TCA 440 / T Edition 12/95

Transcription

1 Technical Data Edition 12/95 AM - Receiver Circuit Description This is an efficient bipolar monolithic circuit to apply in battery - powered or mains - operated radio receivers up to 3 MHz. It contains controlled RF stage, mixer, separated oscillator and regulated multistage IF amplifier. Features symmetrical structured circuitry controlled RF prestage multiplicative balanced mixer, separated oscillator very well implemented large - signal characteristic begins already from 4.5 V supply voltage terminals for indicating instrument controlled IF amplifier implementing db control range external demodulator (diode wide range of supply voltage between 4.5 and 15 V Package TCA 44 DIP ± ± M /95 1

2 TCA 44 T SOP ± ± ± ± M Pin configuration 1 RF prestage, input 1 9 input IF control amplifier 2 RF prestage, input 2 1 indicator output IF control amplifier 3 RF control amplifier input 11 IF blocking 4 oscillator circuit pin 1 12 input lf amplifier 5 oscillator circuit pin 2 13 IF blocking oscillator circuit pin 3 14 supply voltage 7 IF output 15 mixer output 1 8 ground 1 mixer output 2 Block diagram IF REQUIRED STABILISATION 3. HF - CIRCUIT 1 2 PRE- STAGE MIXER 1 st IF STAGE 2 nd IF STAGE 3 rd IF STAGE 4 th IF STAGE 7 AF 5 4 OSCILLATOR IF GAIN CONTROL IF FILTER TUNING INDICATOR 2 12/95

3 Functional description It contains several function units, which enable designing and assembling of efficient AM tuners. Caused by internal voltage stabilization characteristics are rather independent from supply voltage. The RF input signal reaches via a controllable and overdriving proof preselector stage a balanced mixer. By means of a RF - signal generated by a separated oscillator the input signal is transported into IF. Multiplicative mixing causes only few harmonic content. Gain control is carried out by means of two separated feedback control loops for preselector stage and IF amplifier. By these a loop bandwidth of approximately 1 db is obtained. The control voltage of the IF - amplifier can be used to drive a moving - coil instrument (field strength indicator. The IF amplifier consists of 4 amplifier stages, the first, second and third can be controlled. The bandwidth of the IF amplifier is approximately 2 MHz and on that account sufficient for usual IF frequencies in the AM range of approximately 4 khz. The symmetrical arrangement of the entire circuitry guarantees well oscillating. The bridge of the mixer avoids direct breakdown. Absolute maximum ratings min max unit Supply voltage V Junction temperature T j 15 C Ambient operating temperature T a C Storage temperature T s C Total thermal resistance R thja 12 K/W Recommended operational conditions min max unit Supply voltage V Ambient operating temperature T a -1 7 C 12/95 3

4 Characteristics refer to application examples, f i = 1 MHz, f osc = khz, f lf = 455 khz, = 9 V, f m = 1 khz, m =.8, voltages refer to ground, T a = 2 to 25 C, unless specified otherwise min typ max unit Current and voltage supply (no RF signal Supply voltage V V Current consumption V 14-8 = 4.5 V I 14 7 ma V 14-8 = 9 V I ma V 14-8 = 15 V I ma Entire receiver RF level variation with V NF = db V RF 5 db with V NF = 1 db V RF 8 db NF output voltages (symmetrically measured at 1-2 V ihf = 2 µv, m =.8 V NF(rms 14 mv V ihf = 1 mv, m =.8 V NF(rms 2 mv V ihf = 5 mv, m =.8 V NF(rms mv V ihf = 2 µv, m =.3 V NF(rms 5 mv V ihf = 1 mv, m =.3 V NF(rms 1 mv V ihf = 5 mv, m =.3 V NF(rms 13 mv RF input sensitivity measured at Ω, m =.3, R G = 54 Ω signal-to-noise ratio S + N/N = db V irf 1 µv S + N/N = 2 db V irf 7 µv S + N/N = 58 db V irf 1 mv Maximum RF input voltage V ihf 1.5 V (THD = 1 % Total harmonic distortion V HF = 5 mv THD % V HF = 3 mv THD % RF part Input frequency range f ihf 5 MHz Output frequency f F = f osc -f ihf f IF 455 khz Control range G V 38 db 4 12/95

5 min typ max unit IF suppression a lf 2 db between 1-2 and 15 RF input impedance unbalanced coupling V ihfmax Z i 2 II 5 kωiipf V ihfmin Z i 2.2 II 1.5 kωiipf balanced coupling V ihfmax Z i 4.5 kω V ihfmin Z i 4.5 II 1.5 kωiipf Mixer output impedance (pin 15 or 1 Z o 25 II 4.5 kωiipf Steepness S HF 28 ms IF part Input frequency range f ilf 2 MHz Control range G V 2 db f ilf = 455 khz, V NF = 1 db Start of control V ctrlf 14 µv ( V iif / V NF = 1 db / 3 db maximum IF input voltage V ilfmax 2 mv (THD NF = 1 % NF output voltage applied to Ω V ZF = 3 µv V NF(rms 5 mv V ZF = 3 mv V NF(rms 2 mv V ZF = 3 mv; m =.3 V NF(rms 7 mv IF input impedance (unbanlanced coupling Z ilf 3 II 3 kωllpf IF output impedance Z O 2 II 8 kωiipf (pin 7 Indication instrument Recommended indication instruments: 5 µa (R i = 8 Ω 3 µa (R i = 1.5 kω For indication a voltage source of m V (EMF and an internal source impedance of 4 Ω is available. 12/95 5

