Frequency Translation

Frequency Translation: The frequency translation means shifting the frequency of an oscillator by a small factor. Fig. 2.134 shows the block schematic for frequency translator using PLL. It consists of mixer, low pass filter and the PLL. The input frequency fs which has to be shifted is applied to the mixer. Another input to the […]

Frequency Shift Keying Demodulator

Frequency Shift Keying Demodulator: In digital data communication, binary data is transmitted by means of a carrier frequency. It uses two different carrier frequencies for logic 1 and logic 0 states of binary data signal. This type of data transmission is called frequency shift keying (FSK). In- this data transmission, on the receiving end, two carrier […]

Frequency Synthesizer

Frequency Synthesizer: The PLL can be used as the basis for frequency synthesizer that can produce a precise series of frequencies that are derived from a stable crystal controlled oscillator. The Fig. 2.130 shows the block diagram of frequency synthesizer. It is similar to frequency multiplier circuit except that divided by M network is added […]

Frequency Multiplier

Frequency Multiplier: Fig. 2.128 shows the block diagram for a frequency multiplier using PLL 565. Here, a divide by N network is inserted between the VCO output (pin 4) and the phase comparator input (pin 5). Since the output of the divider is locked to the input frequency fi, the VCO is actually running at […]

Monolithic Phase Locked Loops IC 565

Monolithic Phase Locked Loops IC 565: Monolithic Phase Locked Loops IC 565 are introduced by signetics as SE/NE 560 series and by National semiconductor as LM 560 series. The SE/NE 560 series includes SE/NE 560, 561, 562, 564, 565 and 567. These ICs are differ mainly in operating frequency range, power supply requirements, and frequency […]

Important Definitions Related to PLL

Important Definitions Related to PLL: Some important definitions related to PLL are as follows : Lock Range: When PLL is in lock, it can track frequency changes in the incoming signal. The range of frequencies over which the PLL can maintain lock with the incoming signal is called the lock range or tracking range of […]

Foldback Current Limiting

Foldback Current Limiting: The disadvantage of constant current limit is relatively large power dissipation in the series pass transistor when the load terminals are shorted. Thus a large power rating transistor is required. The Foldback Current Limiting technique allows us to provide the necessary load current at rated voltage but reducing the short circuit current. […]

Constant Current Limiting Circuit

Constant Current Limiting Circuit: A block of series regulation using simple Constant Current Limiting Circuit is shown in the Fig. 2.119. It is also called short circuit protection circuit as it provides protection against short circuiting. The resistance R4 is added in series with the pass transistor Q1and the load which is called current sensing […]

Protection Circuits in Regulators

Protection Circuits in Regulators: Protection Circuits in Regulators- The series regulator using transistors has no short circuit protection. If the load terminals are shorted accidentally then, Large amount of load current will flow. The pass transistor Q1 will get destroyed. The diodes used in unregulated power supply, supplying the input voltage Vin to regulator circuit […]

Positive High Voltage High Current Regulator

Positive High Voltage High Current Regulator: Positive High Voltage High Current Regulator – For this type, output voltage from +7V to +37V and load current IL > 150 mA. For this a external transistor Q1 is connected, as shown in the Fig. 2.115. For this different expressions are similar to basic high voltage regulator and reproduced […]