CEM3335

CEM3330 CES | Alldatasheet

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EXP. LINEAR ® Low Cost suonaL nese “ey Y a Controlled Amplifiers in a mlzlele =~ +i Single Package + oKS Bo oo BS AB SRL ons nay Mf Simultaneous Linear and SS eo = ~ Exponential Control Inputs tree} [vce * ® Wide Control Range: 120dB . ‘o sv : - . @ Very Accurate Control Scales = fw “1ovevser10V for Excellent Gain Tracking ve i \\ & Exceptionally Low Control at D ae . Voltage Feedthrough: -60dB ror Tweve<etOv minimum without trim, view ) we better than -80dB with trim aA COM OevecttOv ] ion: han 0. an Be L [vse oz, ra . Low Distortion Less than 0.1% ae = xceptionally Low Noise: i =) 7 avn wus Better than -100dB v i all | 1— Class B to Class A Operation ou ‘The h Lf Yt Ln Summing Signal and Linear fer - wll Vee tre 1K Control Inputs wart |ghes § fei Shoe L ® Current Outputs for Ease of ne Yous | esses ge JuoK Soo Pr oT Use in Voltage Controlled = wor |ePe] e _L 1 2-Pole Filters SIONAL = = = = oureur ong = iv EXP. LINEAR ® Can Be Used in VCO and nese TY ‘Tie thew rut VCF Control Paths Without . oe Causing Shift @ £15 Volt Supplies

eee; Electrical Characteristics Application Hints A Linear Control Range 100 130 4B volt £10% Zener diode has been (input plus output) Class A #800 +1400 - HA run off virtually any negative Exponential Control Scale Sensitivity 28 3.0 3.2 [mv/aB supply voltage. If the negative Tempco of Exponential Control Scale +3000 © +3300» +3600 | ppm supply is between -4.5 and -6.0 Tempco of Linear Control Scale = #100 +300 | ppm volts, it may be connected directly to the negative supply | Exponential Control Scale Error? - 0.3 1 4B pin (pin 5). For voltages greater | Linear Control Scale Error! O<IeL<100HA | = 9.3 15 % than -7.5 volts, a series current i Cell Current Gain Vge0 83 1 1.2 limiting resistor must be added Current Gain Tempco Vg=0 - +100 4300 | ppm between pin 5 and the supply. Log Converter Output lcc=Iner | 3 0 45 | mv Its value is calculated as follows: i Output Voltage Compliance 73 = 413.5 Vv Ree = (Veg - 7.2)/lee i Untrimmed Distortion? Clase 8 - as 5 % where leg is 010 for idle Trimmed Distortion? Class B ~ 0.2 os | % currents less than 10A, .012 Class A - 05 02 % for idle currents between 10uA Untrimmed Control Feedthrough? Class B - 02 og uA and BOu/h and -O Sonn ie Class A ~ 7 25) HA 200uA. (See Selection of ' Trimmed Control Feedthrough? Class B - 01 8 | yA Quiescent Operating Current). Class A = u S| uA Although the circuit was Output Noise Current in 20KHz Class B - 1.2 3.5 |nARMS designed for a positive supply Signal Current Bandwidth4 Class B 30 100 - KHz operated from any voltage : Class A 100 350 - KHz between +9 and +18 volts with Signal Current Slew Rate Class B 60 150 BALLS little effect on performance. Class A 400 750 — | wAMuS . - Crosstalk Between VCAs F=10KHz | -60 -70 = dB Basic Operation Internal Bias Current at Signal & Linear Class B 80 175 350 | nA Each of the two voltage con- Control Inputs Class A 130 300 600 nA trolled amplifiers consists of a i Exponential Contro! Input Current WoL = 100K, 4 08 13 BA variable gain cell and, in the case Linear Control Input Offset Voltage 7 #3 +15 mv of the 3330, a log converter as Signal input Offset Voitage 15 5 +5 mv well (see Block Diagrams). The Positive Supply Current ClassB* | og 13 24 | ma gain cell is the current-in, : : ? current-out type, accepting a Class A 24 27 3.7 | ma " “ bipolar input current, ty, and i Positive Supply Range +9 - +18 v providing a bipolar output cur- i Negative Supply Range® 45 = -18 | Vv rent, Ip, with the following } relationship: i Note 1: From current gains of +20dB to -80dB. Peak cell current is fess than 1004 v i Note 2: Output signal is 10dB below clipping and is at a frequency of 1KHz. Vg =0 lo =-liye” oNr Vr = KT/q i Note 3: Current gain varies from unity to maximum attenuation (>110dB) i Note 4: Peak Output Current is £200uA. where Vg is the voltage applied j Note 5: Current limiting resistor required for negative voltages greater than -6 volts. to the direct control input of Note 6: Class B is defined at an idle current of 14A; Class A is at an idle current of 100uA. each gain cell (pin 2 and pin 15 on the 3330, pin 2 and pin 11 i on the 3335). For the 3330, the log con- i verter generates the logarithm of . the linear control input current, H 2 i

