 |
Moteur de recherche de fiches techniques de composants électroniques |
|
|
Moteur de recherche de fiches techniques de composants électroniques |
|
UAA2080T Fiches technique(PDF) 19 Page - NXP Semiconductors |
|
||||||||||||||||||||||||||||||
UAA2080T Fiches technique(HTML) 19 Page - NXP Semiconductors |
|
|
19 / 44 page  1996 Jan 15 19 Philips Semiconductors Product specification Advanced pager receiver UAA2080 FUNCTIONAL DESCRIPTION The complete circuit consists of the following functional blocks as shown in Figs 1 to 6. Radio frequency amplifier The RF amplifier is an emitter-coupled pair driving a balanced cascode stage, which drives an external balanced tuned circuit. Its bias current is set by an external 300 Ω resistor R1 to typically 770 µA. With this bias current the optimum source resistance is 1.3 k Ω at VHF and 1.0 k Ω at UHF. At 930 MHz a higher bias current is required to achieve optimum gain. A value of 120 Ω is used for R1, which corresponds with a bias current of approximately 1.3 mA and an optimum source resistance of approximately 600 Ω.The capacitors C1 and C2 transform a 50 Ω source resistance to this optimum value. The output drives a tuned circuit with capacitive divider (C7, C8 and C9) to provide maximum power transfer to the phase-splitting network and the mixers. Mixers The double balanced mixers consist of common base input stages and upper switching stages driven from the frequency multiplier. The 300 Ω input impedance of each mixer acts together with external components (C10, C11; L4, L5 respectively) as phase shifter/power splitter to provide a differential phase shift of 90 degrees between the I channel and the Q channel. At 930 MHz all external phase shifter components are inductive (L10, L11; L4, L5). Oscillator The oscillator is based on a transistor in common collector configuration. It is followed by a cascode stage driving a tuned circuit which provides the signal for the frequency multiplier. The oscillator bias current (typically 250 µA) is determined by the 1.8 k Ω external resistor R5. The oscillator frequency is controlled by an external 3rd overtone crystal in parallel resonance mode. External capacitors between base and emitter (C17) and from emitter to ground (C16) make the oscillator transistor appear as having a negative resistance for small signals; this causes the oscillator to start. Inductance L9 connected in parallel with capacitor C16 to the emitter of the oscillator transistor prevents oscillation at the fundamental frequency of the crystal. The resonant circuit at output pin OSC selects the second harmonic of the oscillator frequency. In other applications a different multiplication factor may be chosen. At 930 MHz an external oscillator circuit is required to provide sufficient local oscillator signal for the frequency multiplier. Frequency multiplier The frequency multiplier is an emitter-coupled pair driving an external balanced tuned circuit. Its bias current is set by external resistor R4 to typically 190 µA (173 MHz), 350 µA (470 MHz) and 1 mA (930 MHz). The oscillator signal is internally AC coupled to one input of the emitter-coupled pair while the other input is internally grounded via a capacitor. The frequency multiplier output signal between pins VO1MUL and VO2MUL drives the upper switching stages of the mixers. The bias voltage on pins VO1MUL and VO2MUL is set by external resistor R3 to allow sufficient voltage swing at the mixer outputs. The value of R3 depends on the operating frequency: 1.5 k Ω (173 MHz), 820 Ω (470 MHz) and 330 Ω (930 MHz). Low noise amplifiers, active filters and gyrator filters The low noise amplifiers ensure that the noise of the following stages does not affect the overall noise figure. The following active filters before the gyrator filters reduce the levels of large signals from adjacent channels. Internal AC couplings block DC offsets from the gyrator filter inputs. The gyrator filters implement the transfer function of a 7th order elliptic filter. Their cut-off frequencies are determined by the 47 k Ω external resistor R2 between pins RGYR and COM. The gyrator filter output signals are available on IF test pins TPI and TPQ. Limiters The gyrator filter output signals are amplified in the limiter amplifiers to obtain IF signals with removed amplitude information. Demodulator The limiter amplifier output signals are fed to the demodulator. The demodulator output DO is going LOW or HIGH depending upon which of the input signals has a phase lead. |
Numéro de pièce similaire - UAA2080T |
|
Description similaire - UAA2080T |
|
|
Lien URL |
| Politique de confidentialité |
| ALLDATASHEET.FR |
| ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
French ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
