Jeffrey Harrison

A 500 MHz CMOS anti-alias filter using feed-forward op-amps with local common-mode feedback

A 500 MHz op-amp-RC filter in a 0.18 /spl mu/m CMOS process achieves an integrator signal swing of 1.73 V/sub pp/ for -40 dB THD and thermal noise of 18 nV//spl radic/Hz. A three-stage op-amp with two feed-forward paths and common-mode feedback local to each stage is used. The op-amp features 8 GHz unity-gain frequency and 40 dB gain at 500 MHz.

60GHz Radios: Enabling Next-Generation Wireless Applications

Up to 7 GHz of continuous bandwidth centred around 60 GHz has been allocated worldwide for license free wireless communications. Highly attenuated due to oxygen absorption and small in wavelength, this band is ideal for extremely high data rate wireless data applications. These include numerous WPAN/WLAN applications such as home multimedia streaming. Traditional RF circuits used in this band are based on expensive compound semiconductor technologies. However for viable consumer applications, alternatives must be found. SiGe and CMOS based circuits are showing promise for enabling this technology at a price within reach of the consumer. This paper summarises a joint project aimed at developing high rate consumer level mm-wave wireless data systems. In particular, results to date in our RF design efforts are summarised.

Analytic limitations on sigma-delta modulator performance

Analytic limitations on the noise transfer function of sigma-delta modulators are derived. The noise transfer function magnitude in decibels integrated against frequency sums to at least zero. An excess delay of one sample in the modulator feedback loop is found to be detrimental for lowpass modulators.

Energy storage and Gramians of ladder filter realisations

An invariant of the controllability Gramian K and observability Gramian W, namely tr(KW), is expressed as an integral over frequency of the transfer function group delay weighted by power gain. This formula has strong connections with the old theory linking energy storage, sensitivity and group delay in LC networks. The Gramians of a doubly-terminated LC ladder filter realisation are discussed using this energy storage interpretation.

A frequency-domain approach to frequency-weighted balanced realization

The Ho-Kalman/Kung algorithm for balanced realization by singular-value decomposition of the Hankel operator has a natural frequency-domain equivalent. The controllability operator and observability operator are represented by intermediate transfer functions, called the gain to states and noise gain respectively. The product of these, the Hankel operator, can be expressed in terms of the input-output transfer function using an identity which the author refers to as the dynamic-range limitation. This frequency-domain theory extends naturally to the frequency-weighted case, and further to non-integrator-based linear fractional systems. It also provides additional design insight into the filter dynamic-range problem.

A 60 GHz diversity LNA in 0.18ìm SiGe

A combination low noise amplifier (LNA) and diversity switch (diversity LNA) is presented, allowing the switching between two spatially separated antennas to improve the received SNR in a multipath environment. This 60 GHz diversity LNA has a simulated gain of 14.3 dB and noise figure o f8.9 dB. It is suitable for diversity of reception implementation for a complete system-on-chip (SOC) in the 60 GHz band.

Formal synthesis of circuits using linear matrix inequalities

An algorithm is presented for synthesizing a linear time-invariant n-port with given impedance matrix at a set of frequencies, from ideal transformers and multiple instances of a given set of devices. The key step is to solve a linear matrix inequality which is based on the Pick matrix of Nevanlinna-Pick interpolation, extended to include reciprocity and multiple arbitrary types of device.

A high-frequency divider in 0.18 µm SiGe BiCMOS technology

High speed frequency dividers are critical parts of frequency synthesisers in wireless systems. These dividers allow the output frequency from a voltage controlled oscillator to be compared with a much lower external reference frequency that is commonly used in these synthesisers. Common trade-offs in high frequency dividers are speed of division, power consumption, real estate area, and output signal dynamic range. In this paper we demonstrate the design of a high frequency, low power divider in 0.18 µm SiGe BiCMOS technology. Three dividers are presented, which are a regenerative divider, a master-slave divider, and a combination of regenerative and master-slave dividers to perform a divide-by-8 chain. The dividers are used as part of a 60 GHz frequency synthesizer. The simulation results are in agreement with measured performance of the regenerative divider. At 48 GHz the divider consumes 18 mW from a 1.8 V supply voltage. The master-slave divider operates up to 36 GHz from a very low supply voltage, 1.8 V. The divide-by-8 operates successfully from 40 GHz to 50 GHz.

A limitation on active filter dynamic range

A resolvent identity is used to derive a fundamental relationship between the dynamic range of an active filter, its transfer function, and the dynamic range of its integrators. This dynamic range limitation leads to a frequency-domain representation of the Hankel operator in terms of the transfer function only.

Deep submicron CMOS: Characteristics & circuit design

The article presents 0.13 /spl mu/m device properties for CMOS integrated circuits, including transistors and passives. Circuit design principles and characteristics of RF circuits are covered. Circuit techniques for gain stages are also discussed. The article concludes with some technology predictions.