TCA440T中文资料
AM -Receiver Circuit
Package
Technical Data
TCA 440 / T
Edition 12/95
12/951
Description
This is an efficient bipolar monolithic circuit to apply in battery -powered or mains -operated radio receivers up to 30 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 60 dB control range
? external demodulator (diode)
? wide range of supply voltage between 4.5 and 15 V
Pin configuration
1RF prestage, input 19input IF control amplifier
2RF prestage, input 210indicator output IF control amplifier 3RF control amplifier input11IF blocking
4oscillator circuit pin 112input lF amplifier
5oscillator circuit pin 213IF blocking
6oscillator circuit pin 314supply voltage
7IF output15mixer output 1
8ground16mixer output 2
Block diagram
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 100 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 460 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 CC 4.515.0V
Junction temperature T j150°C
Ambient operating temperature T a-1580°C
Storage temperature T s-40125°C
Total thermal resistance R thja120K/W Recommended operational conditions
min max unit
Supply voltage V CC 4.515V
Ambient operating temperature T a-1070°C
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Characteristics
refer to application examples, f i= 1 MHz, f osc= 1.455 kHz, f lF= 455 kHz, V CC= 9 V, f m= 1 kHz, m = 0.8, voltages refer to ground, T a= 20 to 25 °C, unless specified otherwise
min typ max unit Current and voltage supply
(no RF signal)
Supply voltage V14-8 4.5915V Current consumption
V14-8= 4.5 V I147mA
V14-8= 9 V I1410.516mA
V14-8= 15 V I1412mA Entire receiver
RF level variation
with ?V NF= 6 dB?V RF65dB
with ?V NF= 10 dB?V RF80dB
NF output voltages
(symmetrically measured at 1-2)
V iHF= 20 μV, m = 0.8V NF(rms)60140mV
V iHF= 1 mV, m = 0.8V NF(rms)260mV
V iHF= 500 mV, m = 0.8V NF(rms)100350560mV
V iHF= 20 μV, m = 0.3V NF(rms)50mV
V iHF= 1 mV, m = 0.3V NF(rms)100mV
V iHF= 500 mV, m = 0.3V NF(rms)130mV
RF input sensitivity
measured at 60 ?, m = 0.3,
R G= 540 ?
signal-to-noise ratio
S + N/N = 6 dB V iRF1μV
S + N/N = 26 dB V iRF7μV
S + N/N = 58 dB V iRF1mV
Maximum RF input voltage V iHF 1.5V (THD = 10 %)
Total harmonic distortion
V HF= 500 mV THD 4.510%
V HF= 30 mV THD 2.88%
RF part
Input frequency range f iHF050MHz Output frequency
f|F= f osc-f iHF f IF455kHz Control range?G V38dB
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min typ max unit
IF suppression a lF20dB between 1 -2 and 15
RF input impedance
unbalanced coupling
V iHFmax Z i 2 II 5k?IIpF
V iHFmin Z i 2.2 II 1.5k?IIpF balanced coupling
V iHFmax Z i 4.5k?
V iHFmin Z i 4.5 II 1.5k?IIpF Mixer output impedance
(pin 15 or 16)Z o250 II 4.5k?IIpF Steepness S HF28mS
IF part
Input frequency range f ilF02MHz
Control range?G V62dB
f ilF= 455 kHz, ?V NF= 10 dB
Start of control V ctrlF140μV (?V iIF/ ?V NF= 10 dB / 3 dB)
maximum IF input voltage V ilFmax200mV (THD NF= 10 %)
NF output voltage
applied to 60 ?
V ZF= 30 μV V NF(rms)50mV
V ZF= 3 mV V NF(rms)200mV
V ZF= 3 mV; m = 0.3V NF(rms)70mV
IF input impedance
(unbanlanced coupling)Z ilF 3 II 3k?llpF
IF output impedance Z O200 II 8k?IIpF (pin 7)
Indication instrument
Recommended indication instruments: 500 μA (R i= 800 ?)
300 μA (R i= 1.5 k?)
For indication a voltage source of 600 m V(EMF)and an internal source impedance of 400 ?is available.
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Dependences
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Application examples
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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 10...100 nF in order to avoid distortions. Blocking should be as close as possible to the circuit.
The RF circuit has to layout such that 150 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 6.
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 16 can be used equivalently.
Load resistances of the mixer (IF selection) at pin 15 respectively pin 16 should run to approximately 7 k?.
To avoid saturation of the multiplier the maximum peak voltage occuring during operation should not exceed the level (V CC-3 V) IF response to voltage from pin 15 respectively pin 16 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 100 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 10...12.
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 1...2 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.
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