THAT Analog Engine® Dynamics Processor THAT 4301, 4301A APPLICATI
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High-Performance Voltage Controlled Amplifier High-Performance RMS-Level Detector Three General-Purpose Opamps Wide Dynamic Range: >115 THD: <0.03% Cost: $4.39 (`000s) Surface-Mount Packages
THAT Analog Engine® Dynamics Processor
THAT 4301, 4301A APPLICATIONS
Compressors Limiters Gates Expanders De-Essers Duckers Noise Reduction Systems Wide-Range Level Meters
Description
THAT 4301 Dynamics Processor, dubbed "THAT Analog Engine," combines single active circuitry needed construct wide range dynamics processors. 4301 includes high-performance, exponentially-controlled VCA, log-responding RMS-level sensor three general- purpose opamps. provides opposing-polarity, voltage-sensitive control ports. Dynamic range exceeds typically 0.003% gain. 4301A, selected extremely high levels. detector provides accurate rms-to-dc conversion over dynamic range signals with crest factors opamp dedicated current-to-voltage converter VCA, while other used signal path control voltage processing. combination exponential gain control logarithmic detector response "decibel-linear" response simplifies mathematics designing control paths dynamics processors. This makes easy design audio compressors, limiters, gates, expanders, de-essers, duckers, noise reduction systems like. high level integration ensures excellent temperature tracking between detector, while minimizing external parts count.
THAT4301
Figure Block Diagram (pin numbers only)
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
Page
Rev. 9/10/01
SPECIFICATIONS Absolute Maximum Ratings 25°C)
Positive Supply Voltage (VCC) Negative Supply Voltage (VEE) Supply Current (ICC) Power Dissipation (PD) 75°C) Operating Temperature Range (TOP) Storage Temperature Range (TST) +70°C +125°C
Overall Electrical Characteristics
Parameter Positive Supply Voltage Negative Supply Voltage Positive Supply Current Negative Supply Current Thermal Resistance Symbol qJ-C SO-Package Conditions Units °C/W
Electrical Characteristics
4301 Parameter Input Bias Current Input Offset Voltage Input Signal Current Gain Control Gain-Control Constant EC+/Gain (dB) EC-/Gain (dB) Gain-Control TempCo Gain-Control Linearity Isolation DTCHIP Symbol IB(VCA) VOFF(VCA IIN(VCA) IOUT(VCA) 0.000V 25°C (TCHIP 55°C) gain +40dB ECRef TCHIP= 27°C gain -6.4 -6.5 +0.33 -6.4 +0.33 -6.6 mV/dB mV/dB %/°C Conditions Signal Signal -0.4 +0.4 4301A +0.4 Units mArms
EC+=SYM=-375mV, EC-=+375mV Rout 20kW gain gain gain Hz-20 Rout 20kW gain gain
Output Offset Voltage Change DVOFF(OUT)
Gain Cell Idling Current Output Noise
IIDLE en(OUT)
Total Harmonic Distortion
VIN= dBV, gain 0.003 0.007 0.003 0.007
specifications subject change without notice. Unless otherwise noted, TA=25°C, +15V, VEE= -15V; VCASYM adjusted kHz, gain. Test circuit section only from Figure
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
4301 Dynamics Processor
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SPECIFICATIONS (Cont'd.) Electrical Characteristics (Cont'd.)
