PHILIPS SA614A handbook
Contents
1. with respect to the Viy 5 p IN If Vin A Sin Ot gt Vo A Sin or gt Rz 201 o 01 Multiplying the two signals in the mixer and low pass filtering yields Vin Vo A2 Sin ot gt Vout A2 Cos 7 _ BON 3 4 20 aa Sin Ot T b after low pass filtering 01 sj 5 4 A sin o 0 04 AO 6 Vout 204 2 ALE 01 Q 0 200 T 2 For Oy lt lt Which is discriminated FM output Note that AG is the deviation frequency from the carrier Ref Krauss Raab Bastian Solid State Radio Eng Wiley 1980 p 311 Example At 455kHz IF with 5kHz FM deviation The maximum normalized frequency will be 455 5kHz NE 1 01 tee 1 010 or 0 990 Go to the f vs normalized frequency curves Figure 12 and draw a vertical straight line at 0 ray 1 01 The curves with Q 100 Q 40 are not linear but Q 20 and less shows better linearity for this application Too small Q decreases the amplitude of the discriminated FM signal Eq 6 gt Choose a Q 20 The internal R of the 614A is 40k From Eq ic and then 1b it results that Cp Cs 174pF and L 0 7mH 1997 Nov 07 10 Product specification SA614A A more exact analysis including the source resistance of the previous stage shows that there is a series and a parallel resonance in the phase detector tank To make the parallel and series resonances close and to get maximum attenua2. Cellular radio FM IF matching network for 12dB SINAD Signal to Noise and Distortion e High performance communications receivers ratio at 455kHz Intermediate frequency amplification and detection up to 25MHz SA614A meets cellular radio specifications a yamp P RF level meter e Spectrum analyzer Instrumentation FSK and ASK data receivers ORDERING INFORMATION DESCRIPTION TEMPERATURE RANGE ORDER CODE DWG 16 Pin Plastic Dual In Line Package DIP 40 to 85 C SA614AN SOT38 4 16 Pin Plastic Small Outline SO package Surface mount 40 to 85 C SA614AD SOT109 1 1997 Nov 07 2 853 0594 18663 Philips Semiconductors Product specification Low power FM IF system SA614A BLOCK DIAGRAM 16 15 14 13 12 11 10 9 SIGNAL STRENGTH SR00324 Figure 2 Block Diagram ABSOLUTE MAXIMUM RATINGS SYMBOL PARAMETER RATING UNITS Storage temperature range 65 to 150 Ta Operating ambient temperature range SA614A 4010485 O to 85 Thermal impedance D package 90 N package 75 C W DC ELECTRICAL CHARACTERISTICS Voc 6V Ta 25 C unless otherwise stated LIMITS SYMBOL PARAMETER TEST CONDITIONS SA614A O 4A UNITS ee E E lec DO current drain pee switch input threshold ON Ore 1997 Nov 07 3 Philips Semiconductors Product specification Low power FM IF system SA614A AC ELECTRICAL CHARACTERISTICS Typical reading at T 25 C Voc
3. The final stability consideration is phase shift The phase shift of the limiters is very low but there is phase shift contribution from the 1997 Nov 07 Product specification SA614A quadrature tank and the filters Most filters demonstrate a large phase shift across their passband especially at the edges If the quadrature detector is tuned to the edge of the filter passband the combined filter and quadrature phase shift can aggravate stability This is not usually a problem but should be kept in mind Quadrature Detector Figure 7 shows an equivalent circuit of the SA614A quadrature detector It is a multiplier cell similar to a mixer stage Instead of mixing two different frequencies it mixes two signals of common frequency but different phase Internal to the device a constant amplitude limited signal is differentially applied to the lower port of the multiplier The same signal is applied single ended to an external capacitor at Pin 9 There is a 90 phase shift across the plates of this capacitor with the phase shifted signal applied to the upper port of the multiplier at Pin 8 A quadrature tank parallel L C network permits frequency selective phase shifting at the IF frequency This quadrature tank must be returned to ground through a DC blocking capacitor The loaded Q of the quadrature tank impacts three fundamental aspects of the detector Distortion maximum modulated peak deviation and audio output amplitude Typ