Absolute Maximum Ratings | tex, (pin 7 and pin 12) while transmitting the exponential Voltage B Hi ; t n ge Between Voc and Veg Pins +24V,-0.5V control input, Vee, (pins 6 and ce £E . 14) unchanged to its output. Voltage Between Veg and Ground Pins +18V,-0.5V i The transfer function for each Voltage Between Vee and Ground Pins -6.0V,+0.5V log converter s Voltage Between Output and Distortion Trim i cL or Ground Pins +18V,-0.5V i Voie =-Vr In —— + Vee = Vg 7 . : TREF Voltage Between All Other Pins and Ground Pin +6,0V Hl where Iper is the current Current Through Any Pin 440mA | sourced into the direct control Storage Temperature Range -5B°C to +150°C input. Since the output of the . 95% 6, i fog converter internally connects Operating Temperature Range 26°C to+75°C to the direct control input of the gain cell, the overall current i gain of the gain cell is given by: lect, «let .¢-Veer CEM3335 Circuit Block and Connection Diagram io = HIN * — * IRee For proper operation, the linear EXP. control current, Ic, and refer- SIGNAL cutt, SIGNAL : ae ouTPUT INPUT i ence current, Iper, are positive INPUT } in polarity; that is, they flow Y NE5534 into the device. A negative input wix i current for Icy will simply teln 1 shut the gain completely off, 7 3 6. ra - while a negative reference cur- e;* rent should be avoided. The 4 DOS uF signal input current may, of 51K TNS14 | /UUSHT +15V course, be either polarity. = = The Block Diagrams show 64 O63 Or 6 Ow ds oe typical external components 4 __| connections to the devices. The signal inputs and the linear aA control inputs are virtual ground CELL summing nodes; therefore, the IS —L signal input currents and linear Tor ) BALL = control currents may be ac- view i curately generated from their EB i respective voltages simply REG.& | with resistors terminating at BIAS ADJ. these nodes. Note that these virtual ground inputs also allow NY [| multiple input voltages to be O1 2 O3 Oa O OE O7 i mixed (linearly added) on-chip Rg 51K 1 by merely adding more input z resistors. RiDLe 6.8K Although the voltage com- Reel Rez) N91 R i . A V4 1 Ri i pliance of the gain cell outputs KS 33K 100K EE ane i ranges from -0.3V to Voc ~ L e082 1.5V, best results are obtained NESS30 = = Hl by feeding the outputs into SIGNAL = = ‘ « ; -18V virtual ground inputs. Thus, in OUTPUT oe seu the Block Diagrams, the output INPUT currents are converted to | voltages with external op amps. i 3 :

10.0 CELL CURRENT GAIN VARIES aw

FROM UNITY TO MAX. ATTEKUATION 50 “a0 20 2 ____ i :* TATE CLATAT /

210 No TRIM, J 2 {

5 as / S —etnas nevow cuierinc 5 / woe g ‘oor rat / a ~SL S oz onty 7 1KHZ va 80. a ee = on Va 1 2 5 10 20 50 100-200 ZZ USTORTION ILE CURRENT IN pA Taine ONLY 0s — EVEN HARMONIC DISTORTION ‘israntion + 1

