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general description the MAX3657 is a transimpedance preamplifier for receivers operating up to 155mbps. the low noise, high gain, and low power dissipation make it ideal for class-b and class-c passive optical networks (pon). the circuit features 14na input-referred noise, 130mhz bandwidth, and 2ma input overload. low jitter is achieved without external compensation capacitors. operating from a +3.3v supply, the MAX3657 con- sumes only 76mw power. an integrated filter resistor provides positive bias for the photodiode. these fea- tures, combined with a small die size, allow easy assembly into a to-46 header with a photodiode. the MAX3657 includes an average photocurrent monitor. the MAX3657 has a typical optical sensitivity of -38dbm (0.9a/w), which exceeds the class-c pon require- ments. typical overload is 0dbm. the MAX3657 is avail- able in die and 3mm x 3mm 12-pin thin qfn packages. applications optical receivers (up to 155mbps operation) passive optical networks (pon) sfp/sff transceivers bidi transceivers features 14na rms input-referred noise 54k ? transimpedance gain 130mhz (typ) bandwidth 2ma p-p input current?dbm overload capability 76mw (typ) power dissipation 3.3v single-supply operation average photocurrent monitor MAX3657 155mbps low-noise transimpedance amplifier ________________________________________________________________ maxim integrated products 1 ordering information 19-2834; rev 1; 8/03 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. * future product? ontact factory for availability. ** dice are designed to operate over a -40? to +110? junction temperature (t j ) range, but are tested and guaranteed at t a = +25?. pin configuration appears at end of data sheet. part temp range pin-package MAX3657etc* -40? to +85? 12 thin qfn MAX3657e/d -40? to +85? die** typical application circuit filt in gnd 1 f 1 f to-46 header *optional component out+ out- mon v ccz r filt c filt 3.3v c out r load 200 ? r mon * limiting amplifier max3964 MAX3657 v cc c vcc1 c vcc2
MAX3657 155mbps low-noise transimpedance amplifier 2 _______________________________________________________________________________________ absolute maximum ratings dc electrical characteristics (v cc1 = +2.97v to +3.63v, 200 ? load between out+ and out-, t a = -40? to +85?. typical values are at v cc = +3.3v, t a = +25?, unless otherwise noted.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. power-supply voltage ...........................................-0.5v to +6.0v input continuous current ................................................?.5ma voltage at out+, out- ...................(v cc - 1.5v) to (v cc + 0.5v) voltage at filt, mon .................................-0.5v to (v cc + 0.5v) continuous power dissipation 12-pin qfn (derate 14.7mw/? above +70?) ...........1176mw operating temperature range 12-pin qfn ........................................................-40? to +85? operating junction temperature range die .................................................................-40? to +150? storage temperature range .............................-55? to +150? lead temperature (soldering, 10s) .................................+300? die attach temperature...................................................+400? parameter symbol conditions min typ max units supply current i cc 23 34 ma input bias voltage v in i in 1ma 1 1.3 v transimpedance linear range 0.95 < linearity < 1.05, referred to gain at 1a p-p input 2a p-p small-signal transimpedance z 21 differential output, i in < 200na p-p 44 54 65 k ? output common-mode voltage ac-coupled outputs v cc - 0.225 v output resistance (per side) r out single-ended output resistance 82 100 118 ? maximum differential output voltage v out ( max ) i in = 2ma p-p, v out = (v out +) - (v out -) 170 250 450 mv p-p filter resistor r filt 640 800 960 ? dc input overload 1 1.5 ma monitor nominal gain g nom v cc = +3.3v, +25 