4. 6V unless otherwise stated IF frequency 455kHz IF level 47dBm FM modulation 1kHz with 8kHz peak deviation Audio output with C message weighted filter and de emphasis capacitor Test circuit Figure 3 The parameters listed below are tested using automatic test equipment to assure consistent electrical characterristics The limits do not represent the ultimate performance limits of the device Use of an optimized RF layout will improve many of the listed parameters LIMITS SYMBOL PARAMETER TEST CONDITIONS SA614A UNITS TYP RSSI output NOTE 1 SA614A data sheets refer to power at 50Q input termination about 21dB less power actually enters the internal 1 5k input SA614A 50 SA614A 1 5k SA615 1 5k 97dBm 118dBm 47dBm 68dBm 3dBm 18dBm The SA615 and SA614A are both derived from the same basic die The SA615 performance plots are directly applicable to the SA614A 1997 Nov 07 4 Philips Semiconductors Low power FM IF system Product specification SA614A ci c2 c3 c4 c5 c6 c7 c8 c9 c10 c c12 F1 F2 R1 R2 R3 R4 Oo NE614A TEST CIRCUIT Ve Q 20 LOADED INPUT a F R1 2 re z 2 C7 a SA614A AR c3 c MUTE INPUT 100nF 80 20 63V K10000 25V Ceramic 100nF 10 50V 100nF 10 50V 100nF 10 50V 100nF 10 50V 10pF 2 100V NPO Ceramic 100nF 10 50V 100nF 10 50V 15
5. ES 6 8uF 4 F 0 1uF SA604A ot 1 2 3 4 2 3 4 5 6 7 8 ka I folie DATA 0 21 jod aie 0 288H 22pF T 100nF a wo EP u 8 J RSSI VOLTS z2z w R fe Pani Run THD NOISE U gt A Q O ous i a Suz OLI AM 80 MOD o m at 22 lt 120 100 80 60 40 20 602 RF INPUT dBm 509 Rn Figure 5 Typical Application Cellular Radio 45MHz to 455kHz CIRCUIT DESCRIPTION The SA614A is a very high gain high frequency device Correct operation is not possible if good RF layout and gain stage practices are not used The SA614A cannot be evaluated independent of circuit components and board layout A physical layout which correlates to the electrical limits is shown in Figure 3 This configuration can be used as the basis for production layout The SA614A is an IF signal processing system suitable for IF frequencies as high as 21 4MHz The device consists of two limiting amplifiers quadrature detector direct audio output muted audio output and signal strength indicator with log output characteristic The sub systems are shown in Figure 4 A typical application with 45MHz input and 455kHz IF is shown in Figure 5 IF Amplifiers The IF amplifier section consists of two log limiting stages The first consists of two differential amplifiers with 39dB of gain and a small signal bandwidth of 41MHz when driven from a 50Q source The output of the first limiter is a low impedance e
6. U RF COMMUNICATIONS PRODUCTS DATA SAEET SA614A Low power FM IF system Product specification Replaces data of December 15 1994 1997 Nov 07 IC17 Data Handbook Philips Semic onductors PHILIPS Philips Semiconductors Product specification MMMM Low power FM IF system SA614A DESCRIPTION PIN CONFIGURATION The SA614A is an improved monolithic low power FM IF system incorporating two limiting intermediate frequency amplifiers quadrature detector muting logarithmic received signal strength D and N Packages indicator and voltage regulator The SA614A features higher IF FAME DECOUPLING AE AN bandwidth 25MHz and temperature compensated RSSI and GND IF AMP DECOUPLING limiters permitting higher performance application compared with the MUTE INPUT IF AMP OUTPUT SA604 The SA614A is available in a 16 lead dual in line plastic ies Gi and 16 lead SO surface mounted miniature package RSSI OUTPUT LIMITER INPUT MUTE AUDIO OUTPUT LIMITER DECOUPLING FEATURES UNMUTE AUDIO OUTPUT LIMITER DECOUPLING Low power consumption 3 3mA typical QUADRATURE INPUT LIMITER e Temperature compensated logarithmic Received Signal Strength Indicator RSSI with a dynamic range in excess of 90dB SR00323 Figure 1 Pin Configuration Two audio outputs muted and unmuted Low external component count suitable for crystal ceramic filters APPLICATIONS Excellent sensitivity 1 5uV across input pins 0 22uV into 50Q
