TDA1072ATD NXP Semiconductors, TDA1072ATD Datasheet - Page 4

• Manufacturer Part Number: TDA1072ATD
• Description: RF Receiver AM RECEIVER CIRCUIT
• Manufacturer: NXP Semiconductors
• Type: Receiverr

Specifications of TDA1072ATD

• Package / Case: SOT-109
• Operating Supply Voltage: 8.5 V
• Maximum Operating Temperature: + 80 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: TDA1072AT/V4,112

Philips Semiconductors
FUNCTIONAL DESCRIPTION
Gain-controlled RF stage and mixer
The differential amplifier in the RF stage employs an AGC negative feedback network to provide a wide dynamic range.
Very good cross-modulation behaviour is achieved by AGC delays at the various signal stages. Large signals are
handled with low distortion and the S/N ratio of small signals is also improved. Low noise working is achieved in the
differential amplifier by using transistors with a low base resistance.
A double balanced mixer provides the IF output 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
buffered oscillator output is available for driving a synthesizer. If this is not needed, resistor R
Gain-controlled IF amplifier
This amplifier comprises two cascaded, variable-gain differential amplifier stages coupled by a band-pass filter. Both
stages are gain-controlled by the AGC negative feedback network.
Detector
The full-wave, balanced envelope detector has very low distortion over a wide dynamic range. The residual IF carrier is
blocked from the signal path by an internal low-pass filter.
AF preamplifier
This stage preamplifies the audio frequency output. The amplifier output stage uses an emitter follower with a series
resistor which, together with an external capacitor, provides the required low-pass filtering for AF signals.
AGC amplifier
The AGC amplifier provides a control voltage which is proportional to the carrier amplitude. Second-order filtering of the
AGC voltage achieves signals with very little distortion, even at low audio frequencies. This method of filtering also gives
a fast AGC settling time which is advantageous for electronic search tuning. The AGC settling time can be further
reduced by using capacitors of smaller value in the external filter. The AGC voltage is fed to the RF and IF stages via
suitable AGC 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 field strength information is not needed, R
Standby switch
This switch is primariIy intended for AM/FM band switching. During standby mode the oscillator, mixer and demodulator
are switched off.
Short-circuit protection
All pins have short-circuit protection to ground.
March 1989
AM receiver circuit
4
L(9)
can be omitted.
L(10)
can be omitted.
Product specification
TDA1072AT
11-16
. An extra