The painting canvas size of cell phone jammer

 The painting canvas size of cell phone jammer can be specifically made to meet the customer’s requirement.
Figure 4-7 Motorola P7689 phone GSM900 low-noise amplifier circuit. In the circuit, low-noise amplifier transistor Q400 is the core of the device. Q400 and the surrounding components together constitute the GSM900 low-noise amplifier. Which is the input capacitance C402, C405 is the collector output capacitance. LA02, R401, C403 and so together constitute a reactance filter power supply circuit, the RX-275-GSM power filtering, power supply and then to the collector of Q400; I_A01, R403, C403, also constitutes a reactance filter circuit, the RX- 275-GSM power supply filtering to Q400's base power. R401 is the exchange of load resistance, Q400 amplification is demonstrated by the resistance to adopt. L402 is the DC collector channels. In the base circuit, resistor R403 form a fixed bias circuit. Q400 in the core of low-noise amplifier circuit and the first one after one, there is a RF filter. The two RF filters are band-pass filter, allowing only the RF band GSM reception signal.
Improve the selectivity: the receiver frequency selectivity is generally close to the IF amplifier passband by the width of the decision. For the IF amplifier, not only need high gain, good selectivity, but also have enough good pass-band and frequency response, large dynamic range.In order to avoid mirror-frequency interference, improve the image frequency selective, receiver usually the first local oscillation frequency is reduced to improve the first IF frequency and multiple frequency method, the signal from the radio frequency spectrum and gradually move to a lower frequency. Phone circuits are mostly used in all on their own dedicated chip. IF amplifier circuit component separation of form and the form of low-noise amplifier circuit is very similar, but also a common emitter circuit, but their work is not the same frequency. The working instruction also contains the repair and maintenance of cell phone jammer .
Most mobile phones in the current circuit, Motorola mobile phones are usually used in the IF amplifier IF amplifier discrete components, and other mobile phones in the IF amplifier is usually an integrated circuit. As Figure 4-11 Motorola P7689 phone IF amplifier circuit. IF amplifier circuit in the form and the form of low-noise amplifier circuit is almost the same, but they cover different frequency work. Low-noise amplifier is a broadband amplifier, and the IF amplifier is a narrow band amplifier. In the case shown, the signal after the mixer through C460 anyone to FL457, FL457 selected by the 400MHz IF signal, IF signal amplified by Q480 to IF ICU200 demodulation, Q480 bias voltage of C7 by the U200 sent by SW-VCC pin provides.Reference frequency signal transmitting the signal from the transmit VCO signal with an oscillator RXVCO mixing.