7. derived from the original mm dimensions UNIT Ay A2 A3 c DW e0 HE 0 25 10 0 4 0 6 2 0 19 9 8 3 8 5 8 0 0098 0 39 0 16 0 0075 0 38 0 15 inches Note 1 Plastic or metal protrusions of 0 15 mm maximum per side are not included OUTLINE REFERENCES EUROPEAN VERSION IEC JEDEC EIAJ PROJECTION ISSUE DATE OT109 1 076E07S MS 012AC ETO 91 08 13 95 01 23 1997 Nov 07 13 Philips Semiconductors Product specification Low power FM IF system SA614A DEFINITIONS Data Sheet Identification Product Status Definition This data sheet contains the design target or goal specifications for product development Specifications Objective Specification Formative or in Design i may change in any manner without notice This data sheet contains preliminary data and supplementary data will be published at a later date Philips Preliminary Specification Preproduction Product Semiconductors reserves the right to make changes at any time without notice in order to improve design and supply the best possible product This data sheet contains Final Specifications Philips Semiconductors reserves the rightto make changes Product Specification pul Producton at any time without notice in order to improve design and supply the best possible product Philips Semiconducto
8. don t underestimate the importance of good supply bypass At 455kHz if the layout of Figure 3 or one substantially similar is used it is possible to directly connect ceramic filters to the input and between limiter stages with no special consideration At frequencies above 2MHz some input impedance reduction is usually necessary Figure 9 demonstrates a practical means As illustrated in Figure 10 430Q external resistors are applied in parallel to the internal 1 6kQ load resistors thus presenting approximately 330Q to the filters The input filter is a crystal type for narrowband selectivity The filter is terminated with a tank which transforms to 330Q The interstage filter is a ceramic type which doesn t contribute to system selectivity but does suppress wideband noise and stray signal pickup In wideband 10 7MHz IFs the input filter can also be ceramic directly connected to Pin 16 In some products it may be impractical to utilize shielding but this mechanism may be appropriate to 10 7MHz and 21 4MHz IF One of the benefits of low current is lower radiated field strength but lower does not mean non existent A spectrum analyzer with an active probe will clearly show IF energy with the probe held in the proximity of the second limiter output or quadrature coil No specific recommendations are provided but mechanical shielding should be considered if layout bypass and input impedance reduction do not solve a stubborn instability
9. ical quadrature curves are illustrated in Figure 12 The phase angle translates to a shift in the multiplier output voltage Thus a small deviation gives a large output with a high Q tank However as the deviation from resonance increases the non linearity of the curve increases distortion and with too much deviation the signal will be outside the quadrature region limiting the peak deviation which can be demodulated If the same peak deviation is applied to a lower Q tank the deviation will remain ina region of the curve which is more linear less distortion but creates a smaller phase angle smaller output amplitude Thus the Q of the quadrature tank must be tailored to the design Basic equations and an example for determining Q are shown below This explanation includes first order effects only Frequency Discriminator Design Equations for SA614A VOUT SR00333 Figure 11 c 1a S 1 Vo e eV 2 Cp Cs 01 0 2 1 QS s where 4 1 1b V L Cp Cs Q1 R Cp Cs oy 1c Philips Semiconductors Low power FM IF system From the above equation the phase shift between nodes 1 and 2 or the phase across Cg will be 04 2 d ZVo z NIN tg Q10 01 2 tela Figure 12 is the plot of vs 2 01 It is notable that at 4 the phase shift is gt and the response is close to a straight Ao line with a slope of The signal Vo would have a phase shift of T 20 P
