HA12181FP AM Radio Noise Reduction System ADE-207-171A (Z) 2nd. Edition June 1997 Functions • Buffer amp. for audio • Linear approximate circuit for noise reduction • IF Amp., detector, audio amp. and AGC circuit for noise detection • Gate pulse generator Features • High noise cancelling capacity: 46 dB typ. • Less gain loss: GV = –0.5 dB typ. • Low total harmonic destortion and high signal-to noise ratio: THD = 0.06% typ., S/N = 75 dB typ. • Operation supply voltage range: 7.0 V to 10 V (8.2 V typ.) • Less external parts count Rev.2, Jun. 1997, page 2 of 21 ANT RF OSC MIX 1st IFT IF AM-IC Det. 2nd IFT 7 4 C513 1µ + 3 AF Input R506 12 k C501 1000 p 16 IF Input SW1 C500 0.033µ 2 C503 SW2 5 Pulse Det. Det. Capacitor for Pahse C512 0.068µ Level Diff. Det. Circuit Phase Circuit SW3 HPF1 LPF + C502 0.01µ 3.3µ Det. 1 14 IF AGC Stabilized Voltage Circuit Stabi. Volt. IF Amp. LPF R500 100 k IF AGC HPF AF AGC 6 Capacitor for Hold C511 0.033µ Stabilized Current Circuit (waveform compensation) 15 (2) (1) 10 Buffer Amp. 9 Gate pulse (2) Gate pulse (1) Pulse Det.(2) Gate pulse Gen. Unit 11 13 + VCC (8.2 V) Gate Time Constant C507 2200 p C506 100µ R:Ω C:F AF Output Capacitor C509 + for By-pass R503 0.033µ 180 k C508 C510 R504 1µ 0.033µ Capacitor 4.7 k for waveform compensation SW5 SW4 12 R502 22 k Pulse Det.(1) R505 47 k AF AGC Noise AGC OR 8 Hight-pass Amp. (waveform compensation) AF Amp. C504 0.22µ HA12181FP Block Diagram HA12181FP Table of Pin Description and External Parts External parts No. of pin Name 1 DC voltage (V) (No Function input) Equivalent circuit IF AGC Time No. 2.7 constant for IF AGC. 1 R500 100k 2 3 Bias1 AF input Bypass for voltage Stabi. 3.2 Input of AF. 3.3 Influence of External parts Larger than recom- recommended mended value value Smaller than recommended value R500 100 K Longer Longer C502 3.3 µ time to stabilize AGC. distortion of recover. C500 0.033 µ — Increased noise. C513 1µ — — R506 12 K Cut off frequency of L·P·F and H·P·F shifted lower. Cut off frequency of L·P·F and H·P·F shifted higher. C512 0.068 µ Must be used on the recommended value. C502 3.3µ + 2 C500 0.033µ 20k 3 + C513 AF IN 4 5 Bias2 Decide 1.3 the current of filter network. Phase Phase circuit 4 3.3 5 C512 0.068µ Rev.2, Jun. 1997, page 3 of 21 HA12181FP Table of Pin Description and External Parts (cont) External parts No. of pin Name 6 Hold DC voltage (V) (No Function input) Equivalent circuit Hold of level difference. 3.3 Influence of External parts No. Larger than recom- recommended mended value value C511 0.033 µ Must be used on the recommended value. — — — C510 0.033 µ Must be used on the recommended value. C508 1µ Output DC cut R504 4.7 K Output load C509 0.033 µ Must be used on the recommended value. Smaller than recommended value 6 C511 0.033µ 7 GND GND 8 HighPass. High3.3 Pass AMP. (Waveform Compensation) — — 8 C510 0.033µ 9 AF out Output of 3.3 AF + 9 C508 1µ 10 Wave form R504 4.7k Wave3.3 form Compensation 10 C509 0.033µ Rev.2, Jun. 1997, page 4 of 21 HA12181FP Table of Pin Description and External Parts (cont) External parts No. of pin Name 11 Gate DC voltage (V) (No Function input) Equivalent circuit Gate pulse generation 4.5V No. Influence of External parts Larger than recom- recommended mended value value Smaller than recommended value R503 180 K Gate Gate C507 2200 P pulse width become wider. pulse width become narrow. R502 22 K Higher noise detection sensitivity. Lower noise detection sensitivity. — — — — C503 0.01 µ — — R505 47 K Longer Miss- C504 0.22 µ time to stabilize AGC. operaton in noise detector. 