4301 Parameter Symbol Conditions dBV, gain gain VOUT= dBV, gain +19.5 dBV, gain Symmetry Control Voltage VSYM minimum -2.5 +2.5 -2.5 0.05 0.09 +2.5 0.035 0.09 0.035 0.09 0.03 0.07 0.03 0.07 0.035 0.09 0.035 0.09 Total Harmonic Distortion (cont'd.) 4301A Units
Detector Electrical Characteristics
Parameter Input Bias Current Input Offset Voltage Input Signal Current Input Current Output Output Scale Factor Symbol (RMS) VOFF(RMS IIN(RMS) Iin0 20log(Iin/Iin0) 7.5mA 31.6nA< IIN< 25°C (TCHIP Scale Factor Match (RMS VCA) Gain 1mA<Iin (DET)<100mA Output Linearity fIN= 1kHz Iin< 100mA 100nA Iin< 316mA 31.6nA Iin< Rectifier Balance .001 1mA< 100mA Crest Factor pulse repetition rate error error error Maximum Frequency Additional Error 10mA 300nA Timing Current Range Voltage Timing Current Accuracy Filtering Time Constant Output Temp. Coefficient Output Current ICT/IT DTCHIP IOUT 7.5mA 7.5mA TCHIP 55°C TCHIP 27°C -300mV VOUT< +300mV 0.90
Conditions Signal Signal
Units
mV/dB
.985
1.015
1.30
0.026)
%/°C
0.33 ±100
Except noted, test circuit RMS-Detector section only from Figure THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
Page
Rev. 9/10/01
Specifications (Cont'd) Opamp Electrical Characteristics
Parameter Input Offset Voltage Input Bias Current Input Offset Current Input Voltage Range Symbol RS<10k VS=±7V ±15V (@50kHz) RL=10k RL=2k Output Voltage Swing VO@RL=5kW VO@RL=2kW Short Circuit Output Current Slew Rate Total Harmonic Distortion Conditions ±0.5 ±0.5 ±0.5 V/ms Units
±13.5
±13.5
Common Mode Rej. Ratio CMRR Power Supply Rej. Ratio Gain Bandwidth Product Open Loop Gain PSRR
1kHz, AV=1, RL=10kW 0.0007 0.003 0.0007 0.003 0.0007 0.003 1kHz, AV=-1, 0.0007 0.003
Input Noise Voltage Density Input Noise Current Density
fo=1kHz fo=1kHz
Test circuit opamps unity-gain follower configuration, with load resistor specified.
+15V
SIGNAL -15V
300K 47pF
20K0
47uF
20K0 SIGNAL
+15V
100n
47uF 100n -15V
THAT4301
10K0
22uF
2M00
10uF
-15V
Figure detector test circuit
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
4301 Dynamics Processor
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Name (ITime) Connection (CTime)
Name ECVCA Connection Connection Connection Connection Connection Connection Connection Connection Connection Connection
Table Connections
Ordering Information Plastic Plastic Surface Mount 4301P 4301S 4301PA Inquire
0-10
0-15
ITEM MILLIMETERS 24.8 Max. 24.2 +/-0.2 +/-0.2 7.62 +/-0.25 2.54 +/-0.15 0.46 +0.15 -0.1 +/-0.15 Typ. 0.98 Typ. 1.75 3.25 +/-0.15 Max. 0.51 Min. Min. 0.25 +0.15 -0.05 INCHES 0.98 0.95 +/-0.008 0.25 +/-0.008 0.30 +/-0.01 0.10 +/-0.006 0.02 +0.006 -0.004 0.04 +/-0.006 0.06 Typ. 0.04 Typ. 0.06 0.07 0.13 +/-0.006 0.19 Max. 0.02 Min. 0.11 Min. 0.01 +0.006 -0.002
ITEM
MILLIMETERS 15.4 10.3 0.05 Typ. 0.85 MAX. 0.15 0.15 0.05
INCHES 0.60 0.012 0.29 0.008 0.41 0.016 0.002 +0.004 -0.002 0.039 Typ. 0.033 Max. 0.09 0.006 0.006 0.004 0.031 0.008 +0.004 -0.002
Figure Plastic dual in-line package outline
Figure Plastic surface-mount package outline
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
Page
Rev. 9/10/01
Representative Data
Figure Gain Control Voltage (Ec-) 25°C
Figure 1kHz THD+Noise Input, Gain
Figure 1kHz THD+Noise Input, Gain
Figure 1kHz THD+Noise Input, Gain
Figure Frequency, Gain, 1Vrms Input
Figure Output Input Level,
Figure Departure from Ideal Detector Level
Figure Detector Output Frequency Various Levels
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
4301 Dynamics Processor
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Theory Operation
THAT 4301 Dynamics Processor combines THAT Corporation's proven Voltage-Controlled Amplifier (VCA) RMS-Level Detector designs with three general-purpose opamps produce Analog Engine useful variety dynamics processor applications. details theory operation RMS-Detector building blocks, interested reader referred THAT Corporation's data sheets 2150 Series VCAs 2252 RMS-Level Detector. Theory interconnection exponentially-controlled VCAs log-responding level detectors covered THAT Corporation's application note AN101, Mathematics Log-Based Dynamic Processors. which adjusted minimum signal distortion unity gain. controlled EC-, shown Figure combination SYM. This connection illustrated Figure Note that this figure shows only that portion circuitry needed drive positive control port; circuitry associated with OA1, detector been omitted.