10. iconductors and Philips Electronics North America Corporation for any damages resulting from such improper use or sale Philips Semiconductors Copyright Philips Electronics North America Corporation 1997 811 East Arques Avenue All rights reserved Printed in U S A P O Box 3409 Sunnyvale California 94088 3409 Telephone 800 234 7381 Lett make things beter SLAM 5 PHILIPS Copyright Each Manufacturing Company All Datasheets cannot be modified without permission This datasheet has been download from www AllDataSheet com 100 Free DataSheet Search Site Free Download No Register Fast Search System www AllDataSheet com
11. in Reduction ence Figure 9 Practical Termination i H 430 SR00332 Figure 10 Crystal Input Filter with Ceramic Interstage Filter Because of the very high gain bandwidth and input impedance of the limiters there is a very real potential for instability at IF cause attenuation greater than the gain of the forward path then frequencies above 455kHz The basic phenomenon is shown in oscillation or low level regeneration is likely If regeneration occurs Figure 8 Distributed feedback capacitance inductance and radiated fields forms a divider from the output of the limiters back to the inputs including RF input If this feedback divider does not 1997 Nov 07 two symptoms may be present 1 The RSSI output will be high with no signal input should nominally be 250mV or lower and 2 the demodulated output will demonstrate a threshold Above a certain Philips Semiconductors Low power FM IF system input level the limited signal will begin to dominate the regeneration and the demodulator will begin to operate in a normal manner There are three primary ways to deal with regeneration 1 Minimize the feedback by gain stage isolation 2 lower the stage input impedances thus increasing the feedback attenuation factor and 3 reduce the gain Gain reduction can effectively be accomplished by adding a
12. kQ resistor the output characteristic is 0 5V for a 10dB change in the input amplitude Additional Circuitry Internal to the SA614A are voltage and current regulators which have been temperature compensated to maintain the performance of the device over a wide temperature range These regulators are not accessible to the user 200 175 150 125 100 75 50 25 0 0 95 0 975 1 0 1 025 1 05 SR00334 Aw 1997 Nov 07 Philips Semiconductors Product specification Low power FM IF system SA614A DIP16 plastic dual in line package 16 leads 300 mil SOT38 4 seating plane 5 scale DIMENSIONS inch dimensions are derived from the original mm dimensions A Ay Ao max min max UNIT b by ba c pM EV 1 73 0 53 1 25 0 36 19 50 6 48 10 0 1 30 0 38 0 85 0 23 18 55 6 20 8 3 0 068 0 021 0 049 0 014 0 77 0 26 0 39 inches oa 0 051 0 015 0 033 0 009 0 73 o24 0 33 501 0 254 Note 1 Plastic or metal protrusions of 0 25 mm maximum per side are not included OUTLINE REFERENCES EUROPEAN VERSION JEDEC EIAJ PROJECTION 92 14 44 SOT38 4 E 95 01 14 ISSUE DATE 1997 Nov 07 12 Philips Semiconductors Product specification Low power FM IF system SA614A S016 plastic small outline package 16 leads body width 3 9 mm SOT109 1 scale DIMENSIONS inch dimensions are
13. mitter follower with 1kQ of equivalent series resistance The second limiting stage consists of three differential amplifiers with a gain of 62dB and a 1997 Nov 07 small signal AC bandwidth of 28MHz The outputs of the final differential stage are buffered to the internal quadrature detector One of the outputs is available at Pin 9 to drive an external quadrature capacitor and L C quadrature tank Both of the limiting amplifier stages are DC biased using feedback The buffered output of the final differential amplifier is fed back to the input through 42kQ resistors As shown in Figure 4 the input impedance is established for each stage by tapping one of the feedback resistors 1 6kQ from the input This requires one additional decoupling capacitor from the tap point to ground 42k V 15 16 70014 31 6k 7k 1 T 40k 7 SR00328 Figure 6 First Limiter Bias Philips Semiconductors Product specification Low power FM IF system SA614A 42k 9 11 Va 12 40k 8 10 d 40k 80k 4 L SR00329 SR00330 Figure 7 Second Limiter and Quadrature Detector Figure 8 Feedback Paths HIGH IMPEDANCE HIGH IMPEDANCE LOW IMPEDANCE a Terminating High Impedance Filters with Transformation to Low Impedance t RESISTIVE LOSS INTO BPF x b Low Impedance Termination and Ga
