Positron Emission Tomography (PET) Medical Imaging Chip
This fully custom, mixed-signal, 0.5-μm CMOS chip processes front-end energy and timing from multi-element scintillation detectors used in positron emission tomography (PET) medical imaging. PET imaging provides highly sensitive, functional images of biochemical processes for diagnosing cancer, brain, and heart disease. The chip is used in Siemens PET medical tomographs, designed and manufactured by CTI PET Systems, a subsidiary of CTI Molecular Imaging (NASDAQ: CTMI).

The chip contains four, constant-bandwidth, 100-MHz, variable-gain preamplifiers with current-mode output summer circuits to provide detector energy and timing pulse decoding. A constant-fraction discriminator (U.S. patent 5,396,187) derives event time independent of signal amplitude and contains a 100 MHz continuous time filter, low time dispersion comparators, and thresholding logic utilizing low-metastability flip flops. This circuit contains novel (U.S. patent 6,822,506) wideband, continuous-time, negative feedback circuits to provide autozeroing and signal pulse tail cancellation for operation at random event rates up to 10 Mcps. Event time is digitized in a time-to-digital converter that utilizes time interpolation through a 5-b flash A/D converter for a timing resolution of 100 ps from a 100 MHz system timing clock. Anti-aliasing lowpass filters with digital offset control precede external 100-MHz pipelined A/D converters for subsequent energy and position digital processing. Eight bit D/A converters provide threshold and time alignment control through an addressable read/write serial interface. A test-input circuit permits both production and in-system testing. The chip is described in B. K. Swann et al., “A Custom Mixed Signal CMOS Integrated Circuit for High Performance PET Tomograph Front-End Applications,” Conference Record of the IEEE 2002 Nuclear Science Symposium and Medical Imaging Conference; D. M. Binkley et al., “A 10-Mcps, 0.5-μm CMOS Constant-Fraction Discriminator Having Built-In Pulse Tail Cancellation,” IEEE Transactions on Nuclear Science, June 2002; and B. K. Swann et al., “A 100-ps Time-Resolution CMOS Time-to-Digital Converter for Positron Emission Tomography Imaging Applications,” IEEE J. of Solid-State Circuits, November 2004.

Concorde Microsystems, Inc., Knoxville, TN

www.cms-asic.com

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Positron Emission Tomography (PET) Medical Imaging Chip (older version)
This fully custom, mixed-signal, 2-μm CMOS chip processes front-end energy, position, and timing from an 8 x 8 or 12 x 12 element scintillation detector used in positron emission tomography (PET) medical imaging. PET imaging provides highly sensitive, functional images of biochemical processes for diagnosing cancer, brain, and heart disease. The chip is used in Siemens PET medical tomographs, designed and manufactured by CTI PET Systems, a subsidiary of CTI Molecular Imaging (NASDAQ: CTMI). Both a BGO detector version of the chip and a newer, higher-speed LSO version have reduced front-end electronics cost, size, complexity, and power consumption by nearly a factor of five. In 2002, this chip was replaced by a new 0.5-μm version.

The chip contains four, 50-Ω, constant-bandwidth, 60-MHz, variable-gain preamplifiers with current-mode summer circuits to provide detector energy, position, and timing pulse decoding having less than 1 ns delay shift over a 10:1 gain range. A patented constant-fraction discriminator (U.S. patent 5,396,187) derives event time independent of signal amplitude and contains a 100-MHz continuous time filter, low time dispersion comparators having less than 0.5 ns delay variation for a 100:1 dynamic range, current-mode autozero circuits, and thresholding logic with ECL output drivers. Three autozeroed, gated integrators provide event energy, x, and y position with additive offsets for system alignment. Nine channels of 7- and 8-bit D/A converters provide gain, threshold, and offset control through an addressable read/write serial interface. A four-channel, current-mode, test-input circuit permits both production and in-system testing. The chip is described in D. M. Binkley et al., "A Custom CMOS Integrated Circuit for PET Tomograph Front-End Applications," Conference Record of the IEEE 1993 Nuclear Science Symposium and Medical Imaging Conference.

Concorde Microsystems, Inc., Knoxville, TN

www.cms-asic.com

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Micropower, Pet Containment Receiver Chip
This fully custom, mixed-signal, micropower, 2-μm CMOS chip is used in miniature, long battery life, receiver collars for buried-wire pet containment systems. These systems sense when a pet approaches the boundary defined by a modulated magnetic field from a buried wire. The chip reduced receiver collar power consumption from 3.5 mA to 30 μA, greatly extending battery life while reducing size and cost. Over two-million of these chips have been shipped in pet containment systems sold under the PET Safe (Radio Systems Corporation) name.

