In the circuit shown, assume that diodes D₁ and D₂ are ideal. In the steady-state condition the average voltage V_ab (in Volts) across the 0.5 μF capacitor is _____.

In the circuit shown using am ideal opamp, the 3-dB cut-off frequency (in Hz) is _____.

In the circuit shown, assume that the opamp is ideal. If the gain ($${V_0}/{V_{in}}$$) is -12, the value of R (in K$$\Omega $$) is _____.

The modulation scheme commonly used for transmission from GSM mobile terminals is