c (note 2) 0.8 1 1.2 a/a i in = 100a to 1ma -1.5 +1.5 die -1.5 +2.2 i in = 5a qfn package -3.0 +2.7 i in = 2a die only -4.0 +3.4 monitor gain stability (note 3) ? g i in = 1a die only 2.0 db ac electrical characteristics (v cc = +2.97v to +3.63v, 200 ? load between out+ and out-, c in = 0.5pf, c filt = 400pf, c vcc2 = 680pf, t a = -40 c to +85 c. typical values are at v cc = +3.3v, t a = +25 c, unless otherwise noted.) (note 1) parameter symbol conditions min typ max units small-signal bandwidth bw -3db relative to gain at 1mhz 110 130 mhz low-frequency cutoff -3db, i in = 1a 5 25 khz ac overload 2ma p-p pulse-width distortion pwd 300na p-p i in 2ma p-p 22 ps p-p f = 100mhz (note 4) 15 input-referred noise current i n f = 117mhz 14 na rms rms noise density f = 100mhz 1.3 pa/ hz monitor bandwidth i in = 1a 5 khz
MAX3657 155mbps low-noise transimpedance amplifier _______________________________________________________________________________________ 3 note 1: die parameters are production tested at room temperature only, but are guaranteed by design from t a = -40 c to +85 c. ac characteristics guaranteed by design and characterization. note 2: g nom = i mon (1ma) / 1ma. note 3: stability is relative to the nominal gain at v cc = +3.3v, t a = +25 c. ? g(i in ) db = 10 log 10 [ i mon (i in ) ] / [ i mon (1ma) - g nom x (1ma - i in )], v mon 2.1v, input t r , t f > 550ps (20% to 80%). note 4: total noise integrated from 0 to f. ac electrical characteristics (12-pin qfn) (v cc = +2.97v to +3.63v, r load = 200 ? , c in = 1.0pf, c filt = 1000pf, c vcc2 = 0.01f, t a = -40 c to +85 c. typical values are at v cc = +3.3v, t a = +25 c, unless otherwise noted.) (note 1) parameter symbol conditions min typ max units small-signal bandwidth bw -3db relative to gain at 1mhz 95 mhz low-frequency cutoff -3db, i in = 1a 5 25 khz ac overload r 10 1.6 ma pulse-width distortion pwd 1a p-p i in 2ma p-p 22 ps p-p f = 50mhz (note 4) 5 input-referred noise current i n f = 100mhz 13 na rms rms noise density f = 100mhz 1.3 pa/ hz typical operating characteristics (MAX3657 e/d. v cc = 3.3v, c in = 0.5pf, t a = +25 c, unless otherwise noted.) 35 40 50 45 55 60 -40 0 20 -20 40 60 80 small-signal transimpedance vs. temperature MAX3657 toc01 ambient temperature ( c) transimpedance gain (k ? ) 0.2 a p-p 1.0 a p-p 0 30 20 10 70 60 80 50 40 90 100 -40 0 20 -20 40 60 80 supply current vs. temperature MAX3657 toc02 ambient temperature ( c) supply current (ma) 0.7 0.9 0.8 1.1 1.0 1.2 1.3 -40 0 20 -20 40 60 80 input bias voltage vs. temperature MAX3657 toc03 ambient temperature ( c) input bias voltage (v)
output eye diagram (1.0 a electrical input) MAX3657 toc10 1ns/div 50mv -50mv 10mv output eye diagram (100 a electrical input) MAX3657 toc11 1ns/div 200mv -200mv 40mv output eye diagram (1ma electrical input) MAX3657 toc12 1ns/div 200mv -200mv 40mv MAX3657 155mbps low-noise transimpedance amplifier 4 _______________________________________________________________________________________ typical operating characteristics (continued) (MAX3657 e/d. v cc = 3.3v, c in = 0.5pf, t a = +25 c, unless otherwise noted.) 100 0 0.1 1.0 10 100 1000 10,000 pulse-width distortion vs. input current amplitude 20 MAX3657 toc04 input signal amplitude ( a) pulse-width distortion (ps) 40 60 80 10 30 50 70 90 +85 c +25 c -40 c -400 -200 -300 0 -100 100 200 300 400 -20 -10 -5 -15 0 5 10 15 20 differential output voltage vs. input current MAX3657 toc05 input current ( a) output voltage (mv p-p ) v filt = gnd r load = open z 21 = 108k ? r load = 200 ? z 21 = 54k ? r load = 100 ? z 21 = 36k ? frequency response frequency (hz) output magnitude (db ? ) 98 80 83 86 89 95 92 100 1m 100m 10k 1k 100k 10m 1g MAX3657 toc06 differential output single-ended output 0 50 25 175 150 225 250 200 100 75 125 275 0.1 0.5 0.7 0.3 0.9 1.1 1.3 1.5 bandwidth vs. capacitance MAX3657 toc07 capacitance (pf) bandwidth (mhz) t j = +110 c t j = +25 c t j = -40 c 0 10 20 15 25 30 35 0.2 0.4 0.6 0.8 1.0 1.2 1.4 input-referred rms noise vs. capacitance MAX3657 toc08 capacitance (pf) input-referred noise (na rms ) t j = -40 c t j = +25 c t j = +110 c 1.2 0 0.1 1.0 10 100 1000 10,000 input-referred rms noise vs. dc input current 0.2 MAX3657 toc09 dc current in ( a) input-referred noise (na rms ) 1.0 0.4 0.6 0.8 t j = +110 c t j = +25 c t j = -40 c
