QUADRATURE VCO THESIS

The target center frequency is 13 GHz; however it must initially be designed with a higher center frequency to account for frequency drop after post-layout simulation due to parasitic capacitance. As indicated, at 1 MHz offset, the phase noise is — Closed-loop PLL simulations for two loop bandwidths, 1 MHz and kHz, using a simple charge pump, PFD, loop filter, and Verilog-A divider confirm that settling time is inversely proportional to bandwidth. Examples of the relaxation oscillator include the multivibrator and the rotary travelling wave oscillator, but the most common one is the ring oscillator. The value of the input variable controls the flow of current through the two branches [37]. The design of PLLs for communication applications has been greatly impacted by the growing demand for multi-standard and multi-band communication systems.

Phase noise is inversely proportional to VCO output power and amplitude. Corner analysis is performed to observe the sensitivity of the two designs to process variations. A review of the measured performance of the two designs is shown in Table 7. A phasor based analysis is used for determining the amplitude and phase noise of these oscillators with MOSFET operation in cut-off, linear and saturation regions. VGS curve the value of Kn can be approximated by the squared current- voltage relationship for a MOS transistor in the active region:

This thesis tackles these challenges by presenting a detailed study of LC oscillators, monolithic elements for good-quality LC resonators, and circuits for IQ-signal generation and for frequency conversion, as well as many experimental circuits. When using a bias-T as part of the equipment setup, the phase noise improved by approximately 2 dB.

At this state the output current is zero and the output is a high-impedance node.

Low power low phase noise CMOS LC quadrature voltage-controlled oscillators

A phasor based analysis is used for determining quadgature amplitude and phase noise of these oscillators with MOSFET operation in cut-off, linear and saturation regions.

There is a buffer included in the reset path to act as a delay.

They thedis also used for matching with the voltage drop across the switches, resulting in the current reference being accurately mirrored to M5 and M7 [47].

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The parasitic parameters of the LC-tank limit the upper frequency band by restricting the upper tuning range [7].

Quadrature vco thesis

Therefore, it is possible to increase the operation frequency of the designed VCO or PLL using a more advanced technology. The measured temperature is used quaxrature a feedback loop to adjust the thermal tuner of the ring.

This feature of PLLs proves useful in many applications such bco radio, computers, telecommunications and other electronic applications [1]. At 8GHz the system consumes 2.

quadrature vco thesis

If the reset delay quzdrature the PFD is too vdo more noise will be introduced. Design A has two VCO cores and incorporates a source follower buffer, whereas Design B uses a switched-capacitor to increase tuning range. The above mentioned techniques along with some extra computations have been implemented to verify whether the proposed circuits can overcome the relaxation oscillations and can produce the proper sinusoidal waveforms or there is a need to devise some modifications.

quadrature vco thesis

It is important for PLLs to have dead zone elimination circuitry to ensure that the charge pump always comes on for some amount of time to avoid operating in the dead zone [49]. In general, the capacitance of the varactors is made small compared to the capacitance of the capacitors so the varactors have a larger effect on the total capacitance, which consists of two capacitors and two varactors in series, allowing for a larger frequency range.

The main reason for this popularity is probably the versatility of PLLs [3]. The inclusion of charge- pump buffers is for increased drivability to the charge pump. Electrical and Computer Engineering.

This can be estimated by two different methods. Nine circuit implementations with various actively synthesized variable capacitors were done. This measured performance is comparable with state-of-the-art wide-tuning-range VCOs. The W and L of transistors M1 and M2 were chosen to be as small as possible to reduce the input capacitance and therefore reduce the source follower load, since the input capacitance CGS is proportional to W and L [23] as shown as follows: Higher order PLL transfer functions are based on this, however are much more complex.

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This is because settling time is inversely proportional to bandwidth. The switches must be implemented as MOS transistors, which have series resistance when on, as well as parasitic capacitance to the substrate from their drain and source regions. A typical wide-tuning-range LC-VCO employs the use of a switched capacitor network for coarse tuning and a varactor for fine tuning, such as in [17,18]. In general, the tail current aids the designer in achieving a compromise between phase noise performance and power dissipation.

Therefore, the phase noise of the VCO is mainly determined by the overall quality factor Q of the circuit [27]. The aspect ratio of M1 and M2 was designed to guarantee that the VCO would work well, at the desired frequency. In some cases such as in [11], it has been reported that it may be advantageous to eliminate the tail current source to achieve better phase noise performance.

quadrature vco thesis

The circuit component values chosen for the loop filter must be a very carefully balanced compromise between a number of conflicting requirements. However, with a real oscillator, noise generates fluctuation on the phase and amplitude of the signal, so the output becomes: However, it is important to note that in general, an array of switched-capacitors can be used to achieve a larger tuning vck.

Because the phase frequency detector is made with real-world components, these gates have delays associated with them.

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