VCA610_08 TI1 | Alldatasheet
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Technical content
DESCRIPTION
The VCA610 is a wideband, continuously variable, voltage-controlled gain amplifier. It provides linear-dB gain control with high impedance inputs. It is designed to be used as a flexible gain-control element in a variety of electronic systems. The VCA610 has a gain-control range of 77dB (–38.5dB to +38.5dB) providing both gain and attenu- ation for maximum flexibility in a small SO-8. The broad attenuation range can be used for gradual or controlled channel turn-on and turn-off for applica- tions in which abrupt gain changes can create artifacts or other errors. In addition, the output can be disabled to provide –77dB of attenuation. Group delay varia- tion with gain is typically less than ±2ns across a bandwidth of 1MHz to 15MHz. The VCA610 has a noise figure of 3.5dB (with an R S of 200Ω ) including the effects of both current and voltage noise. Instantaneous output dynamic range is 70dB for gains of 0dB to +38.5dB with 1MHz noise bandwidth. The output is capable of driving 100Ω . The high-speed, 300dB/µs, gain-control signal is a unipolar (0V to –2V) voltage that varies the gain linearly in dB/V over a –38.5dB to +38.5dB range. VCA610
FEATURES
G WIDE GAIN CONTROL RANGE: 77dB G SMALL PACKAGE: SO-8 G WIDE SIGNAL BANDWIDTH: 30MHz G LOW VOLTAGE NOISE: 2.2nV/ √Hz G FAST GAIN SLEW RATE: 300dB/ µs WIDEBAND VOLTAGE CONTROLLED AMPLIFIER
APPLICATIONS
G OPTICAL DISTANCE MEASUREMENT G AGC AMPLIFIERS G ULTRASOUND G SONAR G ACTIVE FILTERS G LOG AMPLIFIERS G IF CIRCUITS G CCD CAMERAS The VCA610 is designed with a very fast overload recovery time of only 200ns. This allows a large signal transient to overload the output at high gain, without obscuring low-level signals following closely behind. The excellent overload recovery time and distortion specifications optimize this device for low- level doppler measurements. +5V –5V VOUT –In +In VC Gain Control VCA610 VCA610 Copyright © 2000, Texas Instruments Incorporated SBOS013A Printed in U.S.A. November, 2000 www.ti.com
Input Voltage Noise V C = –2V 2.2 ✻ nV/√Hz Input Current Noise V C = 0 to –2V 1.4 ✻ pA/√Hz Noise Figure V C = –2V, RS =200Ω 3.5 ✻ dB INPUT Input Impedance Common-Mode 1 || 1 ✻ M Ω || pF Bias Current All Gains 6 ✻ µA Offset Current All Gains 2 ✻ µA Differential Voltage Range (1) ✻ Common-Mode Voltage Range ±2.5 ✻ V Common-Mode Rejection 50 ✻ dB GAIN Specified Gain Range –38.5 +38.5 ✻✻ dB Gain Accuracy(2) –2V ≤ VC ≤ 0V ±0.6 ±2.3 ±2 ±4d B Gain Accuracy Temperature Drift T A = –25°C to +85°C ±0.01 ✻ dB/°C Gain with Output Disabled +0.1V ≤ VC ≤ +2.0V, f = 1MHz –80 ✻ dB GAIN CONTROL Gain Scaling Factor –38.5dB ≤ G ≤ +38.5dB 38.5 ✻ dB/V Control Voltage (VC)G = –38.5dB (VC = 0V) to 0 –2 ✻✻ V +38.5dB (VC = –2V) Bandwidth –3dB 1 ✻ MHz Slew Rate 77dB Gain Step 300 ✻ dB/µs Settling Time: 1% V IN = 10mVDC , ∆ G = 77dB 800 ✻ ns Input Impedance 1 || 1 ✻ M Ω || pF Input Bias Current All Gains 2 ✻ µA Output Offset Change(3) ∆ G = 77dB ±30 ±75 ✻ ±125 mV FREQUENCY RESPONSE Bandwidth, Small-Signal –3dB, All Gains 30 ✻ MHz Bandwidth, Large-Signal V O = 1Vp-p, G ≥ 0dB 25 ✻ MHz Group Delay Unit-to-Unit Variation 0dB ≤ G ≤ +38.5dB f = 1 to 15MHz ±1 ✻ ns –38.5dB ≤ G < 0dB f = 1 to 15MHz ±2 ✻ ns Output