MAX3657 155mbps low-noise transimpedance amplifier _______________________________________________________________________________________ 5 output eye diagram (-30dbm optical input) MAX3657toc13 1ns/div 2 23-1 prbs 6mv/ div zarlink 1a358 photodiode + MAX3657 output eye diagram (-1dbm optical input) MAX3657toc14 1ns/div 20mv/ div zarlink 1a358 photodiode + MAX3657 2 23-1 prbs input impedance vs. frequency frequency (hz) magnitude of input impedance ( ? ) 800 300 350 400 450 500 550 600 750 700 650 100 1m 100m 10k 1k 100k 10m 1g MAX3657 toc15 t j = +25 c t j = -40 c t j = +110 c small signal typical operating characteristics (continued) (MAX3657 e/d. v cc = 3.3v, c in = 0.5pf, t a = +25 c, unless otherwise noted.) pin name function 1, 9, 11 n.c. no connection. do not connect. 2 gnd negative supply voltage. both gnd and gndz must be connected to ground. 3 gndz negative supply voltage. both gnd and gndz must be connected to ground. 4 mon photocurrent monitor. this is a current output. connect a resistor between mon and ground to monitor the average photocurrent. 5 in signal input. connect to photodiode anode. 6 filt filter connection (optional). use to bias the photodiode cathode. an internal 800 ? on-chip resistor is connected between this pin and v ccz , an external decoupling capacitor connected to this pin forms a filter (see the design procedure section). 7 v ccz power-supply voltage. both v cc and v ccz must be connected to the supply. 8 v cc power-supply voltage. both v cc and v ccz must be connected to the supply. 10 out+ positive data output. this output has 100 ? back termination, increasing input current causes out+ to increase. 12 out- negative data output. this output has 100 ? back termination, increasing input current causes out- to decrease. pin description
MAX3657 155mbps low-noise transimpedance amplifier 6 _______________________________________________________________________________________ detailed description the MAX3657 transimpedance amplifier is designed for 155mbps fiber optic applications. the functional dia- gram of the MAX3657 is comprised of a transimped- ance amplifier, a voltage amplifier, a dc-cancellation circuit, and a cml output buffer. transimpedance amplifier the signal current at the input flows into the summing node of a high-gain amplifier. shunt feedback through resistor r f converts this current into a voltage. schottky diodes clamp the output signal for large input currents (figure 1). voltage amplifier the voltage amplifier provides additional gain and con- verts the transimpedance amplifier single-ended output signal into a differential signal. output buffer the output buffer provides a reverse-terminated volt- age output and is designed to drive a 200 ? differential load between out+ and out-. for optimum supply- noise rejection, the MAX3657 should be terminated with a differential load. the MAX3657 single-ended outputs do not drive a dc-coupled grounded load. the outputs should be ac-coupled or terminated to v cc . if a single- ended output is required, both the used and the unused outputs should be terminated in a similar manner. dc-cancellation circuit the dc-cancellation circuit uses low-frequency feed- back to remove the dc component of the input signal (figure 2). this feature centers the input signal within the transimpedance amplifier s linear range, thereby reducing pulse-width distortion. the dc-cancellation circuit is internally compensated and does not require external capacitors. this circuit minimizes pulse-width distortion for data sequences that exhibit a 50% mark density. a mark density