TDA1072A AM RECEIVER CIRCUIT GENERAL DESCRIPTION The TDA1072A integrated AM receiver circuit performs the active and part of the filtering functions of an AM radio receiver. !t is intended for use in mains-fed home receivers and car radios. The circuit can be used for oscillator frequencies up to 50 MHz and can handle r.f. signals up to 500 mV. R.F. radiation and sensitivity to interference are minimized by an almost symmetrical design. The voltage- controlled oscillator provides signals with extremely low distortion and high spectral purity over the whole frequency range even when tuning with variable capacitance diodes. If required, band switching diodes can easily be applied. Selectivity is obtained using a block filter before the i.f. amplifier. Features @ Inputs protected against damage by static discharge Gain-controlled r.f. stage Double balanced mixer Separately buffered, voltage-controlled and temperature-compensated oscillator, designed for simple coils Gain-controlled i.f. stage with wide a.g.c. range Full-wave, balanced envelope detector Internal generation of a.g.c. voltage with possibility of second-order filtering Buffered field strength indicator driver with short-circuit protection A.F. preamplifier with possibilities for simple a.f. filtering Electronic standby switch QUICK REFERENCE DATA Supply voltage range Vp 7,5to 18 V Supply current range Ip 15 to 30 mA R.F. input voltage for S + N/N = 6 dB at m = 30% Vi typ. 1,5 pV R.F. input voltage for 3% total harmonic distortion (THD) at m = 80% Vi typ. 500 mV A.F. output voltage with Vj = 2 mV; f; = 1 MHz; m = 30% and fr, = 400 Hz Vo(af} typ. 310 mV A.G.C. range: change of Vj for 1 dB change of Vo(af) typ. 86 dB Field strength indicator voltage at Vj = 500 mV; Ri (g) = 2,7 kQ VIND typ. 2,8 V PACKAGE OUTLINE 16-lead DIL; plastic (SOT38). May 1984 605TDA1072A | | Cose Yi 12 to 440 pF OtuF. c optional ro band switching y cs diodes c 2 to 22 pF, C7 33 an a f 502 4 33 pF .c8 ! Rg = 502 BY 1} R, (10) ue - _ L +-O--y> R2 Tes 22kQ 222 47 uF Ry {9) z + ~ 95 LL 2,7 kQ c c2 1 R3 Lose * 95uH cot Vino 4 s00 rk 100nF 7] L vp 222 1OnF 4 -! 16 15 y 14 13 12 1 10 002 |? 1 25Q 1702 AIN Vv connor LED ale CONTROLLED 3 INDICATOR R.F. STAGE <4 VOLTAGES OSCILLATOR DRIVER L yv, (a.g.c.) y J V1 V2 V3 4 + v > > try l DOUBLE > GAIN - BALANCED AF. BALANCED eH Sowirens CONTROLLED }j FULL-wave Le4 prRE- be AMPLINER MIXER iF. AMPLIFIER DETECTOR AMPLIFIER L_4. Vp (age) Vp (a.g.c.) -__< k TDA1072A aKa v2 a5ka)) oH 1 2 3 4 5 6 7 8 = al aad eal C16 c17 +c12 cto oo I ! 2,2 uF 22 uF ' ) 22ka | C11 amdyem | 7 [2200F SOE as i JL 7 7 LF. FILTER + Vp (pin 13) N y standby switch Ry =1 3.3nr UL) 12k2 c14 C15 100 nF geo ---L Vo lat MQ 7287714 (1} Coil data: TOKO sample no. 7XNS-A7523DY; L1 : N1/N2 = 12/32; Q, = 65; Op = 57, Filter data: Zp = 700 2 at R3.4 = 3kQ; Z) = 4,8kQ. Fig. 1 Block diagram and test circuit (connections shown in broken lines are not part of the test circuit). 