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BALANCED MODULATOR. In electronic communications, a balanced modulator is a circuit that produces double-sideband suppressed-carrier (DSBSC) signals: It suppresses the radio frequency carrier thus leaving the sum and difference frequencies at the output. The output waveform lacks the carrier, but still contains all the information a traditional AM signal has. This results in power saving during signal transmission . Types of balanced modulators include Lattice,1496/1596IC, and analog multiplier..

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BALANCED MODULATOR. A popular and widely used balanced modulator is the diode ring or lattice modulator. The lattice modulator consist of an input transformer, an output transformer and four diodes connected in a bridge circuit . The carrier signal is applied to the center taps of the input and output transformers. The modulating signal is applied to the input transformer. The output appears across the output transformer..

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BALANCED MODULATOR. Lattice Modulators The carrier sine wave is considerably higher in frequency and amplitude than the modulating signal. The carrier sine wave is used as a source of forward and reverse bias for the diodes. The carrier turns the diodes off and on at a high rate of speed. The diodes act like switches that connect the modulating signal at the secondary of T1 to the primary Of T2.

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BALANCED MODULATOR. IC BALANCED MODULATORS The 1496/1596 IC is a versatile circuit available for communication applications. It can work at carrier frequencies up to 100Mhz It can achieve a carrier suppresion of 50 to 65 DB The 1496/1596 IC can operate as a balanced modulator or configured to perform as an amplitude modulator a product detector or a synchronous detector..

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BALANCED MODULATOR. IC Balanced Modulators: Analog Multiplier An analog multiplier is a type of integrated circuit that can be used as a balanced modulator Analog multiplier are often used to generate DSB signals. The analog multiplier is not a switching circuit like the balanced modulator The analog multiplier uses differential amplifiers operating in the linear mode. The carrier must be a sine wave and the multiplier produces the true product of two analog inputs..

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BALANCED MODULATOR. This is another switching modulator During the positive half-cycles of the carrier, diodes D1 and D3 conduct and D2 and D4 are open. Terminal a is therefore connected to c and terminal b to d. During negative half cycle of the carrier D1 and D3 are open D2and D4 are conducting Terminal a and d are connected and so is b and c Output is proportional to m(t) during positive half-cycle and to –m(t) during the negative half-cycle..

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RING MODULATOR. M(T) is multiplied by a square pulse Wo (t) shown below. The fourier series of Wo (t) is given below: The signal m(t) Wo (t) is shown below: When m(t) Wo (t) is passed through a bandpass filter turned to Wc the filter output will be(4/Pi)m(t) cosWc (t).

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RING MODULATOR. The ring modulator circuit has two:m (t) and cosWct The input to the bandpass filter does not contain either of these input As a result this circuit is an example of a double balanced modulator..