Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
MC13030DW Datasheet(PDF) 9 Page - Motorola, Inc |
|
MC13030DW Datasheet(HTML) 9 Page - Motorola, Inc |
9 / 16 page MC13030 9 MOTOROLA ANALOG IC DEVICE DATA PIN FUNCTION DESCRIPTION (continued) Pin No. Description Internal Equivalent Circuit 26 VCC Vref 26 75 VCO Reference The first oscillator coil is connected from Pin 26 to 27. Pin 26 must be bypassed to ground with a capacitor which has a low impedance at the oscillator frequency. This capacitor also will reduce the phase noise of the VCO. 27 7.5 k 27 to Mixer1 VCO The VCO is a negative resistance type and has an internal level control circuit so a tapped coil or one with a secondary is not needed. The level is fixed at 0.8 Vpp so the oscillator signal does not modulate the tuning diode, thus keeping the distortion low. The oscillator stray capacitance is ≈ 12 pF and the tuned circuit impedance should be greater than 3.0 k to guarantee oscillation. Oscillator range is up to 45 MHz so it can be used for SW receivers. 28 100 28 VCO Out The output level is 240 mVrms (108 dB µ), high enough to drive any CMOS synthesizer. AM CAR RADIO DESIGN NOTES The MC13030 AM Radio IC is intended for dual conversion AM radios. In most cases, the 1st IF frequency (FIF1) is upconverted above the highest input frequency. The first oscillator (VCO) is tuned by a synthesizer and operates at Fin + FIF1. For the 530 to 1700 kHz AM band with a 10.7 MHz first IF, the VCO goes from 11.23 to 12.40 MHz. Therefore, Fmax/Fmin for VCO is only 1.104, so one low–cost tuning diode can be used. Since the required tuning voltage range can be made less than 5.0 V, it may also be possible to drive the tuning diode directly or from the phase detector of the synthesizer IC, such as the Motorola MC145170, operating from 5.0 V, without using a buffer amplifier or transistor. If the VCO is above the incoming frequency, the image frequency of the first mixer is at fOSC + FIF1. For the AM broadcast receiver, it is around 22 MHz, so a simple LPF can be used between the RF stage and Mixer1 input. However, if a LPF is used, an additional coil is still needed to supply the collector voltage of the RF amplifier. For this reason, a BPF filter was used in the application circuit instead, since it uses the same number of coils and gives better performance. It is simply a lowpass to bandpass conversion. The lowpass filter is designed to have a cutoff frequency equal to the desired bandwidth. In this case, it would be 1700 – 530 kHz = 1170 kHz. Then, it is transformed to be resonant at 949 kHz, the geometric mean of the end frequencies: 1700 x 530 = 949 kHz. p A balanced–to–unbalanced transformer is required at the output of both mixers. The first one is designed so that Mixer1 has enough gain to overcome the loss of the 10.7 MHz filter and so that the output of the mixer will not overload before the input. The primary impedance of the transformer is relatively low, and it may be difficult to control with commonly available 7.0 mm transformers because the number of primary turns is quite small. It would also require a large tuning capacitance. A better solution is to tune the secondary with a small capacitance and then use a capacitive divider to match the tuned circuit to the filter. This allows one transformer to be used for either a ceramic or crystal filter. The capacitors can be adjusted to match the filter. The recommended coil is made this way. If the formula: Pin = IP3 – DR/2 is used, the maximum input level to the mixer can be calculated for a desired dynamic range. IP3 = 3rd order intercept level in dB (dBm or dB µ) DR = dynamic range in dB between the desired signals and 3rd order intermodulation products Pin = input level in dBm or dBµ The RF AGC level can then be adjusted so that Pin does not exceed this level. Whether or not a narrow bandwidth crystal or wide bandwidth ceramic filter is used between the first and second mixers depends on the receiver requirements. It is possible to achieve about 50 dB adjacent channel and IM rejection with a ceramic filter because of the wide dynamic range of the mixers. If more than this is required, a crystal filter should be used. If a crystal filter is used, a lower cost CFU type of 455 kHz second IF filter can be used. If a ceramic filter is used, a CFW type filter should be used because there is no RF section selectivity in this type of radio. Since the wideband AGC system is quite sensitive, it can be set to eliminate all spurious responses present at the receiver output. However, the RF AGC will sometimes eliminate or reduce the level of desired signals if there is a strong signal somewhere in the bandpass of the RF circuit. The second mixer is designed like the first and requires a balanced output. Since its load impedance is higher, the transformer can be designed to be tuned on the primary or |
Número de pieza similar - MC13030DW |
|
Descripción similar - MC13030DW |
|
|
Enlace URL |
Política de Privacidad |
ALLDATASHEET.ES |
¿ALLDATASHEET es útil para Ud.? [ DONATE ] |
Todo acerca de Alldatasheet | Publicidad | Contáctenos | Política de Privacidad | Intercambio de Enlaces | Lista de Fabricantes 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 |