Positive Control 47pF 20K0 300K 20K0 Signa
Brief
THAT 4301 based THAT Corporation's highly successful complementary log-antilog gain cell topology, used THAT 2150-Series VCAs, modular Series VCAs. THAT 4301 integrated using fully complementary, BiFET process. combination FETs with high-quality, complementary bipolar transistors (NPNs PNPs) allows additional flexibility design over previous efforts. Input signals currents pin. This virtual ground, normal operation input voltage converted input current appropriately sized resistor Figure Page Because offsets present input offset preceeding stages will modulated gain changes (thereby becoming audible thumps), input normally ac-coupled Figure output signal also current, inverted with respect input current. normal operation, output current converted voltage inverter OA3, where ratio conversion determined feedback resistor (R2, Figure connected between OA3`s output inverting input. signal path through noninverting. gain controlled voltage applied EC-, EC+, SYM. Gain decibels) proportional EC-, provided essentially same voltage (see below). constant proportionality -6.5 mV/dB voltage EC-, mV/dB voltage SYM. mentioned, proper operation, same voltage must applied SYM, except small (±2.5 bias applied between these pins. This bias voltage adjusts internal mismatches gain cell which would otherwise cause small differences between gain positive negative half-cycles signal. voltage usually applied external trim potentiometer Figure
Signal 47uF
THAT4301
Figure Driving Positive Control Port
While 4301's circuitry very similar that THAT 2150 Series VCAs, there several important differences, follows: Supply current fixed internally. Approximately available input output signal currents. (This also case 2150 Series when biased recommended.) signal current output internally connected inverting input on-chip opamp. order provide external feedback around this opamp, this node brought pin. control-voltage constant approximately mV/dB, primarily higher internal operating temperature 4301 compared that 2150 Series. input stage 4301 uses integrated P-channel FETs rather than bias-current corrected bipolar differential amplifier. Input bias currents have therefore been reduced.
Detector Brief
4301's detector computes level rectifying input current signals, converting rectified current logarithmic voltage, applying that voltage log-domain filter. output signal voltage proportional decibel-level value input signal current. Some component
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
Page
Rev. 9/10/01
twice input frequency) remains superimposed output. signal attenuated log-domain filter, which constitutes single-pole rolloff with cutoff determined external capacitor programmable current. VCA, input signals currents pin. This input virtual ground, resistor Figure normally used convert input voltages desired current. level detector capable accurately resolving signals well below (with input resistor). However, detector accurately track such low-level signals, coupling normally required. log-domain filter cutoff frequency usually placed well below frequency range interest. audio-band detector, typical value would time constant (t). filter's time constant determined external capacitor attached pin, internal current source (ICT) connected current source programmed pin: current mirrored with gain approximately 1.1. resulting time constant approximately equal 0.026 CT/IT. Note that, result mathematics detection, attack release time constants fixed their relationship each other. output detector scaled with same constant proportionality gain control: mV/dB. detector's reference (Iin0, input current which causes output), determined follows: detector output stage capable sinking sourcing Differences between 4301's RMS-Level Detector circuitry that THAT 2252 Detector follows: rectifier 4301 Detector internally balanced design, cannot balanced external control. 4301 will typically balance positive negative halves input signal within ±1.5%, extreme cases mismatch reach ±15%. However, mismatch will significantly increase
ripple-induced distortion dynamics processors over that caused signal ripple alone. time constant 4301's detector determined combination external capacitor (connected pin) internal, programmable current source. current source equal Normally, resistor connected directly 4301. reference point, level match, adjustable external current source. However, 2252, level match affected timing current, which, this case, drawn from mirrored internally input stage 4301 detector uses integrated P-channel FETs rather than bias-current corrected bipolar differential amplifier. Input bias currents therefore negligible, improving performance signal levels.
