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this document is for maintenance purposes only and is not recommended for new designs
the sl1454 is a wideband fm demodulator designed to operate with a carrier frequency between 70mhz and 150mhz. the internal circuitry of the device is similar to that of the sl1452 except that the quadrature demodulator operates at the input frequency. features n excellent threshold n negligible differential gain and phase errors n video bandwidth suitable for high definition tv n high sensitivity and wide dynamic range n wide operating frequency range: 70 to 150mhz ordering information sl1454 na dp (14-lead plastic dil package) sl1454 wideband linear fm detector for satellite tv 2039-21 dp8 0v demodulator coil demodulator coil 0v input signal input ref v cc video output 1 2 3 4 8 7 6 5 sl1454 fig. 1 pin connections - top view absolute maximum ratings operating temperature range supply voltage, pin 6 input voltage, pin 7 or 8 storage temperature junction temperature 2 10 c to 1 80 c 7v 25v p-p 2 55 c to 1 150 c 1 175 c fig. 2 block diagram demodulator input ref 8 7 input signal input amplifier 3 2 quadrature demodulator components video amplifier 5 video output 6 v cc 1 0v 4 0v 1k 1k 2k 2k 70p 2p 2p advance information
2 sl1454 electrical characteristics these characteristics are guaranteed over the following conditions (unless otherwise stated): t amb = 1 25 c, v cc = 1 45v to 1 55v, q = 2, f = 140mhz characteristic conditions value typ. max. min. units pin supply current, i cc video output voltage video bandwidth minimum operating frequency maximum operating frequency input voltage intermodulation differential gain differential phase signal-to-noise ratio v cc = 5v d f = 214mhz p-p product of input modulation: f = 44mhz, d f = 214mhz p-p and f = 6mhz, d f = 3mhz p-p (pal colour and sound subcarriers). d f = 214mhz p-p. demodulated staircase referred to input staircase before modulation. demodulated colour bar waveform referred to waveform before modulation. ratio of output with d f = 214mhz p-p at 1mhz to output rms noise in 10mhz bandwidth with d f = 0. ma v p-p mhz mhz mhz mvrms db % deg db 35 300 6 5 5 8 8 8 5 5 5 5 10 70 30 04 10 70 150 2 50 ,6 1 ,6 1 32k quadrature coil 0v 2ma 0v 400 400 18k 1 5v 0v 3ma 25v 25v 2k 2k 1k 1k 70p 87 0v 2ma 175k 640 0v 1 5v 23 5 ? ? ? ? ? input signal 2p 2p input ref video output fig. 3 input/output interface circuits
3 sl1454 82 sl1454 4 3 2 1 5 6 7 8 40n 33p 1n 1 5v 01 m 1n video output 140mhz input 0v q = 2 fig. 4 typical application for 140mhz reducing the video output level is to incorporate a dual tuned circuit in the quadrature network. this can easily be done by capacitatively coupling another parallel tuned circuit to the normal quadrature tuned circuit. fig. 6 shows an example of this form of dual tuned circuit, both sections having the same q factor and coupling capacitors chosen to give the best linearity (linear phase response). fig.5(b) shhows the advantages of the dual tuned circuit. the effect of varying the q factor of the dual tuned circuit on bandwidth is also described by table 1. example design a quadrature circuit to demodulate a 140mhz carrier with centre with 21.4mhz peak to peak deviation, modulated with a 25hz triangular dispersion wave form of 2mhz peak to peak deviation. the video bandwidth required is 9mhz. choose l = 40nh then c = 32.309pf (nearest preferred value 33pf) the next value to choose is the q factor. as dispersion is employed, linearity over the full 21.4mhz range needs to be optimised. the graphs in fig.5 show that either a single tuned circuit with a q of 2, or a dual tuned circuit with a q of 3 is adequate. the dual tuned circuit has the advantage that the peak to peak video output is larger than that of the single tuned circuit, but extra components are required. both circuits have a larger video bandwidth than the required 9mhz. the value of the damping resistor for the required q is calculated below: for q = 2 total r = q2 p fl = 2 3 2 3 p 3 140 3 10 6 3 004 3 10 2 6 = 703717 w allowing for the internal 800 w resistance between pins 2 and 3 (see fig. 3), the external resistance should be 77.1 w . choose 82 w .. for q = 3 total r = q2 p fl = 3 3 2 3 p 3 140 3 10 6 3 004 3 10 2 6 =10556 w allowing for the internal 800 w resistance, the external resistance should be 1215 w , so choose 120 w . when using a dual tuned circuit the value of coupling capaci- tor is dependent of the q factor. table 2 gives a guide to the values needed for best linearity. 