simulation of a superheterodyne receiver using pspice - School of ...

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Bandwidth = BW = ( f + f ) − ( f − f ) = 2 f c m c m m Experimental procedure: Simulation of an AM signal in Pspice requires three sinusoidal wave generators, with parameters shown below. These are then applied to a summing operational amplifier. The parameters are set up so as to achieve an AM wave with 50% modulation and a 1MHz carrier signal modulated by a 5kHz modulating signal, see Fig. 2 below. Therefore the bandwidth will be 10kHz. The amplitude of V1 is set to 1V (Em) and the value for V2 and V3 is given by: m = Em − Ec Em + Ec = 0.5 0.5(Em+Ec)=Em-Ec 1.5Ec=0.5 Ec=0.33 The phase is set to 90 as to achieve a cosine waveform as stated in the expression for the instantaneous amplitude of the carrier signal. Fig. 2: Generator Parameters. 8
Fig. 3: Amplitude Modulator. Setting up a Transient Analysis on the circuit with a print step of 20ns and a final time of 500us the AM signal generated is shown in Fig. 4 below. Note: A further generator (i.e. the image frequency) at a frequency of 1.91MHz will be added in the hierarchy structure to test for the image rejection in the RF stage. However for the purpose of simulating the AM signal it is left out now. Ref. [3] Appendix B Fig. 4: The AM signal. The frequency domain is more useful than the time domain when real AM signals are investigated (Fig. 5). The Fourier transform shows the spectral components are located at 995kHz, 1MHz and 1005kHz (i.e. the lower side band, the carrier and the upper side band respectively). 9
Page 1 and 2: SIMULATION OF A SUPERHETERODYNE REC
Page 3 and 4: CHAPTER 1: PROJECT ORGANISATION. Th
Page 5 and 6: modulating signal (Sensitivity). A
Page 7: amplitude of the carrier wave varie
Page 11 and 12: This is a quite high value, which m
Page 13 and 14: R Total IN IN 5 = R1 R2 R = 80k 50k
Page 15 and 16: was assumed that the drain-source r
Page 17 and 18: A V = g m R L = 5.56X10 −3 X1X10
Page 19 and 20: 1 Substituting for ω 2 = . LC T β
Page 21 and 22: −3 3 VD = VDD − I DRD = 20V −
Page 23 and 24: Ref. [6] Appendix B Fig. 21: Mixer
Page 25 and 26: Values for the second LC tuned circ
Page 27 and 28: Fig. 24: Double tuned IF amplifier.
Page 29 and 30: Fig. 28: Enlarged section of diode
Page 31 and 32: Fig. 30: AGC and audio signals. The
Page 33 and 34: I C 22.02mA BJT Q12 (pnp transistor
Page 35 and 36: The middle section of the hierarchy
Page 37 and 38: Fig. 40: Block 4 - Local oscillator
Page 39 and 40: Fig. 44: Block 8 - Audio amplifier.
Page 41 and 42: The first major test for the superh
Page 43 and 44: spectrum. However, as long as the I
Page 45 and 46: Fig. 50: Modulating frequency in AM
Page 47 and 48: * Working on the IF stages of the d
Page 49 and 50: are very important) combated this p
Page 51: Fig. 18: Local Oscillator (Amplifie

simulation of a superheterodyne receiver using pspice - School of ...

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