Wing Kin Liu

US Patent:

6750357, Jun 15, 2004

Filed:

Jun 25, 1999

Appl. No.:

09/344226

Inventors:

Ronald H. Chiarello - Castro Valley CA
Wing Liu - Belmont CA
Kathy E. Yokobata - Sunnyvale CA

Assignee:

SynGen, Inc. - San Carlos CA

International Classification:

C07D31178

US Classification:

549394, 436172, 436800

Abstract:

Fluorescent dyes based on rhodamine are derivatized to form labeled conjugates that fluoresce upon excitation with light of an appropriate wavelength. Particularly preferred embodiments are certain single isomer form rhodamine phosphoramidites. These rhodamine phosphoramidites enhance the efficiency of synthesizing rhodamine-labeled oligonucleotides by solid phase methods. Conjugate embodiments of the invention are prevented from being converted to a non-fluorescent lactam form due to having a fully substituted amide linkage derived from the 3-position carboxylate.

US Patent:

7002423, Feb 21, 2006

Filed:

Jul 20, 2004

Appl. No.:

10/710549

Inventors:

Boris Drakhlis - Mountain View CA, US
Wing Faat Liu - San Jose CA, US
Craig M. Taylor - Pleasanton CA, US
Tony Yeung - Milpitas CA, US

Assignee:

Pericom Semiconductor Corp. - San Jose CA

International Classification:

H03B 5/32

US Classification:

331158, 331116 R, 331116 FE, 331 74, 331107 A

Abstract:

A crystal oscillator operates at the third overtone of the crystal's fundamental frequency. A value of a shunt resistor between the two phase-shift leg nodes is chosen so that the absolute value of the product gm×(Xc)×(Xc) is greater than the effective reactance of the crystal, where gm is the gain of the amplifier attached to the phase-shift legs, and Xc and Xc are the effective capacitive reactances of phase-shift legs at nodes X and X. The third overtone is doubled by a multiplier and the final output filtered to remove the third overtone and select a frequency six times the fundamental frequency. A pair of Colpitts or Pierce amplifier half circuits is attached to the phase-shift leg nodes. The leg nodes can be capacitively isolated from Pierce-amplifier circuit nodes to improve start-up. Frequency doubling can be performed by summing currents from the two oscillator half circuits.

US Patent:

7332977, Feb 19, 2008

Filed:

Dec 21, 2005

Appl. No.:

11/306262

Inventors:

Boris Drakhlis - Mountain View CA, US
Wing Faat Liu - San Jose CA, US
Craig M. Taylor - Pleasanton CA, US
Tony Yeung - Milpitas CA, US

Assignee:

Pericom Semiconductor Corp. - San Jose CA

International Classification:

H03B 27/00

US Classification:

331 46, 331 49, 331 53, 331158, 331116 R, 331116 FE, 331 74

Abstract:

A crystal oscillator operates at the third overtone of the crystal's fundamental frequency. A value of a shunt resistor between the two phase-shift leg nodes is chosen so that the absolute value of the product gm×(Xc)×(Xc) is greater than the effective reactance of the crystal, where gm is the gain of the amplifier attached to the phase-shift legs, and Xc and Xc are the effective capacitive reactances of phase-shift legs at nodes X and X. The third overtone is doubled by a multiplier and the final output filtered to remove the third overtone and select a frequency six times the fundamental frequency. A pair of Colpitts or Pierce amplifier half circuits is attached to the phase-shift leg nodes. The leg nodes can be capacitively isolated from Pierce-amplifier circuit nodes to improve start-up. Frequency doubling can be performed by summing currents from the two oscillator half circuits.