606 May 1984AM receiver circuit TDA1072A FUNCTIONAL DESCRIPTION Gain-controlled r.f. stage and mixer The differential amplifier in the r.f. stage employs an a.g.c. negative feedback network to provide a wide dynamic range. Very good cross-modulation behaviour is achieved by a.g.c. delays at the various signal stages. Large signals are handled with low distortion and the S/N ratio of small! signals is improved. Low noise working is achieved in the differential amplifier by using transistors with low base resistance. A double balanced mixer provides the i.f. output signal to pin 1. Oscillator The differential amplifier oscillator is temperature compensated and is suitable for simple coil connect- ion, The oscillator is voltage-controiled and has little distortion or spurious radiation. It is specially suitable for electronic tuning using variable capacitance diodes. Band switching diodes can easily be applied using the stabilized voltage V11.16. An extra buffered oscillator output (pin 10) is available for driving a synthesizer. If this is not needed, resistor R10) can be omitted. Gain-controlled i.f. amplifier This amplifier comprises two cascaded, variable-gain differential amplifier stages coupled by a band-pass filter. Both stages are gain-controlled by the a.g.c. negative feedback network. Detector The full-wave, balanced envelope detector has very low distortion over a wide dynamic range. Residual i.f. carrier is blocked from the signal path by an internal low-pass filter. A.F. preamplifier This stage preamplifies the audio frequency output signal. The amplifier output has an emitter follower with a series resistor which, together with an external capacitor, yields the required low-pass for a.f. filtering. A.G.C. amplifier The a.g.c. amplifier provides a control voltage which is proportional to the carrier amplitude. Second- order filtering of the a.g.c. voltage achieves signals with very little distortion, even at low audio frequencies. This method of filtering also gives fast a.g.c. settling time which is advantageous for electronic search tuning. The a.g.c. settling time can be further reduced by using capacitors of smailer value in the external filter (C16 and C17). The a.g.c. voltage is fed to the r.f. and i.f. stages via suitable a.g.c. delays. The capacitor at pin 7 can be omitted for low-cost applications. Field strength indicator output A buffered voltage source provides a high-level field strength output signal which has good linearity for logarithmic input signals over the whole dynamic range. If the field strength information is not needed, R__(g) can be omitted. Standby switch This switch is primarily intended for AM/FM band switchirg. During standby mode the oscillator, mixer and a.f. preamplifier are switched off. Short-circuit protection All pins have short-circuit protection to ground. May 1984 607TDA1072A RATINGS Limiting values in accordance with the Absolute Maximum Rating System (IEC 134) Supply voltage Vp=V13-16 max. 20 V Total power dissipation Prot max. 875 mW Input voltage IV14-15| max. 12 Vv V14-16 -V15-16 max. 0,6 V V14-16. V15-16 max. Vp Vv Input current qal, Ilys! max. 200 mA Operating ambient temperature range Tamb 40 to +80 C Storage temperature range Tstg 55 to +150 C Junction temperature Tj max. +125 C THERMAL RESISTANCE From junction to ambient Rth j-a = 80 K/W DEVICE CHARACTERISTICS Vp = V13-16 = 8,5 V; Tamb = 25 OC; fj) = 1 MHz; fry = 400 Hz; m = 30%; fj = 460 kHz; measured in test circuit of Fig. 1; unless otherwise specified parameter symbol min. | typ. | max. | unit Supplies