UGC-NET Electronic Science Question Paper With Answer Key Download Pdf [June 2025] Download Question Paper                   2025 | 2024 | 2023 | 2022 | 2021 | 2020 UGC-NET Electronic Science  June 2025 Answers with Explanations Explanations 1. For forming a p-type semiconductor, the dopant must be a trivalent impurity (three valence electrons) so that it creates acceptor levels and holes become the majority carriers. Among the given elements, boron (B) is a group-III element (trivalent). Arsenic (As) and phosphorus (P) are group-V (pentavalent) donors that produce n-type material, and germanium (Ge) is a group-IV element usually used as the semiconductor, not as an acceptor dopant. Hence, doping an intrinsic semiconductor with B produces a p-type semiconductor. 2. The ohmic resistance of a JFET at zero gate bias is given by the standard relation: R DS(on) = V P / I DSS because ...

Simulator for QPSK Modulation Quadrature (4-PSK) Bitstream (Even length) Carrier Freq (Hz) Samples Per Symbol Run QPSK Simulation The Math Behind QPSK Quadrature Phase Shift Keying (QPSK) is a form of digital modulation that transmits two bits per symbol by changing the phase of a carrier wave. s(t) = A cos(2πf c t + θ n ) Phase (θ n ): Each pair of bits (dibit) corresponds to a specific phase shift. In Gray coding, we use: "00" → π/4 (45°) "01" → 3π/4 (135°) "11" → 5π/4 (225°) "10" → 7π/4 (315°) Efficiency: Since 4 phases are used, QPSK carries double the data of BPSK in the same bandwidth. ...

  BFSK Orthogonality Simulator BFSK Orthogonality Simulator T: f₁: f₂: Run Simulation Signals 📘 Mathematical Model Behind the Simulator The simulator generates two sinusoidal signals used in Binary Frequency Shift Keying (BFSK): s₁(t) = cos(2πf₁t) s₂(t) = cos(2πf₂t) To check orthogonality, it computes the inner product: ∫₀ᵀ s₁(t)s₂(t) dt If the result is approximately zero, the signals are orthogonal. ⚙️ What Each Input Means T (Symbol Duration) This defines the time interval over which signals are observed. Orthogonality depends directly on this value. 0 ≤ t ≤ T f₁ (Frequency 1) Frequency of the first BFSK signal (represents binary "0" or "1"). cos(2πf₁t) f₂ (Frequency 2) ...

  Lumped vs Distributed Circuits Lumped Circuit vs Distributed Circuit The difference between lumped and distributed circuits comes down to how voltage, current, and physical size relate to the signal wavelength. Lumped Circuit Concept: Components are assumed to be concentrated at discrete points. Condition: \[ \text{Size of circuit} \ll \lambda \] Where \( \lambda \) is the wavelength of the signal. Assumptions: Voltage and current are uniform across components No propagation delay Governing Laws: Ohm's Law: \( V = IR \) Kirchhoff’s Laws (KVL and KCL) Examples: DC circuits Low-frequency AC circuits Basic electronic circuits Distributed Circuit Concept: Electrical parameters are distributed continuously along the conductor. Condition: \[ \text{Size of circuit} \approx \lambda \ \text{or larger} \] Characteristics: Voltage and current vary with ...

📘 Instructions ⚙️ Simulator 📡 Demodulate 📈 Graphs OFDM Simulation Tool Interactive Virtual Lab: Configure parameters and visualize BPSK mapping & IFFT transformations. Start Simulator Now Instructions for OFDM Modulation with BPSK Follow these steps to complete the modulation process: Note: Use the input fields to enter symbols, subcarriers, CP length, frequency, and Baud Rate. Step 1: Generate Message button for input bitstream. Step 2: 'Make OFDM Symbol' to map bits. Step 3: 'Generate Subcarr...