1 2 p= lc application notes the sl1454 fm demodulator has a very simple application with very low external component count. this is demonstrated by the applications circuit diagram fig. 4, but as with most integrated circuits, particularly those working at high frequencies, some attention to good rf layout techniques and correct component selection will ensure optimum results. a good layout can usually be ensured by the simple precau- tion of keeping all components close to the sl1454, maintaining short lead lengths and ensuring a good low impedance ground plane. double sided board layout enables these objectives to be easily met, but is not essential for satisfactory operation. all coupling and decoupling capacitors should be chosen for low impedance characteristics at high frequencies. a fairly stable component should be selected for the quadrature coil tuning capacitor to prevent excessive drift. the power supply decoupling capacitor from pin 6 to ground should be 0.1 m f minimum, but the input coupling and decoupling values can be smaller, about 330pf being adequate. the only remaining components to be selected are those forming the quadrature circuit on pins 2 and 3 and some care in the determination of values for these is required if maximum performance is to be obtained. choose suitable values for l and c to resonate at the intermediate frequency you are applying to the device, using: f = the value of c should by greater than 15pf to prevent stray capacitance effects introducing errors and distortion of the demodulation s-curve, but the use of very large capacitances with small inductance values will lower the impedance of the tuned circuit at the required q value, reducing the drive level to the demodulator and thereby restricting the video output available. once suitable l and c values have been determined, the working q for the quadrature circuit should be set, the q value determining the video output level and bandwidth. video output is proportional to q whereas video bandwidth is inversely proportional. the effect of q variations on video bandwidth and amplitude can be determined from table 1 and the graphs in fig.5. a value for total damping resistor value to obtain the required q can be calculated from: r = q2 p fl the internal 800 w resistance between pins 2 and 3 must be allowed for when calculating r. as can be seen from the graphs in fig.5, for the demodulator to demodulate a 20mhz peak to peak deviation signal with optimum linearity a very low q value needs to be chosen ( , 2). however, this has the disadvantage of producing a demodulator with a very low peak to peak video output level. one way of increasing the linear region of the s-curve without
4 sl1454 q 6 4 2 bandwidth 10mhz 11mhz 12mhz table 1 q 6 4 3 coupling capacitor 39pf 56pf 10pf table 2 25 20 15 0 120 130 140 150 160 frequency (mhz) dc output voltage (v) q = 4 q = 2 q = 6 25 20 15 0 120 130 140 150 160 frequency (mhz) dc output voltage (v) q = 4 q = 2 q = 6 fig. 5 output voltage v. input frequency (a) single tuned quadrature network (b) double tuned quadrature network 120 sl1454 4 3 2 1 5 6 7 8 40n 33p 1n 1 5v 01 m 1n video output 140mhz input 0v q = 3 10p 10p 33p 40n 120 fig. 6 example of double tuned quadrature circuit
5 sl1454 notes
6 sl1454 headquarters operations gec plessey semiconductors cheney manor, swindon, wiltshire sn2 2qw, united kingdom. tel: (0793) 518000 fax: (0793) 518411 gec plessey semiconductors p.o. box 660017 1500 green hills road, scotts valley, ca95067-0017 united states of america. tel (408) 438 2900 fax: (408) 438 5576 customer service centres l france & benelux les ulis cedex tel: (1) 64 46 23 45 tx: 602858f fax : (1) 64 46 06 07 l germany munich tel: (089) 3609 06-0 tx: 523980 fax : (089) 3609 06-55 l italy milan tel: (02) 66040867 fax: (02) 66040993 l japan tokyo tel: (03) 3296-0281 fax: (03) 3296-0228 l north america integrated circuits and microwave products, scotts valley, usa tel: (408) 438 2900 fax: (408) 438 7023. hybrid products, farmingdale, usa tel (516) 293 8686 fax: (516) 293 0061. l south east asia singapore tel: (65) 3827708 fax: (65) 3828872 l sweden stockholm tel: 4687029770 fax: 4686404736 l uk, eire, denmark, finland & norway swindon tel: (0793) 518510 tx: 444410 fax : (0793) 518582 these are supported by agents and distributors in major countries world-wide. gec plessey semiconductors 1993 publication no. ds2039 issue no. 2.1 september 1993 this publication is issued to provide information only which (unless agreed by the company in writing) may not be used, applied or reproduced for any purpose nor form part of any order or contract nor to be regarded as a representation relating to the products or services concerned. no warranty or guarantee express or implied is made regard ing the capability, performance or suitability of any product or service. the company reserves the right to alter without prior knowledge the specification, design or price of any product or service. information concerning possible methods of use is provided as a guide only and does not constitute any guarantee that such methods of use will be satisfactory in a specific piece of equipment. it is the user's responsibility to fully determine the performance and suitability of any equipment using such information and to ensure that any publication or data used is up to date and has not been superseded. these products are not suitable for use in any medical products whose failure to perform may result in significant injury or death to the user. all products and materials are sold and services provided subject to the company's conditions of sale, w hich are available on request. package details dimensions are shown thus: mm (in) 051 (002) min 8 leads at 254 (010) nom. spacing 038/061 (0015/024) 1016 (040) max 8-lead plastic dil C dp8 1 8 305 (0120) min pin 1 ref notch 023/041 (0009/0016) 762 (03) nom ctrs 711 (028) max 508/(020) max this package outline diagram is for guidance only. please contact your gps customer service centre for further information. 114/165 (0045/0107)
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