0 11 C507 2200p 12 Vth Determi- 1.1 nation of noise detection sensitivit y 13 VCC VCC 14 IF Det. IF AGC detector 8.2 R503 180k 12 R502 22k — 3.3 14 13 C503 0.01µ 15 AF Time AGC constant for AF AGC 0 15 C504 0.22µ R505 47k Rev.2, Jun. 1997, page 5 of 21 HA12181FP Table of Pin Description and External Parts (cont) External parts No. of pin Name DC voltage (V) (No Function input) Equivalent circuit 16 IF input IF in Influence of External parts Larger than recom- recommended mended value value No. 1.3 IF Input Coupling — Instability 30k 16 C501 1000p IF IN Absolute Maximum Ratings (Ta = 25°C) Item Symbol Rating Unit Supply voltage VCC 16 V 1 Power dissipation Pd 400* mW Operating temperature Topr –40 to +85 °C Storage temperature Tstg –55 to +125 °C Note: 1. Value at Ta = 85°C Rev.2, Jun. 1997, page 6 of 21 Smaller than recommended value HA12181FP Electrical Characteristics (Tentative) (VCC = 8.2 V, Ta = 25°C, Pin 3 input: Vin = 100 mVrms, f = 1 KHz, Pin 16 input: Vin = 74 dBµ, fc = 450 KHz, fm = 1 KHz, m = 30%) Item Symbol Min Typ Max Unit Test conditions Supply current ICC — 11.0 — mA No input signal, IC only Output voltage Vout 70 95 120 mVrms Pin 3 input only Total harmonic distortion THD1 — 0.06 0.3 % Signal-to-noise ratio S/N (1) 60 75 — dB Pin 3 input Vin = 100 mVrms (Reference), Rg = 10 KΩ Strong input total harmonic distortion THD2 — 1.0 2.5 % Pin 3 input Vin = 500 mVrms Recovered output voltage VO (AF) 50 78 120 mVrms Pin 16 input only Recovered output signal-tonoise-ratio S/N (2) 35 45 — dB Noise suppression ratio NSR 35 46 — dB 100mV Input the waveform below. Pin 3 input Vin = 100 mVrms (Reference) no input sine wave 10µs Pin 16 Input 2ms Figure 1 Input Waveform at Measurement of Noise Suppression Ratio Rev.2, Jun. 1997, page 7 of 21 HA12181FP Test Circuit VCC (8.2V) Det.Out + B A R505 C504 47k 0.22µ R502 R503 C507 C509 15k 180k 2200p 0.033µ + C503 0.01µ IF-IN PULSE-IN R504 4.7k C OUT C506 100µ C501 1000p 50 + C508 1µ 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 AM-SG AF-IN + C513 1µ 50 + C502 R500 100k 3.3µ C500 0.033µ R506 12k C512 C511 0.068µ 0.033µ C510 0.033µ AF-SG Unit R:Ω C:F Note: 1. Resistors tolerance are within ±5%. 2. Capacitors tolerance (C509 to C512) are within ±5%, other capacitor are within ±10%. Operation Principle ANT. Noise Detector 16 IF 3 Processing Waveform Circuit B 1st IFT A RF CONV. IF DET 9 C AM-IC HA12181FP Figure 2 System Block Diagram of AM Radio Rev.2, Jun. 1997, page 8 of 21 D Out HA12181FP A system block diagram of AM Radio using the HA12181FP is shown in Figure 2 and waveforms at each point in the system are illustrated in Figure 3. For AM wave with impulse noise from ANT, the pulse spreads its width each time when the AM wave passes through a selection filter. The pulse width becomes the order of several hundred microseconds at detector output (Point C). A radio without a noise canceller produces large noise to the audience. This IC perfectly detects every noise by using the signals from 1st IFT (Point B) in front of the narrow band filter. The wave process circuit approximates the voltage linearly at the pulse to reduce the noise in the output. The principle for wave processing follows. Further investigation make it clear that the pulse width of impulse noise is constant (several handred microseconds) and independent of the waveform or waveheight. Therefore