Supply voltage Vp=V13-16 7,5 8,5 18 Vv Supply current Ip=113 15 23 30 mA R.F. stage and mixer Input voitage (d.c. value) V14-16 V15-16 |- Vp/2 | - Vv R.F. input impedance at Vj < 300 nV R14-16 R15-16 | 5,5 - kQ C14-16, C15-16 | 25 | - pF R.F. input impedance at Vj; > 10 mV R14.16, 215-16 | - 8 kQ C14-16, C15-16 | 220 | - pF |.F. output impedance R1-16 500 - - kQ C1-16 - 6 - pF Conversion transconductance before start of a.g.c. I4/Vj - 6,5 - mA/V Maximum i.f. output voltage, inductive coupling to pin 1 V1-13(p-p) - 5 - Vv D.C. value of output current (pin 1) at Vj =OV \4 1,2 _ mA A.G.C. range of input stage = 30 = dB R.F. signal handling capability: input voltage for THD = 3% at m = 80% Vi(rms) - 500 | mV 608 May 1984AM receiver circuit TDA1072A parameter symbol min. |typ. | max. | unit Oscillator Frequency range fose 0,6 - 60 MHz Oscillator amplitude (pins 11 to 12) V41-12 - 130 (150 |jmvV External load impedance R12-114 (ext) 05 |- 200) | kQ2 External load impedance for no oscillation R12-11{ext) ~- - 60 2 Ripple rejection at Vp(rms) = 100 mV; fp = 100 Hz (RR = 20 log[V73.16/V 11-16!) RR - 55 - dB Source voltage for switching diodes (6 x Vee) | V11-16 - 4,2 - Vv D.C. output current (for switching diodes) l14 0 20 mA Change of output voltage at Al41 = 20 mA (switch to maximum load) AV 11-16 - 0,5 - Vv Buffered oscillator output D.C. output voltage V10-16 - 07 |- Vv Output signal amplitude V10-16{p-p) - 320 | - mV Output impedance R10 - 170 j- 2 Output current 110(peak) - - 3 mA |.F., a.g.c. and a.f. stages D.C. input voltage V3-16, V4-16 - 2,0 j- Vv |.F. input impedance R34 2,4 3 3,9 kQ C34 - 7 - pF |.F. input voltage for THD = 3% at m = 80% V3-4 - 90 - mV Voltage gain before start of a.g.c. V3.4/V6-16 - 68 - dB A.G.C. range of i.f. stages: change of V3.4 for 1 dB change of Vo(af): V3-4(ref) = 75 mV AV3.4 - 55 _ dB A.F, output voltage at V3.4(jf) = 50 uV Vo(af) - 130 j- mV A.F. output voltage at V3_4(jf) = 1 mV Volaf) ~ 310 j- mV A.F. output impedance (pin 6) IZo| - 3,5 _ kQd Indicator driver Output voltage at Vj = 0 mV; Rig) = 2,7 kQ V9.16 - 20 150 |mvV Output voltage at V; = 500 mV; Rig) = 2,7 kQ V9.16 2,5 2,8 3,1 Vv Load resistance Rig) 15 |- - kQ May 1984 609TDA1072A DEVICE CHARACTERISTICS (continued) parameter symbol min. { typ. | max. | unit Standby switch Switching threshold at Vp = 7,5 to 18 V; Tamb = 40 to + 80 C on-voltage V2.16 0 - 2,0 Vv off-voltage V2.16 3,5 |- 20 Vv on-current at V9.4g=O0V lg _ - 200 | uA off-current at Vo.41g = 20V Hol - - 10 LA OPERATING CHARACTERISTICS Vp =8,5 V; fj] = 1 MHz; m = 30%; fry = 400 Hz; Tamb = 25 OC; measured in Fig. 1; unless otherwise specified parameter symbol min. | typ. | max. | unit R.F. sensitivity R.F. input required for S + N/N =6 dB Vj - 1,5 uv R.F. input required for S + N/N = 26 dB Vi - 15 - BV R.F. input required for S + N/N = 46 dB Vi - 150 - BV R.F. input at start of a.g.c. Vi = 30 - BV R.F. large signal handling R.F. input at THD = 3%; m = 80% Vj - 500 | - mV R.F. input at THD = 3%; m = 30% Vj - 700 | - mV R.F. input at THD = 10%; m = 30% Vi _ 900 | mV A.G.C. range Change of V; for 1 dB change of Vo(af): Vi(ref) = 500 mV AV} - 86 - dB Change of Vj; for 6 dB change of Vo(af); Vi(ref) = 500 mV AV; - 91 - dB Output signal A.F. output voltage at Vi =4 nV; m = 80% Volaf) - 130 | - mV A.F. output voltage at Vj = 1 mV Vo(af) 240 | 310 |390 | mV THD at Vj = 1 mV; m = 80% dtot - 0,5 - % THD at Vj = 500 mV; m= 30% dtot - 1 - % Signal-to-noise ratio at V; = 100 mV (S +N)/N - 58 _ dB Ripple rejection at Vj = 2 mV; VP(rms) = 100 mV; fp = 100 Hz (RR = 20 log [Vp/Vog(aty}) RR - 38 _ dB 610 May oo | (| TDA1072A AM receiver circuit | parameter symbol min typ. max. {unit Unwanted signals Suppression of i.f. whistles at Vj = 15 pV; m = 0% related to a.f. signal of m = 30% at fj = 2 x fig 2 if 37 - dB at fj > 3 x fig a3 if - 44 - dB I.F. suppression at r.f. input for symmetrical input QF - 40 - dB for asymmetrical input Qt _ 40 _ dB Residual oscillator signal at mixer output at fose 14 (osc) - 1 - BA at 2 X fose 14(20sc) 1,1 - BA APPLICATION INFORMATION 100 nF I 27MH2 tap 1) 33 pF {| 41 G 2202 1,2 wH g (2) (1) Capacitor values depend on crystal type. TDA1072A 7287701 (2) Coil data: 9 windings of 0,1 mm dia laminated Cu wire on TOKO coil set 7K 199CN; Qo = 80. Fig. 2 Oscillator circuit using quartz crystal; centre frequency = 27 MHz. May 1984 611TDA1072A APPLICATION INFORMATION (continued) Vo (at) (dBV) 20 -40 ~60 0 20 40 60 80 100 120 V; (dB xV) Fig. 3 A.F. output as a function of r.f. input in the circuit of Fig. 1; fj = 1 MHz; fp, = 400 Hz; m = 30%. THD (%) C7467 2.2uF 0,1 10 20 100 200 S+N = THD N (%) (dB) 60 6 40 4 20 2 THD 0 Q 0 20 40 60 80 100 120 Vj, (dB uv) Fig. 4 Total harmonic distortion and (S + N}/N as functions of r.f. input in the circuit of Fig. 1; m = 30% for (S + N)/N curve and m = 80% for THD curve. 7287704 1000 2000 fry (Hz) Fig. 5 Total harmonic distortion as a function of modulation frequency at Vj = 5 mV; m = 80%; measured in the circuit of Fig. 1 with C7.16lext) =O uF and 2,2 uF. 612 May 1984AM receiver circuit TDA1072A 7287705 7287706 3 Vo (af) (dB) VIND 0 (Vv) - SRS, 2 10 SAN 1 NJ \ i. 20 I N \ iN 1 ~30 Th N 40 0 50 0 20 40 60 80 100 120 0,1 1 fm (kHz) 10 V; {dB nV) Fig. 6 Indicator driver voltage as a function Fig. 7 Typical frequency response curves from of r.f. input in the circuit of Fig. 1. Fig. 1 showing the effect of filtering as follows: __ with if. filter; -:-:---: withaf, filter; ----- withi.f. and a.f. filters. pe ee _ eee e 7 Roen Vet | 569 15PF Vee L2 502 | | 4,2nF | 7% ||502 6OpF | | 390pF = It (/ | (f (f ' ' _ 6OpF [AERIAL (=140B) Vp a x | VW 16 15 14 13~~CW 1 TDA1072A 7287707 Fig. 8 Car radio application with inductive tuning. 7287708 Vo taf) S+N (m= 30%) (d8V) 20 40 60 0 20 40 60 80 100 V, (dB nV) 120 Fig. 9 A.F. output as a function of r.f. input using the circuit of Fig. 8 with that of Fig. 1. May 1984 613TDA1072A APPLICATION INFORMATION (continued) 0 20 VeFu (dB uV) 120 100 80 0 10 20 30 40 V'aew (9BeV) 7287709 V'aeu (dB pV) 106 86 66 50 60 70 Vet (dB uv) Fig. 10 Suppression of cross-modulation as a function of input signal, measured in the circuit of Fig. 8 with the input circuit as shown in Fig. 11. Curve is for Wanted Vo(af)/Unwanted Vo(af) = 20 dB; Vrtw Vrfy are signals at the aerial input, V sew, V'aey are signals at the unloaded output of the aerial, Wanted signal (Vgey, Vrfyw): fj = 1 MHz; fp, = 400 Hz; m = 30%, Unwanted signal (Vaey, Vrfy): fj = 900 kHz; fp, = 400 Hz; m = 30%. Effective selectivity of input tuned circuit = 21 dB. a _oes POWER ' SPLITTER | ' a Vitw v aew Vwanted + 3 Vifu ' AERIAL V'aeu to radio poi _ 50 | (Fig. 8) input circuit 7 | | Fig. 11 Input circuit to show ! cross-modulation suppression J . Vunwanted (see Fig. 10). 