14. nF 10 50V 150pF 2 100V N1500 Ceramic 1nF 10 100V K2000 Y5P Ceramic 6 8uF 20 25V Tantalum 455kHz Ceramic Filter Murata SFG455A3 455kHz Ce 180pF TOKO RMC 2A6597H 510 1 1 4W Metal Film 15009 1 1 4W Metal Film 15000 5 1 8W Carbon Composition 100kQ 1 1 4W Metal Film SIGNETICS NE614 TEST CKT LTL ik o ano 00 O micz o OKO Bs n 2 viva OIGNV O AUDIO O DATA OUTPUT OUTPUT RSSI OUTPUT SIGNETICS NE614 TEST CKT GO SR00325 1997 Nov 07 Figure 3 SA614A Test Circuit Philips Semiconductors Product specification Low power FM IF system SA614A GND 42k l 42k 1 6k 1 6k VOLTAGE CURRENT CONVERTER Vec SR00326 Figure 4 Equivalent Circuit 1997 Nov 07 Philips Semiconductors Low power FM IF system Product specification SA614A Ju SFG455A3 1 22pF mAN NE604A TEST CIRCUIT 0 1pF nn Dg T j 455kHz gt i 44 545 Tt ai 5 5uH 3rd OVERTURE 5 6pF XTAL 0 1uF m SFG455A3 10pF L 6V EPE
15. plications Figure 5 the optimum linearity was achieved with a 5 1kQ resistor from the output of the first limiter Pin 14 to the input of the interstage filter With this resistor from Pin 14 to the filter sensitivity of 0 25UV for 12dB SINAD was achieved With the 3 6kQ resistor sensitivity was Philips Semiconductors Low power FM IF system optimized at 0 22UV for 12dB SINAD with minor change in the RSSI linearity Any application which requires optimized RSSI linearity such as spectrum analyzers cellular radio and certain types of telemetry will require careful attention to limiter interstage component selection This will be especially true with high IF frequencies which require insertion loss or impedance reduction for stability At low frequencies the RSSI makes an excellent logarithmic AC voltmeter For data applications the RSSI is effective as an amplitude shift keyed ASK data slicer If a comparator is applied to the RSSI and the threshold set slightly above the no signal level when an in band signal is received the comparator will be sliced Unlike FSK Product specification SA614A demodulation the maximum data rate is somewhat limited An internal capacitor limits the RSSI frequency response to about 100kHz At high data rates the rise and fall times will not be symmetrical The RSSI output is a current to voltage converter similar to the audio outputs However an external resistor is required With a 91
16. rator Once the threshold of the reference frequency or no signal condition has been established the two outputs will shift in opposite directions higher or lower output voltage as the input frequency shifts The output of the comparator will be logic output The choice of op amp or comparator will depend on the data rate With high IF frequency 10MHz and above and wide IF bandwidth L C filters data rates in excess of 4Mbaud are possible RSSI The received signal strength indicator or RSSI of the SA614A demonstrates monotonic logarithmic output over a range of 90dB The signal strength output is derived from the summed stage currents in the limiting amplifiers It is essentially independent of the IF frequency Thus unfiltered signals at the limiter inputs spurious products or regenerated signals will manifest themselves as RSSI outputs An RSSI output of greater than 250mV with no signal or a very small signal applied is an indication of possible regeneration or oscillation In order to achieve optimum RSSI linearity there must be a 12dB insertion loss between the first and second limiting amplifiers With a typical 455kHz ceramic filter there is a nominal 4dB insertion loss in the filter An additional 6dB is lost in the interface between the filter and the input of the second limiter A small amount of additional loss must be introduced with a typical ceramic filter In the test circuit used for cellular radio ap