the former and later voltage (VA, VB) of the pulse can be found at the same time (T1) by means of the wave and the delayed one for this time, as shown in the right figure. Each Point in the Figure Waveform including Noise A Narrower Pulse Width and Higher Wave Height B Point D VB Point C C VA Wider Pulse Width and Lower Wave Height T1 T2 D Noiseless Figure 3 Waveforms at Each Point in the System In an actual circuit, the differential voltage between input and output of phase shift circuit is changed to the capacitor C511 at pin 6. At the time of T1, when the switch turns to the noise processing mode (the switch positions in Figure 4 are inverted), the voltage difference (VA – VB) is held in C511. C509 at pin 10 is changed by the differential voltage between the held voltage and the output voltage at pin 9 (VA): VA – (VA – VB) = VB. Rev.2, Jun. 1997, page 9 of 21 HA12181FP As the initial voltage of C509 is equal to the output voltage (VA) before the switch change, the voltage between terminals of C509 is changed from VA to VB. The waveform which change up to C509 becomes the output, because the voltage of C509 appears at pin 9 through the buffer. The changed up waveform of C509 is almost linearly approximated because of the constant current change by the feedback from the output at pin 9. At the time of T2 when the awitches change to the normal mode (the switch position in Figure 4), the output recovers smoothly as the voltage of C509 is VB. However the unmatch of the wave delay time due to the pulse width or the phase circuit and the offset of circuit make a slight step difference on the waverform at the moment of switch change. LPF, consisting of R1 and C509 make it smooth. The frequency characteristics, which is detriorated by LPF in the normalmode, is compensated so that it might become flat. C509 and C510 should have the same capacity, and the tolerance must be within ±5%. Phase Circuit 3 + Subtraction – Circuit + Constant Current – Circuit(Subtraction Buffer R2 Circuit) 5 6 C512 R1 HPFAmp. C511 8 10 C510 Figure 4 Waveform Processing Circuit Rev.2, Jun. 1997, page 10 of 21 C509 9 Out 50 AM SG. Pulse SG. 50 Two signals dummy ANT. RF OSC MIX 1st IFT IF AM-IC Det. 2nd IFT 7 4 C513 1µ + 3 AF Input R506 12 k C501 1000 p 16 IF Input C500 0.033µ 2 C503 SW2 5 Pulse Det. Det. Capacitor for Pahse C512 0.068µ Level Diff. Det. Circuit Phase Circuit SW3 HPF1 LPF + C502 0.01µ 3.3µ Det. 1 14 IF AGC Stabilized Voltage Circuit SW1 Stabi. Volt. IF Amp. LPF R500 100 k IF AGC HPF AF AGC 6 Capacitor for Hold C511 0.033µ Stabilized Current Circuit (waveform compensation) 15 8 (2) (1) Buffer Amp. Gate pulse (2) Gate pulse (1) Pulse Det.(2) Gate pulse Gen. + VCC (8.2 V) C506 100µ Meter 13 Unit R:Ω C:F 10 9 11 Gate Time AF Output Capacitor C509 Constant + for By-pass R503 0.033µ C507 180 k C508 C510 2200 p 0.033µ Capacitor 1µ R504 for waveform 4.7 k Noise compensation SW5 SW4 12 R502 22 k Pulse Det.(1) R505 47 k AF AGC Noise AGC OR Hight-pass Amp. (waveform compensation) AF Amp. C504 0.22µ HA12181FP Evaluation Circuit for Noise Reduction Effect Rev.2, Jun. 1997, page 11 of 21 HA12181FP Example of Noise Reduction Effect 20 VCC=8.2V AM SG : fc=999kHz, m=30%, fm=1kHz Pulse : No input 10 Vout 0 Two Signals dummy ANT. Output (dB) –10 NRoff 50Ω Pulse SG. 50Ω 16Ω 16Ω 16Ω 15p To ANT 30Ω 65p Pulse SG Output (EMF) AM SG. –20 10µs 100mVP-P 2µs –30 Figure.2 NRon AM SG : fc=999kHz, no mod. Pulse SG : Refer to Figure.2 Noise –40 Pulse : No