0 WwPUT TRIM, |

ao} OV _N 1 2 5 1 20 so 100 200 SNA, IDLE CURRENT In A ~ cupping san 10K _ coNTAOL FEEDTHROUGH 2 SQL = aKHe = 2000 2 so ~ i CELL CURRENT GaIN 3 N. Fovats UNITY 3 ~N 1000] tg = 2200.8 z Sanne 3 ae ma = = ~ e500] ° @ 10d8 BELOW CLIPPING é 0 % 200 10 tT 2 S10 2 60 100200 : 12 eT) OLE CURRENT IN uA IDLE CURRENT IH uA . ODD HARMONIC DISTORTION (OUTPUT CURRENT SLEW RATE : 800 ceLL current catn #0 ceLL cuRRENT GAIN i < EQUALS UNITY LL CURRENT Gf = red 2 +600] 32 0 5 sao . Ee ng ee | & (MULTIELY-BY 2.0 e BAW. = 16 = 16KHZ :

3 FOR PEAK CELt CURRENT) |

2200 n “110 | i? a a ET) 2 $10 20 80 100 200 i IDLE CURRENT IN wa, IDLE CURRENT IN A i PERK OUTPUT CURRENT BEFORE CLIPPING Noise OUTPUT : FIGURE 1: VCA PERFORMANCE VS.1DLE CURRENT : 4 i

eee. Selection of for these conditions is unity, but determines the most negative Component Values the voltage gain for the circuit value of Voge required to gen- | . + is Re/R| and may be greater erate the maximum voltage gain. Selection of the input and or less than unity. Note also that If the exponential input is not | output resistor values requires the current gain may be made used, then it may be grounded ‘ consideration of the preferred greater than unity for inputs less (VgE = 0), and only the values i Iovels of the device as wellas ‘ah VIN MAX- oo ea ees lusaled # . to obtain the maximum gain the available input voltages and Although Ri and Re have factor desired output voltage. Ingen. been selected using maximum factor. i eral, the input signal current Aut and output conditions, —_—_ Selection of the i should be made as large as pos- operate at least 6 to 20 GB Quiescent Operating sible to obtain the best signal below these wraxitourn levels Current to polse rao. enavet for (corresponding to 100uA or less A unique feature of the device i eak output currents greater input and output currents) for is that the quiescent standby, bs , best distortion performance. or idle, current of the signal- i in several hundred microam- C ¢ Y : res, distortion begins to in- With the values of Ry and Re carrying transistors can be set peres, distort ‘ selected, the maximum linear anywhere between one and 1 crease significantly, until! the ' total cell current (input peak control current, I¢_, and most several hundred microamperes, negative exponential control thus effectively allowing the current plus output peak i voltage, Vee (Vg in the case of user to set the operation of the current) exceeds the maximum * i ified ii ‘fi the 3335), are selected to give gain cells anywhere between value specified in the specifica- ~ . i tions for Igp. At this point, the maximum desired voltage Class B and Class A. Since the i tipping ocna Pour gain in accordance to the follow- quiescent operating point : clipping occurs, resulting in § core cts : severe distortion ing equations: affects all VCA characteristics, orien it i hile worsen- i For optimum noise per- Re Ict -Vog/v- improving some wi Ps formance, it is recommended Ay 3330 = +e Yce/VT ing others, the idle current is i . R, leer selected to optimize those that the input resistor, Ry, ti i t to th t be selected so that the maximum 9, eetticular a ication © the peak input signal voltage causes R pai As chowe in the aa hs of % the peak cell current to flow a, =F. .Vo/Vr leant rnin the graphs o' i + Py : V 3335 e Figure 1, increasing the idle in the input: Ry} "i j current decreases distortion, Rr= Vin wax/% lop The maximum gain is only improves slew rate, and in- . limited by either the total cell creases available output cur- Note that the input could current exceeding Icp, or exces- _rent, but all at the expense of handle up to 6dB more current, sive noise and DC output shift increased noise and greater but the cell current gain would with cell current gains much control voltage feedthrough. have to be reduced so signifi- greater than unity (>+40dB). Thus, if the application is to cantly to prevent clipping, that For greatest linear scale control the level of low fre- the signal to noise ratio would accuracy, the maximum value of — quency control signals where actually be degraded. (Output Io should be restricted to control voltage rejection is i noise increases roughly by the 100A or less, although currents critical, then the VCA is best square root of an increase in up to 300uA can be used with operated Class B. For the pro- cell current gain). If more than increasing error. For best distor- _ cessing of audio signals, however, : ‘one signal is being summed in tion performance, the reference the VCA should be operated the input, then the total of all current, Ine, should also be Class AB to Class A, with the : peak input currents should be set between 50uA and 200uA; best compromise between dis- no greater than ¥% lop. Next, the it may be generated simply with tortion, noise and bandwidth. ? output resistor, Rr, is selected aresistor to Voc. The linear The quiescent idle current is so that the desired maximum for control input resistor , Rec, is set the same for both VCAs by i the peak output voltage before thus selected so that the maxi- placing a resistor between the Fi clipping is produced with the mum available linear control idle adjust pin (pin 8 on the } maximum input signal. Thus, voltage produces the desired 3330, pin 6 on the 3335) and Re-v, Ih\\ maximum value for let. the leg pin (pin 5). Figure 2 FeO MAXI TCP Finally, the selected value of shows the idle current versus Note that the cell current gain IReF together with Io. max the value of this resistor. With 5 i