6 Dependences S ( ms 4 S = f ( V osc S = I 15 /V 1;2 = ; f IF = 455 khz f i = 1 MHz; V 3 = V 8 V 1 ( mv V 1 = f ( V 9 R = 1.5 kω V osc ( mv V 9 ( mv 8 5 V 3 ( mv 4 V 3 = f ( V gohf f i = 1 MHz 5 V 3 ( mv 4 V 3 = f ( V gohf f i = 1 MHz V gohf ( µv V gohf ( µv 1 12/95

7 V AF ( mv 4 V AF = f ( V iif V 3 = parameter f IF = 455 khz m =.8; f m = 1 khz THD ( % THD = f ( V iif f IF = 455 khz m =.8; f m = 1 khz V iif ( µv V iif ( µv 1 V 1 (mv 5 V 1 = f ( V gohf f i = 1 MHz V 9 (mv 8 V 9 = f ( V iif f IF = 455 khz V gohf (µv V iif (µv 12/95 7

8 I CC ( ma 18 I CC = f ( V gohf = V AF (mv 4 V AF = f ( V gohf = parameter f IF = 455 khz m =.8; f m = 1 khz (V V gohf (µv V AF (mv 3 V AF = f ( V gohf f IF = 455 khz f m = 1 khz; m =.8 THD ( % 8 THD = f ( V oghf f IF = 455 khz f m = 1 khz; m = V gohf (µv V gohf (mv /95

9 8 S+N (db N S+N = f (P N gmax = 9 V f i = 1 MHz f m = 1 khz; m =.3 R g = parameter V 1 (mv 5 4 V 1 = f ( V iif = parameter f IF = 455 khz m =.8; f m = 1 khz kΩ 4.7 kω 3 Ω 25 Ω P gmax = V 2 go 4Rg P gmax (µw V iif (µv 1 8 V 3 (mv HFgain = f ( V 3 V 15 = 5 mv const. f ihf = 1 MHz 8 V 9 (mv IFgain = f ( V 9 V AF = 2 mv const. f iif = 455 khz f m = 1 khz; m =.8 5 V 9 V HFgain (db IFgain (db 12/95 9

10 8 V 7 (mv 9 V V 7 = f ( V 9 V iif = 1 µv f i = 455 khz V 15 (mv 4 V 15 = f ( V 3 V gohf = 7 µv f i = 1 MHz 3 9 V 4 5 V 5 V V 9 (mv V 3 (mv Application examples TCA 44 S4 S3 C13 W1a 33 W1b V gohf ~ D2 C13 1n S2 Fi1 W2 RG C12 1n W2 Fi W1 C12 1.5n 1 S5 R 1.5k 1 C9 1n W2 TCA a Fi2 W1 b S Rp2 C8 1.5n 14 7 Fi3 W1 C11 1n x A C14 1n D1 Rp3 C5 1.5n C1 4.7µ R9 R5 12k V IF C7 4.7µ V AF C 3.3n 25Ω RG 1Ω R1 1.8k C1 2µ R2 8.2k C2 1n C3 1n S1 C4 4.7µ R4 39k R /95

11 TCA 44 T + S2 1n +5% -2% 47µ ±5% 1.5k ±2% W2 W1 1n +5% -2% Rp2 1.5n ±2.5% S3 33p ±2.5% W1a W1b 1n +5% -2% TCA 44 T A x 4.7µ ±5% V gohf ~ RG W1 Rp3 1.5n ±2.5% 12k ±2% 3.3n +5% -2% V AF 25Ω RG 1Ω 1.8k ±2% 2µ ±2% 8.2k ±5% 1n +5% -2% 1n +5% -2% S1 4.7µ ±5% 1 ±2% 39k ±2% Application hints The PCB is to arrange such that there are maximum ground lines (ground area voltage supply has to be blocked to ground by a capacitor of nf in order to avoid distortions. Blocking should be as close as possible to the circuit. The RF circuit has to layout such that 15 mv (rms oscillator voltage are applied to pin 5. Symmetrically applying an external oscillator is possible to pin 4 or pin 5. The unused input must be connected to ground via capacitor and in the same time be connected to supply voltage at pin. It is recommendable to profide off earth connections 1 and 3, because in this way common - mode interferences more effectively can be suppessed. Single - sided capacitive control of pin 1 and 2 is possible, the unused input must be connected to ground via capacitor. Mixer outputs 15 and 1 can be used equivalently. Load resistances of the mixer (IF selection at pin 15 respectively pin 1 should run to approximately 7 kω. To avoid saturation of the multiplier the maximum peak voltage occuring during operation should not exceed the level ( - 3 V IF response to voltage from pin 15 respectively pin 1 to pin 12 should be approximately - 18 db that the control characteristics of IF - and RF - part optimally be matched. Peak voltage at pin 7 occuring during operation should not exceed 2 V that the IF output does not go into saturation. All the RF bypass capacitors should amount to 1 nf. Sufficient decoupling of wavemagnet and oscillator coil is to be taken into consideration. All components and parts must be carefully proportioned in order to obtain optimum wise characteristics. Wavemagnets applied should so much mass as possible. The transformation ratio of the input circuitry should run to In order to improve RF response characteristic a RF preselector can be additionally preceded or the wavemagnet can be tighty coupled by means of an emitter follower impedance transformer. Improvement of signal - to - noise ratio at average input voltages can be obtained by delayed control of the RF part. Control should be start at approximately mv. Reprinting is generally permitted, indicating the source. However, our consent must be obtained in all cases. SMI reserves the right to make changes in specifications at any time and without notice. The information and suggestions are given without obligation and cannot given rise to any liability, they do not indicate the availability of the components mentioned. The information included herein is believed to be accurate and reliable. However, the SMI assumes no responsibility for its use; nor for any infringements of patents or of other rights of third parties which may result from its use. 12/95 11