17. rs and Philips Electronics North America Corporation reserve the right to make changes without notice in the products including circuits standard cells and or software described or contained herein in order to improve design and or performance Philips Semiconductors assumes no responsibility or liability for the use of any of these products conveys no license or title under any patent copyright or mask work right to these products and makes no representations or warranties that these products are free from patent copyright or mask work right infringement unless otherwise specified Applications that are described herein for any of these products are for illustrative purposes only Philips Semiconductors makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification LIFE SUPPORT APPLICATIONS Philips Semiconductors and Philips Electronics North America Corporation Products are not designed for use in life support appliances devices or systems where malfunction of a Philips Semiconductors and Philips Electronics North America Corporation Product can reasonably be expected to result in a personal injury Philips Semiconductors and Philips Electronics North America Corporation customers using or selling Philips Semiconductors and Philips Electronics North America Corporation Products for use in such applications do so at their own risk and agree to fully indemnify Philips Sem
18. tion of higher harmonics at 455kHz IF we have found that a Cs 10pF and Cp 164pF commercial values of 150pF or 180pF may be practical will give the best results A variable inductor which can be adjusted around 0 7mH should be chosen and optimized for minimum distortion For 10 7MHz a value of Cs 1pF is recommended Audio Outputs Two audio outputs are provided Both are PNP current to voltage converters with 55kQ nominal internal loads The unmuted output is always active to permit the use of signaling tones in systems such as cellular radio The other output can be muted with 7OdB typical attenuation The two outputs have an internal 180 phase difference The nominal frequency response of the audio outputs is 300kHz this response can be increased with the addition of external resistors from the output pins to ground in parallel with the internal 55k resistors thus lowering the output time constant Singe the output structure is a current to voltage converter current is driven into the resistance creating a voltage drop adding external parallel resistance also has the effect of lowering the output audio amplitude and DC level This technique of audio bandwidth expansion can be effective in many applications such as SCA receivers and data transceivers Because the two outputs have a 180 phase relationship FSK demodulation can be accomplished by applying the two output differentially across the inputs of an op amp or compa
19. ttenuation between stages This can also lower the input impedance if well planned Examples of impedance gain adjustment are shown in Figure 9 Reduced gain will result in reduced limiting sensitivity A feature of the SA614A IF amplifiers which is not specified is low phase shift The SA614A is fabricated with a 10GHz process with very small collector capacitance It is advantageous in some applications that the phase shift changes only a few degrees over a wide range of signal input amplitudes Stability Considerations The high gain and bandwidth of the SA614A in combination with its very low currents permit circuit implementation with superior performance However stability must be maintained and to do that every possible feedback mechanism must be addressed These mechanisms are 1 Supply lines and ground 2 stray layout inductances and capacitances 3 radiated fields and 4 phase shift As the system IF increases so must the attention to fields and strays However ground and supply loops cannot be overlooked especially at lower frequencies Even at 455kHz using the test layout in Figure 3 instability will occur if the supply line is not decoupled with two high quality RF capacitors a 0 1uF monolithic right at the Vcc pin and a 6 8uF tantalum on the supply line An electrolytic is not an adequate substitute At 10 7MHz a 1uF tantalum has proven acceptable with this layout Every layout must be evaluated on its own merit but
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PHILIPS SA614A handbook