Chung Ming Yuen

A 1.8-V distributed voltage-controlled oscillator module for 5.8-GHz ISM band

This letter presents the design and implementation of a 1.8-V 5.8-GHz distributed voltage-controlled oscillator module based on bipolar transistors. The oscillator delivered -2-dBm-output power with a current consumption of 11.5 mA. The tuning range achieved was 650 MHz. The measured phase noise was -100 dBc/Hz at 1-MHz offset. The circuit construction was simple and robust and no buffer amplifier was needed. The design can be used for 5.8-GHz ISM band wireless LAN applications.

Phase noise measurement of free-running microwave oscillators at 5.8 GHz using 1/3-subharmonic injection locking

An innovative method using subharmonic injection locking technique for the phase noise measurement of free-running microwave oscillators is presented. To reduce the system cost, a two-tier injection locking approach is used and an effective 1/3-subharmonic injection is established. Measurement on a 1.8-V 5.85-GHz voltage controlled oscillator demonstrates that the measurement system is promising.

An automatic tracking system for phase-noise measurement

A low cost, automatic tracking system for phase noise measurement has been implemented successfully. The tracking system is accomplished by applying a charge pump phase-locked loop as an external reference source to a digital spectrum analyzer. Measurement of a 2.5 GHz, free-running, voltage-controlled oscillator demonstrated the tracking accuracy, thus verifying the feasibility of the system.

Low voltage circuit design techniques for voltage controlled oscillator

This paper discusses some high frequency circuit design techniques for low voltage operation and low power consumption voltage controlled oscillators. The target operating voltage is 2 V (power supplied by only two pieces of rechargeable NiCd battery). Various resonators and circuit configurations were studied for optimal performance. A major difficulty was found in achieving high spectral purity on such low supply voltage. The presented investigation introduces efficient ways to the design of low voltage VCO for sufficient output power, low phase noise and also wide tuning range. With the simplicity and high performance, the proposed design ideas would be attractive for applications to low voltage portable products.

A Low-Voltage Fast Switching Frequency Synthesizer for FH-SS Applications

This brief presents a novel 2.7-V frequency synthesizer for frequency hopping spread spectrum applications. To accomplish fast switching, the frequency synthesizer utilizes a memory access technique to retrieve the precalibrated and digitized tuning voltage values. The phase noise and the frequency accuracy of the frequency synthesizer are analyzed. The channel efficiency, the frequency switching performance, and the output spectral purity are investigated at 2.4 GHz. Measurement shows that the channel switching time is 5 mus. Thus, the proposed synthesizer is promising for frequency hopping wireless communication. The developed architecture is ready to be used for application-specified integrated circuit design

Phase noise measurement of free-running VCO using spectrum analyzer

This work presents a cost-effective solution to measure the phase noise of a free-running microwave voltage controlled oscillator using a spectrum analyzer with add-on phase noise measurement software utility. To solve the frequency drift problem, the reference source is externally provided and tracked to the signal being tested. The system accepts random frequency drift up to +/-100 ppm. Measurement of the phase noise of a 2.5 GHz free-running voltage controlled oscillator is demonstrated. The result shows the accuracy, effectiveness and repeatability of the proposed method.

A high channel efficiency transceiver based on direct access frequency synthesis technique

A novel high channel efficiency transceiver based on a fast acquisition frequency synthesizer has been designed. The direct access frequency synthesis technique is applied and a simple memory look-up table is incorporated to expedite channel acquisition. The technique simplifies the frequency control process in the transceiver and thus reduces the channel switching time. As a result, the channel efficiency is improved. The proposed transceiver is ideal for frequency hopping mobile communication applications.

1/spl mu/s fast acquisition 2.4 GHz low voltage frequency synthesizer for FH-CDMA mobile communications

This paper discussed the design of a fast acquisition frequency synthesizer for frequency hopping CDMA in the 2.4 GHz band. The frequency synthesizer can make channel switching within one microsecond while operating at 3 V. In order to achieve fast acquisition, low phase noise and low harmonic content under very low supply voltage, specially designed voltage controlled oscillator, frequency doubler and switchable loop filter were adopted for optimum performance. Measurements on the prototype showed that the acquisition time was 0.79 /spl mu/s. The proposed design is suitable for the low voltage and low power handheld equipment. With minor modification, the design can be applied to other digital cellular applications, such as DCS-1800 handsets.

Medium power oscillator design for 1.8 GHz band using large signal S-parameter analysis

The design and implementation of an 1.8 GHz voltage controlled oscillator are presented in this paper. The oscillator can provide 0.3 W output power at 6 V supply. With the simplicity in circuit construction, the component count can be largely reduced compared with the traditional multiple stage approach. For a convenient way to extract the design information from the completed circuit, the external feedback path of the oscillator is broken down so that the oscillator circuit was reformed to be a open-loop non-oscillating two-port network. The characteristic of the network can be analyzed easily. Significant predictions of the oscillators performances drawn from such analysis are described.