signifi- cantly different from 50% causes the MAX3657 to gen- erate pulse-width distortion. grounding the filt pin disables the dc-cancellation circuit. for normal opera- tion, the dc-cancellation circuit must be enabled. the dc-cancellation current is drawn from the input and creates noise. for low-level signals with little or no dc component, the added noise is insignificant. however, amplifier noise increases for signals with significant dc component (see the typical operating characteristics ). voltage amplifier output buffer out+ r out r out out- r f v ccz mon lowpass filter r out filt in dc-cancellation circuit transimpedance amplifier enable +1.0v MAX3657 functional diagram
MAX3657 155mbps low-noise transimpedance amplifier _______________________________________________________________________________________ 7 photocurrent monitor the MAX3657 includes an average photocurrent monitor. the current at mon is approximately equal to the dc cur- rent at in. best monitor accuracy is obtained when data input edge time is longer than 500ps. design procedure select photodiode noise performance and bandwidth are adversely affected by stray capacitance on the tia input node. select a low-capacitance photodiode to minimize the total input capacitance on this pin. the MAX3657 is optimized for 0.5pf of capacitance on the input. assembling the MAX3657 in die form using chip and wire technology provides the lowest capacitance input and the best possible performance. select c filt supply voltage noise at the cathode of the photodiode produces a current i = c pd ? v/ ? t, which reduces the receiver sensitivity (c pd is the photodiode capaci- tance). the filter resistor of the MAX3657, combined with an external capacitor, can be used to reduce the noise (see the typical application circuit ). current gen- erated by supply-noise voltage is divided between c filt and c pd . to obtain a good optical sensitivity, select c filt > 400pf. select supply filter the MAX3657 requires wideband power-supply decou- pling. power-supply bypassing should provide low impedance between v cc and ground for frequencies between 10khz and 200mhz. use lc filtering at the main supply terminal and decoupling capacitors as close to the die as possible. select r mon connect a resistor between mon and ground to moni- tor the average photocurrent. select r mon as large as possible: where i monmax is the largest average input current observed. select coupling capacitors a receiver built with the MAX3657 has a bandpass fre- quency response. the low-frequency cutoff due to the coupling capacitors and load resistors is: select c couple so the low-frequency cutoff due to the load resistors and coupling capacitors is much lower than the low-frequency cutoff of the MAX3657. the coupling capacitor should be 0.1f or larger, but 1.0f is recom- mended for lowest jitter. refer to maxim application note hfan-1.1: choosing ac-coupling capacitors for more information. layout considerations figure 3 shows a suggested layout for a to header for the MAX3657. wire bonding for high-current density and reliable operation, the MAX3657 uses gold metalization. for best results, use gold-wire ball-bonding techniques. use caution if attempting wedge bonding. die-size is 41 mils x 48 mils, (1040m x 1220m) and die thickness is 15 mils (380m). the bond pad is 94.4m x 94.4m and its metal thickness is 1.2m. refer to maxim application note hfan- 8.0.1: lfc xr xc term load couple = 1 2 r mon monmax 2.1v i = figure 1. MAX3657 limited outputs amplitude output (large signals) time output (small signals) figure 2. effects of dc cancellation on input amplitude input from photodiode time input after dc cancellation
MAX3657 155mbps low-noise transimpedance amplifier 8 _______________________________________________________________________________________ in filt m o n vccz v cc o ut+ o ut- g ndz g n d c vcc c filt c vcc photodiode case is ground photodiode case is ground c filt case 4-pin to header 5-pin to header in filt mon vccz vcc out+ out- gndz gnd case figure 3. suggested to header layout