Slew Rate V O = 1Vp-p 60 ✻ V/µs Overload Recovery(4) 200 ✻ ns Two-tone Intermodulation Distortion(5) Small-Signal –50 ✻ dBc Two-tone, 3rd-Order IMD Intercept(5) Small-Signal 15 ✻ dBm OUTPUT Voltage Swing(1) Output Voltage Limit ✻ Short-Circuit Current Continuous to Common ±80 ✻ mA Instantaneous Dynamic Range (IDR)(6) G = 0dB to +38.5dB V O = 1.5Vp-p 70 ✻ dB Offset G = –38.5dB ±2 ±30 ✻✻ mV Output Resistance f = 1MHz, All Gains 10 ✻ Ω POWER SUPPLY Specification ±5V Recommended ±4.5 ±5.5 ✻✻ V PSR G = 0dB 40 50 ✻ dB Quiescent Current –26/+30 ±32 ✻✻ mA TEMPERATURE Specification Applies to Temperature Drift Specs –25 +85 ✻✻ °C Operation –40 +125 ✻✻ °C Thermal Resistance, θJA U, UA 125 ✻ °C/W SPECIFICATIONS ELECTRICAL All specifications at VS = ±5V, RL = 500Ω , RS = 0Ω , and TA = +25°C, unless otherwise noted. VCA610UA VCA610U PARAMETER CONDITIONS MIN TYP MAX MIN TYP MAX UNITS ✻ Specifications same as VCA610UA. NOTES: (1) See Input/Output Range discussion in the Applications Information section (Figure 2). (2) Gain is laser trimmed and tested at control voltages of 0V to –2V in 200mV steps; VIN = 1Vp-p for VC > –1V gains less than 0dB; VOUT = 1V for VC < –1V. (3) Output offset change from offset at VC = 0V. (4) Gain = +40dB; Input step of 2V to 2mV; time required for ouput to return from saturation to linear operation. (5) VIN = 7mVp-p, VOUT = 700mVp-p (250mVrms); Output Power = –10dBm/tone, equal amplitude tones of 5MHz ±500Hz, VC = –2V. See Typical Performance Curves. (6) With RS = 0Ω , and noise bandwidth of 1MHz. IDR = 20 log(VORMS /(eORMS • √BW)) where VORMS is rms output voltage, eORMS is output noise spectral density, and BW is noise bandwidth. Symmetrical to Ground (±10%)
Junction Temperature (T ELECTROSTATIC DISCHARGE SENSITIVITY This integrated circuit can be damaged by Electrostatic Discharge (ESD). Burr-Brown recommends that all inte- grated circuits be handled with appropriate precautions. Failure to observe proper handling and installation proce- dures can cause damage. ESD damage can range from subtle performance degrada- tion 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. –VS +V S –In VOUT VCA610 GND +In Gain Control, VC No Internal Connection PACKAGE SPECIFIED DRAWING TEMPERATURE PACKAGE ORDERING TRANSPORT PRODUCT PACKAGE NUMBER RANGE MARKING NUMBER (1) MEDIA VCA610U SO-8 182 –40°C to +125°C VCA610U VCA610U Rails " " " " " VCA610U/2K5 Tape and Reel VCA610UA SO-8 182 –40°C to +125°C VCA610UA VCA610UA Rails " " " " " VCA610UA/2K5 Tape and Reel NOTE: (1) Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /2K5 indicates 2500 devices per reel). Ordering 2500 pieces of VCA610U/2K5 will get a single 2500-piece Tape and Reel. PACKAGE/ORDERING INFORMATION
TYPICAL PERFORMANCE CURVESTYPICAL PERFORMANCE CURVES At VS = ±5V, RL = 500Ω , RS = 0Ω , and TA = +25°C, unless otherwise noted. SMALL-SIGNAL RESPONSE vs GAIN Frequency (MHz) 0.1 1.0 10 100 Gain (dB) 48.125 38.5 28.875 19.25 9.625 –9.625 –19.25 –28.875 –38.5 –48.125 VC = –2.0V VC = –1.5V VC = –1.0V VC = –0.5V VC = 0V Large Signal, VO = 1Vp-p GAIN vs CONTROL VOLTAGE Control Voltage, VC (V) Gain (dB) 57.75 38.5 19.25 –19.25 –38.5 –57.75 –77 Output Disabled for +0.1V ≤ VC ≤ +2V Specified Operating Range GAIN CONTROL RESPONSE Frequency (Hz) Normalized Response (dB) –12 –15 10k 100k 1M 10M 100M FEEDTHRU WITH OUTPUT DISABLED Frequency (MHz) Disabled Gain (dB) –17 –37 –57 –77 –97 0.1 1 10 100 Output Disabled for +0.1V ≤ VC ≤ +2V VOLTAGE AND CURRENT NOISE vs GAIN Gain (dB) 10k 100 Voltage Noise (nV/√Hz) 100 0.1 Current Noise (pA/√Hz) Output Voltage Noise Input Current Noise Input-Referred Voltage Noise NOISE FIGURE vs SOURCE RESISTANCE Source Resistance (Ω ) NF (dB) 10 100 1k 10k 100k NF dB = 10 log 1 +en 2 + (inR S)2 4kTR S
