tda1072a.pdf

INTEGRATED CIRCUITS

DATA SHEET

TDA1072A

AM receiver circuit

Product speciﬁcation

File under Integrated Circuits, IC01

May 1984

Philips Semiconductors

Product speciﬁcation

AM receiver circuit

TDA1072A

GENERAL DESCRIPTION

The TDA1072A integrated AM receiver circuit performs the active and part of the filtering functions of an AM radio

receiver. It 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

V P

7,5 to 18 V

Supply current range

I P

15 to 30 mA

R.F. input voltage for S + N/N = 6 dB at m = 30%

V i

typ.

1,5

m V

R.F. input voltage for 3% total harmonic

distortion (THD) at m = 80%

V i

typ.

500 mV

A.F. output voltage with V i = 2 mV;

f i = 1 MHz; m = 30% and f m = 400 Hz

V o(af)

typ.

310 mV

A.G.C. range: change of V i for 1 dB change of V o(af)

typ.

86 dB

Field strength indicator voltage at

V i = 500 mV; R L(9) = 2,7 k

V IND

typ.

2,8 V

PACKAGE OUTLINE

16-lead DIL; plastic (SOT38); SOT38-1; 1996 August 09.

May 1984

Philips Semiconductors

Product speciﬁcation

AM receiver circuit

TDA1072A

(1) Coil data: TOKO sample no. 7XNS-A7523DY; L1 : N1/N2 = 12/32; Q o = 65; Q B = 57.

Filter data: Z F = 700 W at R 3-4 = 3 k W ; Z I = 4,8 k W .

Fig.1 Block diagram and test circuit (connections shown in broken lines are not part of the test circuit).

May 1984

Philips Semiconductors

Product speciﬁcation

AM 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 connection. The oscillator

is voltage-controlled 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 V 11-16 . An extra

buffered oscillator output (pin 10) is available for driving a synthesizer. If this is not needed, resistor R L(10) 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 smaller 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 L(9) can be omitted.

Standby switch

This switch is primarily intended for AM/FM band switching. 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

Philips Semiconductors

Product speciﬁcation

AM receiver circuit

TDA1072A

RATINGS

Limiting values in accordance with the Absolute Maximum Rating System (IEC 134)

Supply voltage

V P = V 13-16

max.

20 V

Total power dissipation

P tot

max.

875 mW

Input voltage

ï V 14-15 ï

max.

12 V

V 14-16 ,

V 15-16

max.

0,6 V

V 14-16 , V 15-16

max.

V P V

Input current

I 14 ï

I 15 ï

max.

200 mA

Operating ambient temperature range

T amb

- 40 to

+ 80

° C

Storage temperature range

T stg

55 to

150

Junction temperature

T j

max.

125

THERMAL RESISTANCE

From junction to ambient

R th j-a

K/W

DEVICE CHARACTERISTICS

V P = V 13-16 = 8,5 V; T amb = 25

C; f i = 1 MHz; f m = 400 Hz; m = 30%; f if = 460 kHz; measured in test circuit of Fig.1;

unless otherwise speciﬁed

PARAMETER

SYMBOL

MIN.

TYP. MAX.

UNIT

Supplies

Supply voltage

V P = V 13-16

7,5

8,5

Supply current

I P = I 13

R.F. stage and mixer

Input voltage (d.c. value)

V 14-16 , V 15-16

V P /2

R.F. input impedance at V i <

300

R 14-16 , R 15-16

5,5

C 14-16 , C 15-16

R.F. input impedance at V i >

10 mV

R 14-16 , R 15-16

C 14-16 , C 15-16

I.F. output impedance

R 1-16

500

C 1-16

Conversion transconductance

before start of a.g.c.

I 1 /V i

6,5

mA/V

Maximum i.f. output voltage, inductive

coupling to pin 1

V 1-13(p-p)

D.C. value of output current (pin 1)

at V i = 0 V

I 1

1,2

A.G.C. range of input stage

R.F. signal handling capability:

input voltage for THD = 3% at m = 80%

V i(rms)

500

May 1984

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