001) -30 -35
Harmonic Distortion (dBc)
VCACNTL = 0.2V, H2 VCACNTL = 0.2V, H3 VCACNTL = 3.0V, H2 VCACNTL = 3.0V, H3
-40 -45 -50 -55 -60 -65 -70 100k
Noise Figure (dB)
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 VCACNTL (V)
1M Frequency (Hz)
10M
HARMONIC DISTORTION vs FREQUENCY (Differential, 2Vp-p, MGS = 011) -30 -35 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 100k
-30 -35
Harmonic Distortion (dBc)
HARMONIC DISTORTION vs FREQUENCY (Differential, 2Vp-p, MGS = 111)
VCACNTL = 0.2V, H2 VCACNTL = 0.2V, H3 VCACNTL = 3.0V, H2 VCACNTL = 3.0V, H3
Harmonic Distortion (dBc)
-40 -45 -50 -55 -60 -65 -70 -75
VCACNTL = 0.2V, H2 VCACNTL = 0.2V, H3 VCACNTL = 3.0V, H2 VCACNTL = 3.0V, H3 1M Frequency (Hz) 10M
-80 100k
1M Frequency (MHz)
10M
HARMONIC DISTORTION vs FREQUENCY (Single-Ended, 1Vp-p, MGS = 001) -30 -35
Harmonic Distortion (dBc) Harmonic Distortion (dBc)
HARMONIC DISTORTION vs FREQUENCY (Single-Ended, 1Vp-p, MGS = 011) -30 -35 -40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 100k
VCACNTL = 0.2V, H2 VCACNTL = 0.2V, H3 VCACNTL = 3.0V, H2 VCACNTL = 3.0V, H3
-40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 100k VCACNTL = 0.2V, H2 VCACNTL = 0.2V, H3 VCACNTL = 3.0V, H2 VCACNTL = 3.0V, H3 1M Frequency (Hz) 10M
1M Frequency (Hz)
10M
6
VCA2618
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SBOS254A
TYPICAL CHARACTERISTICS (Cont.)
At TA = +25C, VDD = 5V, load resistance = 500 on each output to ground, differential output (2Vp-p) MGS = 111, and fIN = 5MHz, unless otherwise noted.
HARMONIC DISTORTION vs FREQUENCY (Single-Ended, 1Vp-p, MGS = 111) -30 -35
Harmonic Distortion (dBc)
Harmonic Distortion (dBc) 0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 -70 -75 -80
HARMONIC DISTORTION vs VCACNTL (Differential, 2Vp-p) MGS = 001, H2 MGS = 011, H2 MGS = 111, H2 MGS = 001, H3 MGS = 011, H3 MGS = 111, H3
-40 -45 -50 -55 -60 -65 -70 -75 -80 -85 -90 100k 1M Frequency (Hz)
VCACNTL = 0.2V, H2 VCACNTL = 0.2V, H3 VCACNTL = 3.0V, H2 VCACNTL = 3.0V, H3
10M
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 VCACNTL (V)
HARMONIC DISTORTION vs VCACNTL (Single-Ended, 1Vp-p) 0 -5 -10 -15 -20 -25 -30 -35 -40 -45 -50 -55 -60 -65 -70 -75 VCACNTL (V)
0
INTERMODULATION DISTORTION (Single-Ended, 1Vp-p, fIN = 10MHz, VCACNTL = 3.0V) -10 -20
Harmonic Distortion (dBc)
Amplitude (dB)
MGS = 001, H2 MGS = 011, H2 MGS = 111, H2 MGS = 001, H3 MGS = 011, H3 MGS = 111, H3
-30 -40 -50 -60 -70 -80 -90 -100
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
9.5
9.6
9.7
9.8
9.9 10.0 10.1 10.2 10.3 10.4 10.5 Frequency (MHz)
0 -10 -20
INTERMODULATION DISTORTION (Differential, 2Vp-p, fIN = 10MHz, VCACNTL = 3.0V)
0 -10 -20 Cross Talk (dB) -30 -40 -50 -60 -70 -80 -90
CROSS TALK vs FREQUENCY (Differential, 2Vp-p, MGS = 011)
VCACNTRL = 0V
Amplitude (dB)
-30 -40 -50 -60 -70 -80 -90 -100 9.5 9.6 9.7 9.8 9.9 10 10.1 10.2 10.3 10.4 10.5 Frequency (MHz)
VCACNTRL = 1.5V
VCACNTRL = 3.0V
1
6
11 Frequency (MHz)
16
21
VCA2618
SBOS254A
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TYPICAL CHARACTERISTICS (Cont.)