TYPICAL PERFORMANCE CURVES (Cont.) At VS = ±5V, RL = 500Ω , RS = 0Ω , and TA = +25°C, unless otherwise noted. GROUP DELAY vs GAIN Gain (dB) Group Delay (ns) 1MHz 10MHz 15MHz 2-TONE, 3rd-ORDER INTERMODULATION INTERCEPT vs GAIN Gain (dB) Intercept Point (dBm) –10 –20 –30 –40 –38.5 –19.25 0 19.25 38.5 10MHz 1MHz OUTPUT OFFSET CHANGE vs GAIN Gain (dB) Output Offset Change (mV) 150 100 –50 –100 –150 –38.5 –19.25 0 19.25 38.5 Change from Output Offset at G = –38.5dB Specification Limit Low Grade High Grade PSR and CMR vs FREQUENCY Frequency (Hz) Rejection (dB) 10k 100k 1M 10M 100M –PSR +PSR CMR G = 0dB LARGE-SIGNAL RESPONSE Time (µs) 0 100 200 Output Voltage (mV) +500 –500 “DIAMOND PATTERN ” RESPONSE Time (µs) 02 55 0 Output Voltage (mV) +500 –500
tion of the offset effects produces the greatest output offset. would otherwise couple to the amplifier input. required, a ground-referenced bipolar voltage is needed. to prevent saturation of internal circuitry. FIGURE 3. Optional Offset Adjustment and Control Line 3a) Optional Offset Adjustment. power supplies to the inputs should be minimized. bypassed to ground as close as possible to the amplifier pins. vide excellent results due to their low lead inductance. mize signal distortion and overload delay time. gain-control overdrive signal. TABLE I. Output Signal Compression.
FIGURE 6. Two Series Connected VCA610s Expand the Gain Range and Improve Noise Performance. FIGURE 7. This AGC Circuit Maintains a Constant Output Amplitude for a 1000:1 Input Range. CA1 serves as a low-noise, fixed-gain preamp. –77dB to 0dB segment of the composite gain range. 1 through R3 that determine attack and release times. the attack time of this AGC correction. overload of the VCA610’s gain control circuit.
0.1 VDC
FIGURE 9. Driving the Gain Control Pin of the VCA610 with FIGURE 8. Adding Wein-Bridge Feedback to the AGC Circuit of Figure 7 Produces an Amplitude-Stabilized Oscillator. W1 , RW2 ) and two capacitors (CW1 , CW2 ). decreasing impedance of the CW1 decreases this factor. amplifier. The AGC circuitry establishes this gain level. negative, increasing the amplifier gain from its minimum. tude at VR by holding the amplifier gain at a level of three. produces amplitude modulation of the oscillator output. amp with low offset voltage and low gain drift. input voltage VIN connected at the op amp inverting input.
FIGURE 12. A Voltage-Tunable High-Pass Filter Produces a Response Zero Variable from 1Hz to 10kHz. Y = V C , making the circuit output voltage VO = VOA V C /10. 1 to 100 avoids the reduction in output swing capability.
- The resistance of this bypass, R3, serves only to
circuit produces a response zero at fZ = 1/2πR 1C. G and sets the circuit’s bandwidth at BW = √(fC /2πR 1C). constrains the input voltage to VI ≤ VOAL /G.
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