7287710 7287711 120 V42 (rms) (mv) 100 80 60 40 20 Fig. 12 Oscillator amplitude as a function of pin 11, 12 impedance 0 in the circuit of Fig. 8. 0,1 1 10 100 200 2012-11] (k2) & 614 May 1984AM receiving circuit TDA1072A 7287712 THD (%) 0 0 20 40 60 80 100 v,(gBuv) 120 Fig. 13 Total harmonic distortion and (S +N)/N as functions of r.f. input using the circuit of Fig. 8 with that of Fig. 1. 7287713 E= 2t(ref) 40 1,2 80 100 -10 -1 +01 1 10 atig (kHe) 100 Fig. 14 Forward transfer impedance as a function of intermediate frequency for filters 1 to 4 shown in Fig. 15; centre frequency = 455 kHz. May 1984 615TDA1072A APPLICATION INFORMATION (continued) FILTER 1 cy FILTER 3 1,2kQ2 3 SFZ455A Vala 3kQ ' 4 56 pF Ld Lid 3 SFZ455A Vala Ka | 4 3kQ 100 pF 100 pF vores Oe titel Lol N2 SFT455B LaW 7287715 Fig. 15 1.F. filter variants applied to the circuit of Fig. 1. For filter data, refer to Table 1. 616 May 1984| TDA1072A AM receiver circuit Buipuim Jaqno ayt ZN Buipuim sauu! ayy sAempe SI LN Bulpulm e yo Buruulbag ayz sazedipul Mosse Ue YO Buluuibaq ay ap pl 99 8g 9 ZHAL?S ap v9 vg 6b zg ZHABLS ap a 9 ie Se ZH 16s ZH 0'v gE ge 9' (ap ) ylpimpueg wy 89'0 890 9'0 oz'0 dz gg (Z1) BL (11) 29 Ov 4g 40 wD 87 cv 8' 8'r Iz b3ep 493]14 ap se ve vz vz ZH 6s ZH Gv ev vv zp | (dP -) yipimpueg ow Ty Sy ap 9 v v v (anjea yea1dAy) accrl4s vacrzs WSSrz4s VSGbZ4S adA} eveuny| si0}euosay ACGLSLY-SNXL HIVLZSLV-SNXZ | AC8LSZV-SNXZ 9Lg0900V-Sad/1 | ACEZSLV-SNXZ OU 4aPJO OFOL (ZN) (LN) e e e e e e Lege e e e sBurpuim Le -) 6z 5 6z Le ) Gu a) (a zee ) (a 40 e e e e e e e e e JEBW3Y9S SL 09 SL os ('dA1) g9 0 wu 60'0 380'0 600 80'0 60'0 aJIM pazeulwe| nd }o sajaweiq Le: L 6Z : 62 LE: SL (99+ ): 1 ze: ZL ZN :LN ad o06e O0L o06e Of o06e 2 jo anen 1 Zz L7 Ta 1 eJep [109 yun v Z L "OU 483 |1y pL Bly osje aag (ZH SGb = OF Aduanba.s} a4juad 18 aAIND A}IAI}99/8S wunuiido) WnNWwIxeul = AZ si quawysnipe 40y wna Gy, B14 ul UMOYs S4azfI} 4"| 40} B12. | B1GeL 617 , ( 1984TDA1072A APPLICATION INFORMATION (continued) 7287718 standby VB fose switch Fig. 16 Printed-circuit board component side, showing component layout. For circuit diagram see Fig. 1. 7287717 Fig. 17 Printed-circuit board showing track side, * 618 May 1984TDA1072A iver circul AM rece! Buljpuey jeubis-abie; poob 40} pasiuindo o'6e abeys-aid sapnjoul yiNd419 ay, BulYyoUMs M\1/MIA 91U04298)8 pue Bulun} apotp aalyoedes yyIM UOseoIdde olpei seg gy BIG "| Bly 0} sajau e1ep [109 puke sa21y 'y1 104 (Z) ZL LG Sapolp aaiioedes jo dnoi6 pajsajas ay} UO puadap ssopoedes yo sanjeA (1) O1Lf8Z2L 4 46 4 youms Aqpuels dues Aut vy TORN UAZL da We we 4 voovz4s sUG'E T L 4996 UATZ 4922 jv au : {| {t- }}- woo Tr @ 9 G b gf (2) 4 Z v7colval soos Fev 4 6 OL tL Ze et pl St oF i wAL 4 4 aolrss L Li. 4 w#OOL BALT oor 001 4d 3 40 >be N 8rsoa az oot] GNI, , : , DAL HAZ d 280, U oot t N 8vsog BAT eh 4 ae 4 4d97 1 soot. Adgz * 7 00L >= , 4 (yT T ary ca tl 1G) Gay rap * UD g ziLaa zLLaa f gpsoa 98738 dU 001 5 24 OOL 9s 02 =D sd068== gk F * HALE T 90b24 []oxo zz 4d zLiaa 9% BAO0OL +_ P+ NIL, 619 (w 1984