SL1454

Obsolescence Notice This product is obsolete. This information is available for your convenience only. For more information on Zarlink’s obsolete products and replacement product lists, please visit http://products.zarlink.com/obsolete_products/ THIS DOCUMENT IS FOR MAINTENANCE PURPOSES ONLY AND IS NOT RECOMMENDED FOR NEW DESIGNS ADVANCE INFORMATION 2039-2·1 SL1454 WIDEBAND LINEAR FM DETECTOR FOR SATELLITE TV 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. 0V DEMODULATOR COIL DEMODULATOR COIL 0V 1 2 8 7 INPUT SIGNAL INPUT REF VCC VIDEO OUTPUT SL1454 3 4 6 5 FEATURES s Excellent Threshold s Negligible Differential Gain and Phase Errors s Video Bandwidth Suitable for High Definition TV s High Sensitivity and Wide Dynamic Range s Wide Operating Frequency Range: 70 to 150MHz DP8 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 210°C to180°C 7V 2·5V p-p 255°C to 1150°C 1175°C ORDERING INFORMATION SL1454 NA DP (14-lead plastic DIL package) QUADRATURE DEMODULATOR COMPONENTS 1k 2k 70p 1k INPUT REF INPUT SIGNAL 7 8 2 3 VCC 6 2k 2p 2p 5 VIDEO OUTPUT INPUT AMPLIFIER DEMODULATOR VIDEO AMPLIFIER 1 4 0V 0V Fig. 2 Block diagram SL1454 ELECTRICAL CHARACTERISTICS These characteristics are guaranteed over the following conditions (unless otherwise stated): TAMB = 125°C, VCC = 14·5V to 15·5V, Q = 2, f = 140MHz Characteristic Pin Min. Supply current, ICC Video output voltage Video bandwidth Minimum operating frequency Maximum operating frequency Input voltage Intermodulation 6 5 5 8 8 8 5 Value Typ. 30 0·4 10 70 150 10 250 Max. 35 mA V p-p MHz MHz MHz mVrms dB VCC = 5V Df = 21·4MHz p-p Units Conditions 300 Differential gain Differential phase Signal-to-noise ratio 5 5 5 70 ,61 ,61 % deg dB Product of input modulation: f = 4·4MHz, Df = 21·4MHz p-p and f = 6MHz, Df = 3MHz p-p (PAL colour and sound subcarriers). Df = 21·4MHz p-p. Demodulated staircase referred to input staircase before modulation. Demodulated colour bar waveform referred to waveform before modulation. Ratio of output with Df = 21·4MHz p-p at 1MHz to output rms noise in 10MHz bandwidth with Df = 0. QUADRATURE COIL        2 3 15V 15V 1·75k 5 3·2k 400 400 2mA 1·8k 2·5V 2p 0V 2k 0V 2·5V 2k 640 0V VIDEO OUTPUT 70p 1k 2mA 2p 0V 3mA 0V 1k 8 7 INPUT SIGNAL INPUT REF Fig. 3 Input/output interface circuits 2 SL1454 15V VIDEO OUTPUT 5 6 4 3 40n SL1454 1n 140MHz INPUT 0·1µ 1n 0V 7 8 2 1 82 Q=2 33p Fig. 4 Typical application for 140MHz 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 precaution 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 0.1µF 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= 1 2p=LC 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 = Q2πfL = 2323π3140310630·0431026 = 70·3717Ω Allowing for the internal 800Ω resistance between pins 2 and 3 (see Fig. 3), the external resistance should be 77.1Ω Choose . 82Ω .. For Q = 3 Total R = Q2πfL = 3323π 3140310630·0431026 =105·56Ω Allowing for the internal 800Ω resistance, the external resistance should be 121·5Ω, so choose 120Ω. When using a dual tuned circuit the value of coupling capacitor is dependent of the Q factor. Table 2 gives a guide to the values needed for best linearity. 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 = Q2πfL The internal 800Ω 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 3 SL1454 Q 6 4 2 Bandwidth 10MHz 11MHz 12MHz Q 6 4 3 Coupling capacitor 3·9pF 5·6pF 10pF Table 1 Table 2 Q=6 DC OUTPUT VOLTAGE (V) DC OUTPUT VOLTAGE (V) Q=4 2·5 Q=6 2·5 Q=4 Q=2 Q=2 2·0 2·0 1·5 1·5 0 120 130 140 150 160 0 120 130 140 150 160 FREQUENCY (MHz) FREQUENCY (MHz) (a) Single tuned quadrature network (b) Double tuned quadrature network Fig. 5 Output voltage v. input frequency 15V VIDEO OUTPUT 5 6 4 3 40n 120 10p 40n 33p 120 SL1454 1n 140MHz INPUT 0·1µ 1n 7 8 2 1 33p 10p Q=3 0V Fig. 6 Example of double tuned quadrature circuit 4 SL1454 NOTES 5 SL1454 PACKAGE DETAILS Dimensions are shown thus: mm (in) 1·14/1·65 (0·045/0·107) 1 7·11 (0·28) MAX 8 10·16 (0·40) MAX 5·08/(0·20) MAX PIN 1 REF NOTCH 7·62 (0·3) NOM CTRS 0·23/0·41 (0·009/0·016) 0·51 (0·02) 3·05 (0·120) MIN MIN 0·38/0·61 (0·015/0·24) 8 LEADS AT 2·54 (0·10) NOM. SPACING 8-LEAD PLASTIC DIL – DP8 This package outline diagram is for guidance only. Please contact your GPS Customer Service Centre for further information. 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 q FRANCE & BENELUX Les Ulis Cedex Tel: (1) 64 46 23 45 Tx: 602858F Fax : (1) 64 46 06 07 q GERMANY Munich Tel: (089) 3609 06-0 Tx: 523980 Fax : (089) 3609 06-55 q ITALY Milan Tel: (02) 66040867 Fax: (02) 66040993 q JAPAN Tokyo Tel: (03) 3296-0281 Fax: (03) 3296-0228 q NORTH AMERICA Integrated Circuits and Microwave Products, Scotts Valley, USA Tel: (408) 438 2900 Fax: (408) 438 7023. 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Manufacturing does not necessarily include testing of all functions or parameters. 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 Zarlink’s conditions of sale which are available on request. Purchase of Zarlink’s I2C components conveys a licence under the Philips I2C Patent rights to use these components in and I2C System, provided that the system conforms to the I2C Standard Specification as defined by Philips. Zarlink, ZL and the Zarlink Semiconductor logo are trademarks of Zarlink Semiconductor Inc. Copyright Zarlink Semiconductor Inc. All Rights Reserved. TECHNICAL DOCUMENTATION - NOT FOR RESALE