Voltage-controlled oscillator

About: Voltage-controlled oscillator is a research topic. Over the lifetime, 23896 publications have been published within this topic receiving 231875 citations. The topic is also known as: VCO.

Temperature compensated frequency generating circuit

Abstract: The frequency of an integrated oscillator is held constant by using temperature compensation to compensate for the component variations due to temperature variations. A voltage controlled oscillator, which has temperature dependent components, is compensated with a temperature dependent control voltage. The frequency of many kinds of oscillators such as a relaxation oscillators and ring oscillators can be held constant when the operating current is held constant. The operating current is often derived from a current source, which is a voltage to current converter with a current equal to the ratio of a control voltage to a resistance. Since semiconductor resistance has a positive temperature coefficient is used to obtain a temperature invariant current source. The positive temperature coefficient is obtained with the difference junction voltage of two forward-biased pn junction voltages. The magnitude can be controlled by junction areas of the two junctions. The magnitude can also be amplified.

An RF-powered, wireless CMOS temperature sensor

Abstract: We present a wireless, fully integrated CMOS temperature sensor that recovers power from a radio frequency (RF) signal, and returns data as a frequency-modulated 2.3-GHz signal to a base station. Power is recovered from a 450-MHz incident signal with the help of a low-threshold, high-efficiency, voltage rectifier-multiplier circuit. This technique decreases the minimum incident RF power required, compared to state-of-the-art wirelessly powered telemetry systems. The rectifier-multiplier can collect energy from a base station placed up to 18 m away. To further increase the range from the base, the device collects energy in a low power standby/charging mode. A mode selector circuit monitors the amount stored energy and decides if the system is transmitting data or is in the standby/charging mode. A bootstrapped reference generates a complementary to absolute temperature (CTAT) voltage with an R-squared regression of 0.9995 to a linear fit. This reference is used as the temperature sensor of the system, controlling a low-power, integrated, voltage-controlled LC oscillator (VCO). The oscillation frequency of the VCO is modulated by ambient temperature changes. The modulated carrier is transmitted by a fully integrated power amplifier. A temperature sensitivity of 126 ppm/degC is achieved and the entire sensor consumes 1.1 mA while transmitting data

High-speed voltage-controlled oscillator with quadrature outputs

Abstract: A voltage-controlled oscillator topology is described that combines a fully-differential four-stage ring oscillator with a balanced exclusive NOR gate frequency doubler, and provides both inphase and quadrature output signals at twice the ring oscillator frequency. These quadrature signals have a period of only four gate delays, which implies high frequency operation.

A 0.6-2.5 GBaud CMOS tracked 3/spl times/ oversampling transceiver with dead-zone phase detection for robust clock/data recovery

Abstract: For generation of the multiphase clocks for a serializer, a wide-range multiphase delay-locked loop (DLL) is used in the transmitter to avoid the detrimental characteristics of a phase-locked loop (PLL), such as jitter peaking and accumulated phase error. A tracked 3 /spl times/ oversampling technique with dead-zone phase detection is incorporated in the receiver for robust clock/data recovery in the presence of excessive jitter and intersymbol interference (ISI). Due to the dead-zone phase detection, phase adjustment is performed only on the tail portions of the transition histogram in the received data eye, thereby exhibiting wide pumping-current range, large jitter tolerance, and small phase error. A voltage-controlled oscillator (VCO), based on a folded starved inverter, shows about 50% less jitter than one with replica bias. The transceiver, implemented in 0.25-/spl mu/m CMOS technology, operates at 2.5 GBaud over a 10-m 150-/spl Omega/ STP cable and at 1.25 GBaud over a 25-m cable with a bit error rate (BER) of less than 10/sup -13/.

An Integrated 0.6–4.6 GHz, 5–7 GHz, 10–14 GHz, and 20–28 GHz Frequency Synthesizer for Software-Defined Radio Applications

Abstract: We present an integrated frequency synthesizer which is able to provide in-phase/quadrature phase signal over the frequency bands 0.6-4.6 GHz, 5-7 GHz, 10-14 GHz, and in-phase signal over 20-28 GHz for software-defined radio applications. An integrated voltage-controlled oscillator (VCO) with 34% tuning range and a set of high-speed dividers are used to accomplish all the frequencies. To achieve a wide tuning range while keeping a low gain and a low phase noise, the VCO employs digitally controlled sub-bands. The measured PLL phase noise is - 108 dBc/Hz, -121 dBc/Hz, and -135 dBc/Hz at 1 MHz offset for 24 GHz, 4 GHz, and 700 MHz, respectively. Fabricated in a 0.25 μm SiGe BiCMOS process, the synthesizer occupies a chip area of 4.8 mm2. The synthesizer was optimized for reconfigurable base station applications, but can also be used for cognitive radio, radar systems, satellite communication, and high-speed digital clock generation.