The chip provides front-end amplification, continuous-time highpass and lowpass filtering, envelope signal demodulation with threshold comparison, and digital algorithm control for controlling the pet collar. The chip utilizes power aware techniques, operating at only 30 μA for signals below a preset threshold. Above this threshold, an additional switched-capacitor, elliptic lowpass filter is enabled to provide notch rejection of 15.734-kHz television horizontal interference. When activated, the switched-capacitor filter and its related phase- locked-loop (PLL) clock multiplier raise the total chip current consumption to 60 μA. The chip contains a 32.768-kHz tuning fork oscillator to clock the digital algorithm state machine and provide the PLL reference frequency. Additionally, the chip contains a bandgap reference for regulating device bias currents and signal thresholds.

Concorde Microsystems, Inc., Knoxville, TN

www.cms-asic.com

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Pet Containment Transmitter Chip
This fully custom, mixed-signal, 2-μm CMOS chip is used for transmitter signal synthesis in buried-wire pet containment systems sold under the PET Safe (Radio Systems Corporation) name. These systems sense when a pet approaches the boundary defined by a modulated magnetic field from a buried wire.

The chip synthesizes a differential, 20-step, envelope-modulated, sine-wave signal followed by a lowpass reconstruction filter. Current-mode, differential to single-ended conversion circuitry provides two, single-ended outputs, each rail-to-rail output having a total harmonic distortion of only 0.2%. A digital algorithm circuit controls amplitude modulation of the synthesized signals, while automatic signal leveling and wire break detection are provided from active rectification of the sampled buried- wire current. A 32.768-kHz tuning fork oscillator and phase-locked-loop (PLL) synthesizer provide clocks for the digital algorithm and over-sampled sine-wave synthesis. A bandgap reference regulates signal levels and an on-chip shunt regulator that permits the chip to operate off unregulated power supplies.

Concorde Microsystems, Inc., Knoxville, TN

www.cms-asic.com

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Micropower, Direct Conversion Receiver Chip for Wireless Pet Containment System
This fully custom, mixed-signal, 2-μm CMOS chip is used in miniature, long battery life, receiver collars for wireless pet containment systems sold under the PET Safe (Radio Systems Corporation) name. These systems (U.S. patent pending) sense when a pet moves beyond a programmable radius up to 90 feet from a wireless, magnetic field transmitter.

The single-chip, micropower, very low frequency (VLF), direct-conversion receiver contains an RF preamplifier, RF automatic gain control (AGC), a direct-conversion mixer, and dual I/Q baseband, lowpass amplifiers. Delta- sigma quantizers provide 9-bit digital I/Q outputs at a 120-Hz conversion rate in conjunction with a companion digital signal processing chip. A phase-locked-loop (PLL) synthesized local oscillator, operating off a 32.768-kHz tuning-fork oscillator reference, provides receiver tuning over a 10 - 82-kHz range. The RF input noise floor is 0.3 μV in a 300-Hz bandwidth, local oscillator isolation exceeds 145 dB, and the AGC control range exceeds 44 dB. Lateral PNP bipolar transistors, inherent in the CMOS process, provide low flicker noise in the RF preamplifier and low dc offsets in the baseband amplifiers which utilize continuous-time autozero circuits. An internal bandgap reference provides bias references while an active low-impedance, mid-supply generator creates a 10-Ω impedance level using only 6 μA of supply current. Total chip current consumption is 80 μA. The chip is described in D. M. Binkley et al., "A Micropower CMOS, Direct-Conversion, VLF Receiver Chip for Magnetic-Field Wireless Applications," IEEE Journal of Solid-State Circuits, vol. 33, no. 3, March 1998, pp. 344-358.

Concorde Microsystems, Inc., Knoxville, TN

www.cms-asic.com

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Transmitter Chip for Wireless Pet Containment System
This fully custom, mixed-signal, 2-μm CMOS chip is used for transmitter signal synthesis in wireless pet containment systems sold under the PET Safe (Radio Systems Corporation) name. These systems (U.S. patent pending) sense when a pet moves beyond a programmable radius up to 90 feet from a wireless, magnetic field transmitter.

The chip synthesizes three phase-modulated, 16-step, sine-wave signals followed by lowpass reconstruction filters. Rail-to-rail outputs permit the chip to drive external power amplifiers associated with the magnetic field transmitter. A digital algorithm section controls phase modulation and phase shift between the three channels. An internal, phase-locked-loop (PLL) synthesizer generates the oversampled sine-wave synthesis clock from a reference, 32.678-kHz tuning fork crystal oscillator. A bandgap reference regulates signal levels and an on-chip shunt regulator that permits the chip to operate off unregulated power supplies.

Concorde Microsystems, Inc., Knoxville, TN

www.cms-asic.com