Opamps Brief
three opamps 4301 intended general purpose applications. opamps with slew rates approximately 2V/ms. bipolar input stages. However, design each optimized expected use. Therefore, most 4301, useful know major differences among these opamps. OA3, being internally connected output VCA, intended current-to-voltage conversion. input noise performance, 7.5nV complements that VCA, adding negligible noise unity gain. output section capable driving load within power supply rails, making possible this opamp directly output stage single-ended designs. quietest opamp three. input noise voltage, 6.5nV makes opamp choice input stages. Note that output drive capability limited order reduce chip's power dissipation) approximately comfortable driving loads more within power supply rails. intended primarily control-voltage processor. input noise parallels that OA3, output drive capability parallels that OA1.
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
4301 Dynamics Processor
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Applications
circuit Figure Page shows typical application THAT 4301. This simple compressor/limiter design features adjustable hard-knee threshold, compression ratio, static gain1. applications discussion this data sheet will center this circuit purpose illustrating important design issues. However, posslble configure many other types dynamics processors with THAT 4301. Hopefully, following discussion will imply some these possibilities. some reason, more than gain required when unity, then resistors skewed provide Note that feedback capacitor (C2) required stability. output approximately capacitance ground, which must neutralized feedback capacitor across gain controlled terminal, whereby gain will proportional negative voltage EC-. terminal grounded, terminal returned nearly ground small resistor (R3, trim (R5, allows small voltage applied terminal (300 kW). This voltage adjusts small mismatches within gain cell, thereby reducing even-order distortion products. adjust trim, apply input middle-level, middle-frequency signal good
Signal Path
mentioned section theory, input virtual ground with negative feedback provided internally. input resistor (R1, 20kW) required convert input voltage current within linear range 4301. (Peak input currents should kept under best distortion performance.) coupling capacitor (C1, strongly recommended block current from preceeding stages (and from offset voltage input VCA). current into will 47uF modulated varyTHRESHOLD gain VCA, showing outR12 383K "thumps". Note that conjunction 2M00 with will frequency limit 4k99 circuit.
100n 100n 10K0 1K43 22uF
20K0 10K0 300K 20K0 47pF
output connected OA3, configured inverting current-to-voltage converter. OA3`s feedback components (R2, determine constant current-to-voltage conversion. simplest deal with this recognize that when unity gain, input output voltage gain simply R2/R1, just case single inverting stage.
47uF
THAT4301
2M00
4k99 10uF 100N 590K GAIN
COMPRESSION
10K0
Figure Typical Compressor/Limiter Application Circuit
More information this compressor design, along with suggestions converting soft-knee operation, given AN100, Basic Compressor Limiter Design. designs AN100 based THAT Corporation's 2150-Series VCAs 2252 Detector, readily adaptable 4301 with only minor modifications. fact, circuit presented here functionally identical hard-knee circuit published AN100.
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
Page
Rev. 9/10/01
choice with this circuit) observe signal output. trim minimum THD.