$$ j internal resistors. In most cases, the peak signal level at which it i 200 this idle current tolerance is is desired to trim the distortion, + acceptable because the VCA The output voltage is measured : % parameters will vary toamuch _to four digits with a DVM for 00 3 lesser extent. However, the idle each of the three input condi- i | current may be set more pre- tions, and the trim adjusted i 50 cisely by measuring the idle so that the output voltage 4 | current and adjusting the value change is the same going from i

2 Of Ripce with a trim pot until the grounded to positive input :

<” = the desired value is obtained. as it is going from the grounded i 2 5 The idle current is measured by _to negative input. i Ew -|)_ measuring the output current Although the second harmonic & maximuns | with no signal input and at a may be trimmed out to better aw current gain of unity while than 80dB at almost any gain : 2 recat putting roughly -0.5 to -1.5. setting and input signal level, it voit on the distortion trim pin is best to perform the trimming 20 {pins 3 and 17 on the 3330, at a current gain of zero and umimun pins 3 and 13 on the 3335). input signal level around 10dB Hi 3 below the clipping point. This 10 = Trimming of the Second procedure will yield, in general, ‘| Harmonic Distortion the best distortion performance “s When operating the VCAs tess St al input levels and gain i than Class A, internal transistor ha hese thet 10 20 Bd bef az mismatches will cause the gain Eh tn t) And 12K 5K TOK 20K SK 100K 200K during the positive portion of {bping at the output). And } " f 4 since in the case of the music } ProLe IN the input signal to differ from ond speech signals, the last 15 | DLE CURRENT vs at during the negative portion, 4 FIGURE 2: I WS. IDLE ADJUST RESISTOR thes neotenic eeporaion ‘© 2a shouldbe reserved for no resistor (Ripe =) the distortion (predominantly acceptable. idle current is typically at 1uA second). In Figure 3 is shown a ‘As most of the odd order and the VCAs will operate graph of typical untrimmed harmonic distortion is due to Class B. second harmonic distortion crossover distortion, there is no As can be seen from Figure 2, (distortion trim pins connected avg trim it outs rt may be i the idle current may vary sig- to ground) versus the idle reduced only by increasing the nificantly from device to device current. This distortion may be i415 Current for any given value of Ripte, aceoptable in some applications, 7 h 9% 2 of th ut will have to be trimme: . . due to the 25% toleranc e out in others. Trimming is Optimizing the Bandwidth accomplished by adjusting the As can be seen from the Block : * | voltage on the distortion trim Diagrams, the log converters are “ pins (pins 3 and 17 on the stabilized with a series 1K re- 7 3330, pins 3 and 13 on the sistor and .014:F capacitor com- = 3335) somewhere between pensation network from the Baal ez ~~ ue | ETOmV, as shown in Figure 4. linear control input to ground, FS aN The even harmonic distortion while each of the gain cells | 5 \\. may be trimmed to near mini- may be compensated with a 2 0 \\ mum with the following simple .0054F capacitor from the com- a \\ procedure: The signal input is pensation pins (pins 9 and 11 s @ 1008 BELOW\\, alternately switched between on the 3330, pins 7 and 9 on i * 0 CLIPPING ground, a positive voltage source the 3335) to ground. This gain 1 N (such as a battery) and a nega- cell compensation is good for i tive voltage source of the exact low frequency control applica- 0 a same magnitude (best accom- tions, but may result in inade- : ro ee) 30100 209 lished by simply reversing'the quate large signal bandwidth for IDLE CURRENT IN uA, leads to the positive voltage quality audio applications. i FIGURE 3: SECOND HARMONIC DISTORTION, UNTRIMED source). The value of the voltage Figure 5 shows an improved ° . source is selected to be equal to compensation technique for i 6 i

