Subject: Mobile Communication

Difficulty: Medium

Marks: 4 marks

• The above block diagram is – Frequency Synthesizer A- Low Pass Filter(LPF) B- Voltage controlled Oscillator(VCO) C- Frequency Divider D- Prescaler

• Function of Identified Block-:Low Pass Filter(LPF)-A low-pass filter is a filter that passes signals with a frequency lower than a certain cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency

• Voltage controlled Oscillator(VCO)-:The output of VCO-2 is used as a local oscillator frequency for the first mixer in the receiver.The outputs of the two VCOs are mixed together to produce the transmitter output frequency.

• Frequency Divider-: Frequency dividers are used to generate a frequency that is a multiple of a reference frequency. These frequencies are then used for transmitters and receiver section The frequency divider block receives the divide by numbers from the logic section.

• Prescaler-: A prescaler is an electronic counting circuit used to reduce a high frequency electrical signal to a lower frequency by integer division.The purpose of the prescaler is to allow the timer to be clocked at the rate a user desires.