RMS-Level Detector
detector's input similar that VCA. input resistor (R6, converts input voltage current within linear range 4301. (Peak detector input currents should kept under best linearity.) coupling capacitor (C3, recommended block current from preceeding stages (and from offset voltage input detector). current into detector will limit low-level resolution detector, will upset rectifier balance levels. Note that, with input circuitry, conjunction with will lower frequency limit detector. time response detector determined capacitor attached (C4, size current (determined negative power supply, -15V). Since voltage approximately circuit Figure produces current mirrored with gain pin, where available discharge timing capacitor (C4). combination produces filter with time constant equal approximately 0.026 CT/IT (~35 circuit shown). waveform will follow logged (decibel) value input signal envelope, plus offset about VBE). This allows polarized capacitor used timing capacitor, usually electrolytic. capacitor used should low-leakage type order significantly timing current. output stage detector serves buffer voltage remove offset, resulting output centered around input signals about output voltage increases every increase input signal level. This relationship holds over more than range input currents.
loop such that junction (the output threshold detector) sits -(R9/R8) RMSOUT. circuit Figure this RMSOUT. Negative signals from detector drive output positive, reverse biasing forward biasing CR1. this case, junction rests signal level informaion passed threshold detector's output. order vary threshold, R12, THRESHOLD control, provided. (383k adds ±39.2 current OA1`s summing junction, requiring same amount opposite-polarity current from detector output counterbalance 4.99 voltage across required produce counterbalancing current which represents change detector input level. Since detector's reference level center THRESHOLD pot's range would were MW), which provides offset. adds extra -7.5 OA1`s summing junction, which would counterbalanced 37.4 detector output. This corresponds offsetting THRESHOLD center this much approximately dBV. output threshold detector represents signal level above determined threshold, constant about mV/dB (from [R9/R8] mV/dB). This signal passed COMPRESSION control (R13), which variably attenuates signal passed OA2. Note that gain OA2, from wiper COMPRESSION control OA2`s output, R16/R15 (0.5), precisely inverse gain OA1. Therefore, COMPRESSION control lets user vary above-threshold gain between detector output output from zero maximum unity. gain control constant VCA, mV/dB, exactly equal output scaling constant detector. Therefore, maximum COMPRESSION, above threshold, every increase input signal level causes increase output OA2, which turn causes decrease gain. With this setting, output will increase despite large increases input level above threshold. This infinite compression. intermediate settings COMPRESSION, increase input signal level will cause less than decrease gain, thereby varying compression ratio. resistor included alter taper COMPRESSION better suit common use. linear taper used R13, compression ratio will middle rotation. However, compression above-threshold compressor very strong processing, often preferred midpoint. warps taper that compression occurs approximately midpoint R13`s rotation.
Control Path
compressor/limiter intended reduce gain signals rise above threshold. output detector represents input signal level over wide range levels, compression only occurs when level above threshold. configured variable threshold detector block envelope information low-level signals, passing only information signals above threshold. inverting stage with gain above threshold below threshold. Neglecting action THRESHOLD control (R12) associated resistors (R11 R10), positive signals from detector output drive output negative. This forward biases CR2, closing feedback
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
4301 Dynamics Processor
Page
GAIN control (R18) used provide static gain attenuation signal path. This control adds ±130 offset output (from which approximately change gain VCA. used attenuate noise OA2, resistors through used control path. these active passive components produce noise which passed control port VCA, causing modulation signal. itself, 4301 produces very little noise modulation, performance significantly degraded noisy components control voltage path.
about dBV. compression ratio varied from compression) And, static gain added Audio performance excellent, with running below 0.05% middle frequencies even with compression, input dynamic range over Perhaps most important, this example design only scratches surface large body applications circuits which constructed with THAT 4301. combination accurate, wide-dynamic-range, log-responding level detector with high-quality, exponentially-responding produces versatile powerful analog engine. opamps provided 4301 enable designer configure these building blocks with external components construct gates, expanders, de-essers, noise reduction systems like. further information, samples pricing, please contact address below.
Overall Result
resulting compressor circuit provides hard-knee compression above threshold with three essential user-adjustable controls. threshold compression varied over range from
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
Page
Rev. 9/10/01
Notes
THAT Corporation; Sumner Street; Milford, Massachusetts 01757-1656; Tel: (508) 478-9200; Fax: (508) 478-0990; Web: www.thatcorp.com
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