input –50 –60 0 10 20 30 40 50 60 70 80 AM SG Output (EMF) (dBµ) 90 100 110 120 20 VCC=8.2V AM SG : fc=999kHz, m=30%, fm=1kHz Pulse : No input 10 Vout 0 Two Signals dummy ANT. Output (dB) –10 50Ω 16Ω 16Ω 15p Pulse SG. NRoff –20 50Ω 16Ω 30Ω 65p To ANT Pulse SG Output (EMF) AM SG. 10µs NRon 100mVP-P 10µs –30 Figure.3 –40 Noise AM SG : fc=999kHz, no mod. Pulse SG : Refer to Figure.2 –50 –60 0 10 20 Rev.2, Jun. 1997, page 12 of 21 30 40 50 60 70 80 AM SG Output (EMF) (dBµ) 90 100 110 120 HA12181FP PC Board Layout Pattern C507 VCC C506 + R503 C504 R502 R501 R504 C503 C508 C501 C509 + IF in C513 16 R506 C502 R500 Vout C510 C511 + C512 C505 AF in + HA12181FP (Top view) FN-8648 HA12181FP (Bottom view) Rev.2, Jun. 1997, page 13 of 21 HA12181FP 10 0 -2 -4 Vin max (Vrms) Vout (dB) Main Characteristics Vout : Vin = 100 mVrms const Vout (0 dB = 96 mVrms) 2.0 1.5 -6 1.0 Vin Max (THD ≥ 1.0%) -8 -10 -12 0.5 0 40 100 200 400 1k 2k 4k 10 k 20 k f (Hz) 0.5 Vin = 100 mVrms THD (%) 0.4 0.3 0.2 0.1 0 40 100 200 400 f (Hz) Rev.2, Jun. 1997, page 14 of 21 1k 2k 4k 10 k 50 k HA12181FP 10 Vo (AF) : 0 dB = 76 mVrms 0 -10 fc = 450 kHz, m = 30%, fm = 1kHz -30 -40 Noise (no modulation) -50 -60 -70 10 20 30 40 50 60 70 80 90 100 110 120 Vin (EMF) (dBµ) 50 20 10 V pulse (mVp-p) Vout (dB) -20 Pulse input at Gate ON 10µs V pulse 2ms 5 2 1 0.5 0.2 1k 5k 10 k 50 k 100 k R (Ω) Rev.2, Jun. 1997, page 15 of 21 Vout (mVrms) THD1 (%) HA12181FP 120 Vout 0.5 100 0.4 80 0.3 60 0.2 40 0.1 20 0 0 THD1 6 7 8 9 10 11 12 13 14 15 16 S/N1 (dB) THD2 (%) VCC (V) 120 1.0 100 S : 100 mVrms = 0 dB 0.8 80 0.6 60 0.4 40 0.2 20 0 0 S/N1 N : no-input THD2 (Vin = 500 mVrms, f = 1 kHz) 6 7 8 9 10 11 VCC (V) Rev.2, Jun. 1997, page 16 of 21 12 13 14 15 16 Vo (AF) (mVrms) S/N2 (dB) HA12181FP 60 120 S/N2 50 100 40 80 30 60 20 40 10 20 0 0 Vo (AF) Vin = 74 dBµ fc = 450 kHz fm = 1 kHZ m = 30% 6 7 8 9 10 11 12 13 14 15 16 14 15 16 VCC (V) 60 60 50 50 40 40 30 30 20 20 NSR (pulse input) ICC (no-input) 10 10 0 0 6 7 8 9 10 11 12 13 VCC (V) Rev.2, Jun. 1997, page 17 of 21 V pulse (mVp-p) HA12181FP 1.0 0.8 V pulse (Pulse input level at Gate on) 0.6 0.4 0.2 0 6 7 8 9 10 11 12 13 14 15 Vout (AF) (mVrms) THD1 (%) VCC (V) 0.5 100 Vout 0.4 80 0.3 60 0.2 40 0.1 20 VCC = 8.2 V Vin = 100 mVrms, f = 1 kHz THD1 0 0 -40 -20 0 20 40 Ta ( C) Rev.2, Jun. 1997, page 18 of 21 60 80 100 16 NSR (dB) ICC (mA) HA12181FP 60 60 VCC = 8.2 V 50 50 40 40 30 30 20 20 NSR (pulse input) ICC (no-input) 10 0 10 0 -40 -20 0 20 40 60 80 100 Ta ( C) Rev.2, Jun. 1997, page 19 of 21 HA12181FP Package Dimensions Unit: mm 10.06 10.5 Max 9 1 8 1.27 0.42 ± 0.08 0.40 ± 0.06 0.10 ± 0.10 0.80 Max 0.22 ± 0.05 0.20 ± 0.04 2.20 Max 5.5 16 0.20 7.80 +– 0.30 1.15 0 – 8˚ 0.70 ± 0.20 0.15 0.12 M Hitachi Code JEDEC Code EIAJ Code Weight Rev.2, Jun. 1997, page 20 of 21 FP-16DA — SC-530-16C 0.24 g HA12181FP Disclaimer 1. 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(Taipei Branch Office) 4/F, No. 167, Tun Hwa North Road, Hung-Kuo Building, Taipei (105), Taiwan Tel : <886>-(2)-2718-3666 Fax : <886>-(2)-2718-8180 Telex : 23222 HAS-TP URL : http://www.hitachi.com.tw Hitachi Asia (Hong Kong) Ltd. Group III (Electronic Components) 7/F., North Tower, World Finance Centre, Harbour City, Canton Road Tsim Sha Tsui, Kowloon, Hong Kong Tel : <852>-(2)-735-9218 Fax : <852>-(2)-730-0281 URL : http://www.hitachi.com.hk Copyright Hitachi, Ltd., 2000. All rights reserved. Printed in Japan. Colophon 2.0 Rev.2, Jun. 1997, page 21 of 21