Exam 6: RF Devices and Circuits

Colpitts oscillator operating at 50 MHz has an inductor in the feedback section of value 0.10µH. then the values of the capacitors in the feedback section is:

High gain is not achievable at microwave frequencies using BJT amplifiers because:

An inductor is operating at frequency of 50 MHz. Its inductance is 0.1 µH, and then the series resistance associated with the inductor is: (Qo=100)

__________  is defined as the ratio of input signal to noise ratio to the output signal to noise ratio.

Distributed amplifiers offer very high

The equivalent noise temperature of a network given the noise figure of the network or system is:

The necessary condition for oscillation in a Colpitts oscillator is:

_________uses balanced input and output, meaning that there are 2 signal lines, with opposite polarity at each port.

__________is a non linear circuit that converts DC power to an AC waveform of desired frequency based on the oscillator design.

In distributed amplifiers, all the FET stages in the amplifier are connected in series to one another.

__________is defined as the ratio of desired signal power to undesired noise power.

Coupler that is mostly used in balanced amplifiers to achieve the required performance is:

The transfer function of an RF oscillator is given by:

Bandwidth of balanced amplifier can be an octave or more, but is limited by the bandwidth of the coupler.

Hartley oscillator has inductance values of 12 mH and 4 mH in the feedback section and a capacitor of 4 nF. Then the resonant frequency of the circuit is:

To flatten the gain response of a transistor:

Along with a differential amplifier, 1800 hybrid is used both at the input and output.

A modern device that replaces a slotted line is:

If SWR=1.5 with a wavelength of 4 cm and the distance between load and first minima is 1.48cm, then the reflection coefficient is:

Amplifier efficiency is the ratio of RF output power to DC input power. This parameter determines the performance of an amplifier.