The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 22, 1982
Filed:
Jun. 30, 1977
Charles R Hewes, Dallas, TX (US);
Texas Instruments Incorporated, Dallas, TX (US);
Abstract
A Modem utilizing process technology compatible CCD and IGFET circuits and sub-systems incorporated on a single I.C. chip. CCD transversal filters are employed as bandpass filters, being tuned for different modes of operation by adjustment of the clock frequency. The bandpass filters are operated in conjunction with a charge amplifier to remove d.c. offset from the analog output of the filters. The demodulator section of the Modem also incorporates low-pass filter employing switched resistors. The modulator section includes waveform generators based on a digital-to-analog converter including switched capacitors having values selected such that a sine wave having minimal distortion is generated when switched in proper sequence. Provision is made for digital inputs to control the frequency and amplitude of the sine wave output. The Modem can be operated under control of a microprocessor.