At TA = +25C, VDD = 5V, load resistance = 500 on each output to ground, differential output (2Vp-p) MGS = 111, and fIN = 5MHz, unless otherwise noted.
OVERLOAD DISTORTION vs FREQUENCY 0
2nd-Harmonic Distortion (dBc)
-10 -20
0.1V 0.25V 0.5V 1V
59 57 55
ICC vs TEMPERATURE
ICC (mA)
53 51 49 47 45
-30 -40 -50 -60 1M Frequency (Hz) 10M
-40
-25
-10
5
20
35
50
65
80
95
Temperature (C)
GROUP DELAY (1MHz Aperture) 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 1M
Group Delay (ns)
VCACNTL = 3.0V
VCACNTL = 0.2V
10M Frequency (Hz)
100M
8
VCA2618
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SBOS254A
OVERVIEW
The VCA2618 is a dual-channel, VGA consisting of three primary blocks, an Input Buffer, a VCA, and a PGA. All stages are AC coupled, with the coupling into the PGA stage being made variable by placing an external capacitor between the CP1 and CP2 pins. This will be discussed further in the PGA section. By using the internal coupling into the PGA, the result is a high-pass filter characteristic with cutoff at approximately 75kHz. The output PGA naturally rolls off at around 30MHz, making the usable bandwidth of the VCA2618 between 75kHz and 30MHz.
power-on time of the VCA2618 would be increased. If a decrease in the power-on time is needed, the value can be decreased to no less than 100pF.
VOLTAGE-CONTROLLED ATTENUATOR
The magnitude of the VCA input signal from the input buffer is reduced by a programmable attenuation factor, set by the analog VCA Control Voltage (VCACNTL) at pin 24. The maximum attenuation is programmable by using the three MGS bits (pins 21, 22, and 23). Figure 2 illustrates this dual-adjust characteristic.
0
VCA
PGA
VCA Attenuation (dB)
Channel A Input
Buffer
Channel A Output
Minimum Attenuation
VCA Control
Analog Control
Maximum Gain Select
-27
MGS
Channel B Input
Buffer
VCA
PGA
Channel B Output
-45 0
Maximum Attenuation 3.0V Control Voltage
FIGURE 1. Simplified Block Diagram of the VCA2618.
FIGURE 2. Swept Attenuator Characteristic. The MGS bits adjust the overall range of attenuation and maximum gain while the VCACNTL voltage adjusts the actual attenuation factor. At any given maximum gain setting, the analog variable gain characteristic is linear in dB as a function of the control voltage, and is created as a piecewise approximation of an ideal dB-linear transfer function. The VCA control circuitry is common to both channels of the VCA2618. The range for the VCACNTL input spans from 0V to 3V. Although overdriving the VCACNTL input above the recommended 3V maximum will not damage the part, this condition should be avoided.
INPUT BUFFER
The input buffer is a unity gain amplifier (gain of +1) with a bandwidth of 100MHz with an input resistance of approximately 600k. The input buffer isolates the circuit driving the VCA2618 inputs from the internal VCA block, which would present a varying impedance to the input circuitry. To allow symmetrical operation of the input buffer, the input to the buffer must be AC coupled through an external capacitor. The recommended value of the capacitor is 0.01F. It should be noted that if the capacitor value were increased, the
RS Input Q1A VCM Q1B Q2A Q2B Q3A Q3B Q4A Q4B Q5A Q5B Output
A1 B1 B2
A2
A3
A4
A5
FIGURE 3. Programmable Attenuator Section.
VCA2618
SBOS254A
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Attenuator Input RS
A1 to A10 Attenuator Stages QS
Attenuator Output
Q1 VCM A1 C1 A2 C2
Q2 A3 C3
Q3 A4 C4
Q4 A5 C5
Q5 A6 C6
Q6 A7 C7
Q7 A8 C8
Q8 A9 C9
Q9 A10
Q10
C10
V1
V2
V3
V4
V5
V6
V7
V8
V9
V10
Control Input
C1 to C10 Clipping Amplifiers
0dB
-4.5dB Attenuation Characteristic of Individual FETs
VCM - VT
0 V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
Characteristic of Attenuator Control Stage Output
OVERALL CONTROL CHARACTERISTICS OF ATTENUATOR 0dB
-4.5dB 0.3V Control Signal 3V
FIGURE 4. Piecewise Approximation to Logarithmic Control Characteristics.