MAX3657 155mbps low-noise transimpedance amplifier _______________________________________________________________________________________ 9 understanding bonding coordinates and physical die size for more information on bond-pad coordinates. applications information optical power relations many of the MAX3657 specifications relate to the input- signal amplitude. when working with optical receivers, the input is sometimes expressed in terms of average optical power and extinction ratio. figure 4 and table 1 show relations that are helpful for converting optical power to input signal when designing with the MAX3657. optical sensitivity calculation the input-referred rms noise current (i n ) of the MAX3657 generally determines the receiver sensitivity. to obtain a system bit-error rate (ber) of 1e-10, the signal-to-noise ratio must always exceed 12.7. the input sensitivity, expressed in average power, can be estimated as: where is the photodiode responsivity in a/w and i n is the rms noise current in amps. for example, with pho- todiode responsivity of 0.9a/w, an extinction ratio of 10 and 15na input-referred noise, the sensitivity of the MAX3657 is: actual results may vary depending on supply noise, out- put filter, limiting amplifier sensitivity, and other factors (refer to maxim application note hfan-3.0.0: accurately estimating optical receiver sensitivity ). input optical overload overload is the largest input the MAX3657 accepts while meeting the pulse-width distortion specification. optical overload can be estimated in terms of average power with the following equation: for example, if photodiode responsitivity is 1.0a/w, the input overload is 0dbm. optical linear range the MAX3657 has high gain, which limits the output for large input signals. the MAX3657 operates in a linear range for inputs not exceeding: for example, with photodiode responsivity of 0.9a/w and an extinction ratio of 10 the linear range is: linear range ax xx x dbm dbm = ? ? ? ? ? ? = ? 10 211 209 9 1000 28 log . linear range ar xr x dbm e e = + ? ? ? ? ? ? ? 10 21 21 1000 log () () overload ma x x dbm = ? ? ? ? ? ? 10 2 2 1000 log sensitivity xnax xawx x dbm dbm = ? ? ? ? ? ? = ? 10 12 7 15 11 209 9 1000 38 log . ./ sensitivity xi x r xxr x dbm ne e = + ? ? ? ? ? ? ? 10 12 7 1 21 1000 log .() () pp r r avg e e 12 1 = + ppp p r r in avg e e == + ? ? 102 1 1 * assuming a 50% average mark density. parameter symbol relation average power p avg p avg = (p0 + p1)/2 extinction ratio r e r e = p1/p0 optical power of a 1 p1 optical power of a 0 p0 p0 = 2p avg /(r e + 1) optical modulation amplitude p in table 1. optical power relations* figure 4. optical power relations p0 p1 p avg time optical power pp r r avg e e 12 1 = + ppp p r r in avg e e == + ? 10 2 1
MAX3657 interface schematics equivalent output interface the MAX3657 has a differential cml output structure with 100 ? back termination (200 ? differentially). figure 5 is a simplified diagram of the output interface. the output current is divided between the internal 100 ? resistor and the external load resistance. because of the cml structure, the maximum output-signal ampli- tude is affected by load impedance. note that the inter- nal back termination is 100 ? single ended and external termination is recommended to interface the device to 50 ? test equipment. for example, if single-ended oper- ation in a 50 ? system is required, first match the output of the MAX3657 to the 50 ? controlled impedance by placing a 100 ? pullup resistor in parallel with the out- put. then establish similar loading conditions on the unused output. note that the loading conditions affect the overall gain of the MAX3657. figures 6a, 6b, and 6c show alternate interface schemes for the MAX3657. pad coordinates table 2 lists center-pad coordinates for the MAX3657 bond pads. refer to maxim application note hfan- 8.0.1: understanding bonding coordinates and physical die size for more information on bond-pad coordinates. 