greater bandwidths and slew and no temperature compensa- } rate: By placing a series 1K tion is necessary. +15V L j resistor and .01F capacitor To use the 3330 for exponen- - } network from the signal input tial gain control only, the entire 1002 i to ground, the .0O5uF com- log converter may be bypassed, 100K: A5oK j pensation capacitors may be reducing the number of external i reduced to 150 pF, resulting in components and potential errors 9.4 9000909 6 the bandwidths and slew rate introduced by the log converter. i shown in Figure 1. This is accomplished by simply av }) leaving the linear and exponential Md Control inputs - control inputs open, and apply- TOTO OOO OO As was discussed earlier, the ing the exponential control 100k linear control input resistor, voltage directly to the IRer pin 150K" Ret, should be selected so that {Which is also the direct input, rane the linear control current reaches WG to the gain cell) as shown in ay L amaximum of S0HA to 200A, Figure 6. The scale sensitivity is = This level is low enough so as the same as that of the exponen- FIGURE 4: DISTORTION TRIM not to cause significant control tial input to the log converter, Fy scale non-linearity, but high and therefore requires the same enough to swamp out the considerations as discussed maximum control voltage rejec- effects of the internal input above. oo tion is to simply set the gain to bias current. Since the actual For best distortion per- maximum and adjust the pot current controlling the linear formance, it is recommended for zero DC quiescent output gain is the input control current _that the impedance at both current, (The DC output current i minus this bias current, the the distortion adjust inputs at zero gain is always zero.) input control voltage at which and direct control inputs (3330 The other method for mini- the gain becomes zero is given or 3335) be kept below several mizing control voltage feed- by: hundred ohms. through is to palance the two i circuit halves by adjusting the i Veto = !eRet +Vos Trimming of the Control second harmonic distortion trim i This cut-off point may be Voltage Feedthrough discussed above. This method, i increased by injecting a small The shift in the quiescent DC ay ough usually reducing the i constant negative current into output voltage as the gain is storie “A ow tine of the un: the control input, or decreased changed is due to several factors. timmed value, will not adjust by injecting a small positive One cause is the internal bias current into the input. current at the signal current As the scale sensitivity of the input, being only of concern at ie exponential control inputs on idle currents less than 104A. = = both the 3330 and 3335 are The other cause is the same po- ra Ry re 18mV/-6dB, an attenuation tential imbalance between the OF 1K . = network will in most cases by two signal processing halves 150pF | required. An increasing positive Which also is responsible for po 00 odo 4 2 control voltage decreases the even order harmonic distortion. 31 “insta gain. Thus, there are two methods prevention The basic gain cell is fully for minimizing the contro! i 4 9 DIODES temperature compensated. The voltage feedthrough: One is to OOO OOOO only first order temperature inject an adjustable DC current i effect is the exponential control into the signal current input pin, OF 1K L- : factor tempco (1/Vy). This as shown in Figure 7. The range Ry y effect may be substantially of this current should be roughly T reduced by using a +3300ppm equal to plus and minus the idle = = = tempco resistor (Tel Labs Q81) current, (For idle currents less SIGNAL i for Reet, shown in the Block than 5yA, it is not necessary that INPUT i Diagrams. If only the linear this current be adjustable to FIGURE 5: GAIN CELL COMPENSATION Fi control input is to be used, then _ negative values.) The best tech- FOR LARGER BANDWIDTH the exponential input is grounded nique for adjusting this trim for 7 i