10
VCA2618
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SBOS254A
PGA POST-AMPLIFIER
Figure 5 shows a simplified circuit diagram of the PGA block. As stated before, the input to the PGA is AC coupled by an internal capacitor. Provisions are made so that an external capacitor can be placed in parallel with the internal capacitor, thus lowering the usable low-frequency bandwidth. The lowfrequency bandwidth is set by the following equation:
MGS SETTING 000 001 010 011 100 101 110 111
ATTENUATOR GAIN VCACNTL = 0V to 3V Not Valid -27dB to 0dB -30dB to 0dB -33dB to 0dB -36dB to 0dB -39dB to 0dB -42dB to 0dB -45dB to 0dB
ATTENUATOR + DIFFERENTIAL PGA GAIN Not Valid 0dB to 27dB 0dB to 30dB 0dB to 33dB 0dB to 36dB 0dB to 39dB 0dB to 42dB 0dB to 45dB
(
1 2 * * 500k * (220pF + CEXTERNAL )
)
where CEXTERNAL is the external capacitor value in farads. Care should be taken to avoid using too large a value of capacitor, as this can increase the power-on delay time. As described previously, the PGA gain is programmed with the same MGS bits that control the VCA maximum attenuation factor. Specifically, the maximum PGA gain at each MGS setting is the inverse (reciprocal) of the maximum VCA attenuation at that setting. Therefore, the VCA + PGA overall gain will always be 0dB (unity) when the analog VCACNTL input is set to 0V (the maximum attenuation for VCA). For VCACNTL = 3V (no attenuation), the VCA + PGA gain will be controlled by the programmed PGA gain (27dB to 45dB in 3dB steps). For clarity, the gain and attenuation factors are detailed in Table I. The PGA architecture converts the single-ended signal from the VCA into a differential signal. Low input noise was also a requirement of the PGA design due to the large amount of signal attenuation that can be asserted before the PGA. At minimum VCA attenuation (used for small input signals), the
TABLE I. MGS Settings. input buffer noise dominates; at maximum VCA attenuation (large input signals), the PGA noise dominates. Note that if the PGA output is used single-ended, the apparent gain will be 6dB lower.
LAYOUT CONSIDERATIONS
The VCA2618 is an analog amplifier capable of high gain. When working on a PCB layout for the VCA2618, it is recommended to utilize a solid ground plane that is connected to analog ground. This helps to maximize the noise performance of the VCA2618. Adequate power-supply decoupling must be used in order to achieve the best possible performance. Decoupling capacitors on the VCACNTL voltage should also be used to help minimize noise. Recommended values can be obtained from the layout diagram of Figure 6.
VDD To Bias Circuitry RL Q1 Q11 Q12 Q9 RL
VCAOUTP VCM
Q3 RS1 RS2 +In Q4 Q2 Q14 Q13
Q8 VCM
VCAOUTN
Q7 Q10
-In
Q5
Q6
To Bias Circuitry
FIGURE 5. Simplified Block Diagram of the PGA Section with the VCA2618.
VCA2618
SBOS254A
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+5V 0.1F
1F
+5V 0.1F 0.1F
1F
1F
0.01F INA
28 1 INA
3
5 -OUTA +OUTA 25
VDDA VDDR VCM
0.01F +OUTA 0.01F -OUTA
26
VCA2618 -OUTB 0.01F INB 8 INB VDDB VBIAS VCNTL 13 1F 4 24 +OUTB 16 0.01F +OUTB 0.01F +OUTB
15
0.1F +5V 1F
0.1F
0.1F VCACNTL
FIGURE 6. VCA2618 Layout.
12
VCA2618
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SBOS254A
PACKAGE DRAWING PBS (S-PQFP-G32)
0,23 0,17 24 17
PLASTIC QUAD FLATPACK
0,50
0,08 M
25
16
32
9 0,13 NOM
1 3,50 TYP 5,05 SQ 4,95 7,10 SQ 6,90 1,05 0,95
8 Gage Plane
0,25 0,10 MIN 0,70 0,40 0- 7
Seating Plane 1,20 MAX 0,08 4087735/A 11/95 NOTES: A. All linear dimensions are in millimeters. B. This drawing is subject to change without notice.
VCA2618
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