155mbps low-noise transimpedance amplifier 10 ______________________________________________________________________________________ out+ 4.5ma out- v cc v cc v cc r out 100 ? r out 100 ? figure 5. equivalent output interface table 2. bond-pad information coordinates pad name xy bp1 out- 47.2 994.8 bp2 gnd 52.2 484.6 bp3 gndz 52.2 357.7 bp4 mon 395.5 47.2 bp5 in 522.3 47.2 bp6 filt 648.5 47.2 bp7 n.c. 808.5 49.9 bp8 v ccz 808.5 176.8 bp9 v cc 808.5 303.7 bp10 out+ 808.5 994.8 bp11 n.c. 741.1 859.9
MAX3657 155mbps low-noise transimpedance amplifier ______________________________________________________________________________________ 11 cml output stage 100 ? *component not required if l < 10cm v cc l 100 ?? 100 ?? 50 ?? 50 ?? 100 ? MAX3657 50 ? 50 ? differential cml input stage figure 6a. 50 ? dc-coupled interface cml output stage 100 ? note: the parallel combination at the unused output can be replaced by a single equivalent 33 ? resistor. *component not required if l < 10cm l 100 ?? 100 ?? 50 ?? 100 ? v cc 50 ? MAX3657 50 ? single-ended input stage figure 6b. 50 ? dc-coupled single-ended output interface
MAX3657 155mbps low-noise transimpedance amplifier 12 ______________________________________________________________________________________ filt 800 ? v cc figure 7. filt interface mon v cc figure 8. mon interface cml output stage 100 ? *component not required if l < 10cm l 100 ?? 100 ?? 50 ?? 100 ? v cc MAX3657 50 ? load to ground 50 ? 50 ? figure 6c. 50 ? ac-coupled single-ended output interface
MAX3657 155mbps low-noise transimpedance amplifier ______________________________________________________________________________________ 13 chip topography 2 1 3 456 7 8 9 10 11 out- out+ gnd gndz mon in n.c. filt n.c. v ccz v cc 0.048in 1.219mm 0.041in 1.041mm chip information transistor count: 417 process: silicon bipolar substrate: connected to gnd die size: 1.04mm x 1.22mm top view 12 out- 11 n.c. 10 out+ 45 in 6 filt 1 2 gnd 3 9 8 7 gndz n.c. v cc v ccz MAX3657 n.c. mon qfn *exposed pad is connected to gnd pin configuration
MAX3657 155mbps low-noise transimpedance amplifier 14 ______________________________________________________________________________________ package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages . 12x16l qfn thin.eps package outline 12 & 16l, qfn thin, 3x3x0.8 mm 2 1 21-0136 c rev. document control no. approval proprietary information title: 0.10 c 0.08 c 0.10 m c a b d d/2 e/2 e a1 a2 a e2 e2/2 l k e (nd - 1) x e (ne - 1) x e d2 d2/2 b l e l c l e c l l c l c - a - - b -
MAX3657 155mbps low-noise transimpedance amplifier maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 15 ? 2003 maxim integrated products printed usa is a registered trademark of maxim integrated products. package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages . 1. dimensioning & tolerancing conform to asme y14.5m-1994. exposed pad variations document control no. 21-0136 package outline 12 & 16l, qfn thin, 3x3x0.8 mm proprietary information approval title: c rev. 2 2 2. all dimensions are in millimeters. angles are in degrees. 3. n is the total number of terminals. 4. the terminal #1 identifier and terminal numbering convention shall conform to jesd 95-1 spp-012. details of terminal #1 identifier are optional, but must be located within the zone indicated. the terminal #1 identifier may be either a mold or marked feature. 5. dimension b applies to metallized terminal and is measured between 0.20 mm and 0.25 mm from terminal tip. 6. nd and ne refer to the number of terminals on each d and e side respectively. 7. depopulation is possible in a symmetrical fashion. 8. coplanarity applies to the exposed heat sink slug as well as the terminals. 9. drawing conforms to jedec mo220 revision c. notes:

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